Exp. Clin. Endocrinol. Vol. 96, No. 1, 1990, PP. 83-89
J. A. Barth, Leipzig
Buda Children's Hospital (Head: Prof. Dr. F. Péter) and "Korányi" Institute of TBC and Pulmonology' (Head: Prof. Dr. O. Schweiger), Budapest/Hungary
Insulin Metabolism in Hypothalamic Obesity With 2 Figures
Summary. Serum C-peptide and Immunoreactive Insulin (TRI) level was measured during per os glucose tolerance test as well as fasting specific insulin binding percentage and capacity of erythro-
cytes in hypothalamic obesity and in obese children due to hypercalorization, and was compared with ideal-weight controls. Integral values of curves (27) and EC-peptide/271R1 ratios were calculated.
In 4 cases fasting C-peptide content was substantially increased as compared to the other groups. The data suggest that hyperinsulinism in diencephalic obesity is primary. The ratio of the two peptides was normal or increased; insulin binding % of erythrocytes corresponded to that of the control group, which explains in these cases normal or favourable glucose metabolism. It is thought that in obese
children high fasting C-peptide levels with an adequate clinical picture can indicate the functional examination of the hypothalamic-pituitary system. £C-peptideJL'TRI ratio differing from normal indirectly shows the changes of receptor function. Key words: Hypothalamic obesity - C-peptide - Immunoreactive insulin - Insulin receptor
Introduction It has been widely assumed that genetic factors and anabolic-oriented shift in energy balance have a basic role in the pathogenesis of obesity. Moreover, it is becoming clearer f hat obesity may result in the dysfunction of the hypothalamic-pituitary system (York and Bray, 1972; Dunaif et al., 1988; Wajchenberg et al., 1988). It has been known since the first experiments of Hetherington and Ranson (1940) that hyperbulia and hyperphagy caused by destruction of the hypothalamic ventromedial nuclei (VMN) results in excessive obesity (Anand and Brobeck, 1951; Goldman et al., 1972). In the background of hyperbulia neurohumoral (Moltz et al., 1975; LockartEwart et al., 1976; Martin et al., 1981) and/or neuronic (Bray et al., 1981) effects are suspected. According to the general opinion the excess appetite in hypothalamic obesity (HO) is due to hyperinsulinemia (Han and Frohman, 1970; Martin, 1984). High fasting insulin level appeared to prove this fact. In previous studies C-peptide (CP) and Immunoreactive Insulin (TRI) determination was repeatedly performed during per os glucose tolerance test (OGTT) as well as the specific insulin binding percentage (SIB%) of ery-
throcytes in children with obesity due to hypercalorization (0) and without or with biguanides treatment (Blatniczky et al., 1985). It has been found that serum IRI level per se reveals no information about the reasons of the tendency of its quantities. A difference in insulin metabolism might depend on a different functional status of insulin receptors in various tissues (Bonora et al., 1986). Our publication assessesthe formation of
B-cell functional efficiency detected by CP determination in children with HO, and examines whether hyperinsulinism has a primary effect in this syndrome.
Downloaded by: Collections and Technical Services Department. Copyrighted material.
L. BLATNICZKY, L. KAUTZKY1 and F. PÉTER
84
Exp. Clin. Endocrinol. 96 (1990) 1
Materials and Methods In the past years 5 obese children (1 boy, 4 girls) have been examined at our outpatient clinic, whose HO syndrome was proved by anamnesis, clinical symptoms and the examinations performed
(Table 1). The capacity of the hypothalamic-pituitary system was examined (HGH in ITT and L-Dopa test; TSH, Prolactin in TRH test; LH, FSH in GnRH test; ACTH, Cortisol in i.v. Methyrapone test). Visual field and EEG examinations were performed in every case, CT in three cases Children were investigated after overnight starvation. 1.75 g/kg (max. 150 g) of glucose was administered orally and capillary glucose (Galenopharm-glucose oxidase), serum CP (Mallinckrodt Diagnostica-RIA) and TRI (Izinta-RIA) levels (in case K. G.: CP: 0, 60 and 150 mm) were determined every 30 min for 180 min. ECPf2'IRI ratio was determined by calculating integral values of the curves (E). These results were compared with the data of 10 normal-weight children aged 9-14 years and to those of 11 children with O (Table 1). In four children with HO SIB% of erythrocytes was determined with the method of Gambhir et al. (1977) and the insulin binding capacity (IBC) in the highaffinity receptor group was calculated with Scatchard analysis (Scatchard, 1949). Data obtained thereby were compared with those of 8 normal-weight children aged 8-15 years as well as with those of 9 obese children of the same age. Table 1 Main data of patients with hypothalamic obesity
Initials
Sex
Height Length
Age
(year)
K. G.
4
(cm)
age (year)
Weight Weigth
Diagnosis
for length (kg)
(SD)
132
9
36
2.8
E. N.
12 0/12
164
> 18
144
11.7
A. P.
13
167
> 18
121
8.0
Gigantism Tu. suprasellaris Adiposogigantism Diabetes insipidus
Mental retardation 112
Adiposogigantism
Mental retardation Gy. S.
15 /12
I. Cs.
17 6/12
178
168
> 18
>18
142
7.8
115
7.3
5.7 1.9
Adiposogigantism
Mental retardation Hypothalamic-pituitary dysfunction Diabetes insipidus Mental retardation
Obese children due to hypercalorization (n = 11)
i
± SD
128/a
163
15
98
1/l2
6
2
13
Results All children with HO were extremely obese, except A.G. who, however, put on 6 kg
in 4 weeks after the removal of a mixed-cellular (GH and Prolactin) suprasellar hypothalamic tumor. None of our patients displayed hyperfunction of the ACTH-adrenal axis. Multiple dysfunction was detected in one case; hyperprolactinemia in three cases. EEG showed diffuse cerebral electric dysfunction, except I. Cs.; CT suggested the possibility of diencephalie damage in all the patients examined (Table 2).
Downloaded by: Collections and Technical Services Department. Copyrighted material.
(Table 2).
85
L. BLATNICZKY et al., Hypothalamic Obesity and Insulin Metabolism
Informative data on the function of the hypothalamic-pituitary system in our patients
Initials HGH capacity TSH capacity ACTH rhythm Prolactin capacity LII capacity FSH capacity
K. G.
E. N.
A. P.
N N
N N N
N N N
t
N N N uncertain
1'
N N positive positive dwindled
CT
EEG* Visual field
N N uncertain positive N
N = normal, tt = increased-decreased capacity,
Gy. S.
I. Cs.
N N N
N
N N
positive dwindled
positive
N N
N
= no examination performed, * = positive
EEG diagnosis in each case indicated discrete diffuse cerebral damage
Glucose. During OGTT impaired glucose tolerance (National Diabetes Data Group, 1979) was found only in one patient (E. N.) (Fig. 1). In two cases normal and inK.G. and Gy. S. definitely decreased glucose response was found. C - pept ide. Fasting CP quantities were definitely higher in all patients with HO than in the control group, and in four cases they were higher than in the O group (Fig. 1, Table 3). During OGTT significant CP release was detected in each patient with HO and in two cases these levels were higher than the maximum detect- except K.G. able value of the RIA-kit (9.0 nmol/l). ECP level was higher in all patients than in the control group.
Serum C-peptide
>1 B
1
Capillary-glucose (mmol/l)
Serum RI
(nmol/i)
(n mol/i)
1.75g/kg glucose
1.75g/kg glucose
-8
1 1.75 g/kg glucose
I -4
I'
1/1/
\
\
110 0
Fig. 1
30 60 90 120 150 180mm.
O
60
120
180mm.
o
60
120
180mm.
Glucose, C-peptide and TRI curves of patients with hypothalamic obesity (K. G.: ;
A. P. r Gy. S. r =; I. Cs. r = ==) during per os glucose tolerance test related to those of normal-weight control subjets (± SD). E. N. r
Downloaded by: Collections and Technical Services Department. Copyrighted material.
Table 2
Exp. Clin. Endocrinol. 96 (1990) 1
86
Table 3 Overall data of the carbohydrate and insulin metabolism
E
C-
IRI
ZC-peptide
E
ZIRI
ZIRI
SIB% IBC of erythrocytes
Glucose peptide C-peptide (mmol,'l) (nmol/l) (nmol/l) (nmol/l) (nmolfl) K. G. E. N. A. P. Gy. S. I. Cs. Control
(n = 10)
29.1 37.3 27.9 29.4 31.9
3.36 1.83 1.12 3.23 3.10
0.112 0.242 0.220
32.8
0.50 0.20
± SD 4.2
27.80 17.48 15.10
(pmo!!!)
-
0.110 >56.00
2.70 3.32 4.91 3.44 3.82
0.054 0.036
8.52 3.70
1.48 0.45
5.0
(n = 7) 6.5
7.5
1.3
0.6
0.4
0.135* 0.070
'23.94**
8.92** 3.63
3.1* 1.6
0.122 > 56.10
10.3 5.3 3.1
>14.7
5.5 4.6 6.3 5.9
3.4 3.1 4.5 4.6
> 16.3
Obesity due to hypercalorization (n = 11) 40.9*
± SD 12.2
1.14** 0.32
10.91
(n = 9) 39*5 0.4
3.5 0.3
* p < 0.05, ** p < 0.01 between O and control group
TRI. Fasting TRI levels were significantly higher in the HO group than in the controls, but not higher than in the O group. Moreover, during OGTT, TRI curves were higher in HO patients than in the controls, but significantly lower than in the O group (2'IRI).
C-pep tide/JR I. The ratio of integrated values of the two peptides corresponded n one of our subjects to that of the control group (5.0 1.3), in another case to that of the O group (3.1.± 1.6); in K. G., Gy. S., and I. Cs. the ratio was very high. SIB % and IBC. SIB% of erythrocytes in each HO patient showed similar values as those of the controls (6.5 + 0.6%) - except A. P. - in contradiction to patients with excess weight (3.9 j 0.4), however, IBC calculated with Scatchard analysis was definitely lower ( = 3.87 pmol/l) than the values in the control group (7.5 +, 0.4 pmol/l) and corresponded to theO group (3.5 + 0.3) (Table 3). The line put to Scatchard curves is steeper in patients with HO than iii the control and O group (Fig. 2). Discussion
All patients were sent to our hospital because of extreme obesity, and their diencephalic damage was supported by CT, EEG and dysfunction of the hypothalamic-pituitary system. Increased function of the pituitary-adrenal axis was not detected in any patient. Hetherington and Hanson (1940) were the first to produce diencephalic obesity in laboratory animals by nuci. ventromedialis (VMN) lesion. This intervention results in hyperphagia, obesity and hyperinsulinism (Anand and Brobeck, 1951; King and Frohman, 1985). Opinions differ about the pathomechanism of this process. According to
Downloaded by: Collections and Technical Services Department. Copyrighted material.
Fasting
Initials
L. BLATNIOZKY et al., Hypothalamic Obesity and insulin Metabolism Sxl09erythrocytes/ml
SIB% 7
87
bound insutinxl02 free
6
A.
B.
6
S
Scatchard analysis
S.
5-
S.
\
32-
1234567891011
bour insulin
12,; 0.1
1.0
(flr8) Fig. 2
10
i2
-. (fl9)
insulin (nmot/L)
A. Specific insulin binding to erythrocytes in normal-weight control patients (), in obese
. --) and ones with hypothalamic obesity ( - and changes in the presence of unlabelled insulin increasing concentration. B. Binding capacity of the erythrocyts' receptors. Total insulin quantity bound by cells is represented on the horizontal axis; bound and free insulin ratio on the vertical axis. The line put to the initial, steep section of the curve and intersectioj of the horizontal axis indicates binding capacity of the high-affinity receptor group. Steepness of the line reflects affinity.
children ( .
Bray et al. (1981) lesion of VMN is followed by changes in the balance of the vegetative nervous system for vagus tone. Role of the opiate system cannot be excluded from the pathomechanism (Çenazzani et al., 1986; Baranowska et al., i987). Bobbioni and Jeanreunaud (1982) as well as Moltz et al. (1977) produced insulin release in rats by hypothalamic extracts. Lautala et al. (1986) could produce insulin release from the islets of Lan-
gerhans perfused by peptides extracted from the serum of patients with Prader-Willi syndromes. Martin and coworkers called this isolated peptide "insulin glucagon liberin" (Martin et al. 1981; Brouwer et al., 1982). In childhood obesity hyperinsulinism is a well-known phenomenon (Bonora et al., 1984; Blatniczky et al., 1985). Hypothalamic origin of hyperinsulinism in subjects with Prader-Willi syndrome was proved by Martin (1984) with TRI determination during OGTT. Determining the B-cell response well reflecting CP (Beiseher et al., 1975; florwitz et al., 1975; Polonsky and Rubenstein, 1984), TRI and SIB% of erythrocytes (Blatniczky et al., 1986) we proved that hyperinsulinism in O is partly absolute - due to the
hypersecretion of B-cells - and partly relative due to the "receptor down effect". According to the results of Bonora el al. (1986) we therefore concluded that the knowledge of serum IRI level per se does not give information about its origin (Blatniczky et al., 1985). Fasting CP levels were only slightly elevated in extremely O children. However, in patients with HO, except one subject, definitely high basal CP quantities were detected. Our observation suggests that in diencephalic obesity hyperinsulinemia is caused by primary hypersecretion. Individual CP curves during OGTT show hyperplasia of different degree in the islets of Langerhans, which have been formed for years (Kennedy and Parker, 1963; Stáló, 1967; Martin et al., 1974).
Downloaded by: Collections and Technical Services Department. Copyrighted material.
4-
88
Exp. Clin. Endocrino!. 96 (1990) 1
.X3P/21R1 ratio as well as SIB% of erythrocytes are suppressed in extremely obese children. Conversely the ratio of the two peptides and SIB% in subjects with diencephalic obesity corresponds to those with normal weight. These data appear to reinforce our previous opinion (Blatniczky et al., 1985; Blatniczky et al., 1986) that OP/'IRI ratio gives indirect information about insulin receptor function. In Scatchard analysis the line put to the points of low concentration is steeper in children with HO than in receptor groups binds insulin with higher affinity. We therefore conclude that in patients with HO, despite a decreased number of high-affinity binding sites, the increased affinity with unchanged SIB% can explain the high £CP/EIRI ratios calculated by insulin hypersecretion as well as the normal even lower glucose curves, and the slightly elevated basal TRI levels. Excellent glucose utilisation and hypoglycemic tendency may partly explain unsatisfied appetite of these patients.
Our results underline the suggestion that joint determination of CP and TRI is a useful method of diagnosis in obesity syndrome, it can explain the origin of elevated insulin with more accuracy and gives indirect information about insulin receptor function. High fasting CP level in childhood obesity suggests the possibility of diencephalic damage. In such cases together with an adequate clinical picture, carrying out functional examination of the hypothalamic-pituitary system should be reasonable. References ANAND, B. K.; BROBECK, J. R.: Localisation of a "feeding center" in the hypothalamus of the rat. Proc. Soc. Exp. Biol. Med. 77 (1951) 323-324. BARANOWSKA, B.; SINGR, S. P.; SoszYNsKI, P.; NovAxowsRi, J.; JESKE, W.: The role of opiate,
dopaminergic and adrenergic systems in the hypothalamo-pituitary disfunction in obesity. Acta Endocrino!. 116 (1987) 221-228. BEISCRER, W.; RAPITS, S.; KELLER, L.; HEINzKR, E.; SCHRÖDER, K. E.; PFEIFFER, E. F.: Characterization of the residual beta-cell function in diabetics by a new C-peptide radioimmunoassay. (Abstr.) Diabetologia 11 (1975) 332. BLATNICZKY, L.; KATJTZKY, L.; PIiTER, F.: Importance of C-peptide determination in obesity of childhood. (Abstr.) Acta Endocrino!. 109 (1985) 65. BLATMOEKY, L.; K.ATJTZKY, L.; MUzsNAI, A.; PIiTER, F.: Evaluation of insulin metabolism by
means of C-peptide and insulin determination. (Abstr.) 25th Ann. Meeting of ESPE - Zürich (198G) 135.
B0BBIONI, E.; JRANREUNAIÇD, B.: Effect of rat hypothalamic extract administration on insulin
secretion in vivo. Endocrinology 110 (1982) 631-636. BONORA, E.; ZAVARONI, I.; Bausciji, F.; ALpI, O.; PEZZAROSSA, A.; GUERRA, L.; DALL'AGLIO,
E.; COSCELLI, C.; BUTTURINI, U.: Peripheral hyperinsulinemia of simplex obesity: pancreatic-
hypersecretion or impaired insulin metabolism? J. Clin. Endocrino!. Metab. 59 (1984) 11211127. BoRonA, E.; ZAvAR0NI, I.; MAicICARDI, V.; COSCELLI, C.; BUTTUIUNI, [J.: Further evidence
that insulin metabolism is a major determinant of peripheral insulin response to orn! glucose in subjects with mild glucose intolerance. J. Endocrino!. Invest. 9 (1986) 371-374. BRAY, G. A.; TROUE, S.; NISHIZAWA, Y.: Hypothalamic obesity. The autonomie hypothesis and the lateral hypothalamus. Diabetologia 20 (1981) 366-377. BROUWER, G. H.; LAMPrEY, M. S.; MARTIN, J. M.: Isolation and partial characterization of insulin-glucagon !iberin from bovine hypothalamus. Life Sei. 30 (1982) 703 710. DtTNAIF, A.; MANDELI, J.; FLUKE, H.; DOBRJANSKY, A.: The impact of obesity and chronic hyperinsulinemia on gonadotropin release and gonada! steroid secretion in the polycystic ovary syndrome. J. Clin. Endocrino!. Metab. 66 (1988) 131-139.
Downloaded by: Collections and Technical Services Department. Copyrighted material.
normal-weight subjects. However, IBC of erythrocytes - with normal SIB% - is lower than in the control group. This indicates that a lower number of high-affinity
L. BLATNICZKY et al., Hypothalamic Obesity and Insulin Metabolism
89
[12] GAMBHIR, K. .K; ARCHER, J. A.; CARTER, L.: Insulin radioreceptor assay for human erythrocytes. Clin. Chem. 23 (1977) 1590-1595. ¡113] GENAZZINI, A. R.; FACCIIINETTI, F.; PETRAGLIA, C.; PINTOR, C.; CORDA, R.: Hyperendorphi-
nemia in obese children and adolescents. J. Clin. Endocrinol. Metab. 62 (1986) 36-40. GOLDMAN, J. K.; SCHNATZ, J. D.; BERNARDIS, L. L.; FROHMAN, L. A.: In vivo and in vitro metabolism in hypothalamic obesity. Diabetologia 8 (1972) 160-164. HAN, P. W.; FROHMAN, L. A.: Hyperinsulinemia in tube-fed hypophysectomized rats bearing hypothalamic lesions. Am. J. Physiol. 219 (1970) 1632-1636. HRTI*ERINGTON, A. W.; HANSON, S. W.: Hypothalamic lesions and adiposity in rats. Anat. Reo. H0RwITZ, D. L.; STARR, J. I.; MAKO, M. E.; BLACRARD, W. G.; RUBENSTEIN, A. H.: Proinsulin,
insulin and C-peptide concentrations in human portal and peripheral blood. J. Clin. Invest. 55 (1975) 1278-1283. KENNEDy, G. C.; PARKER, R. A.: The islets of Langerhans in rats with hypothalamic obesity.
Lancet II (1963) 981-982. KING, B. M.; FRORMAN, L. A.: Nonirritative lesions of VMH: effects on plasma insulin, obesity
and hyperreactivity. Am. J. Physiol. 248 (1985) 669-675. LAUTALA, P.; KNJP, M.; AKERBLOM, H. K.; KOUVALAINRN, K.; MARTIN, J. M.: Serum insulin-
releasing activity and the Prader-Willi syndrome. Acta Endocrinol. 110 (1986) 416 421. LOCRART-EWART, R. B.; MOR. C.; MARTIN, J. M.: Neuroendocrine control of insulin secretion.
Diabetes 25 (1976) 96 100. MARTIN, J. M.; KONIJNENDIJR, W.; BOUMAN, P. R.: Insulin and growth hormone secretion in
rats with ventromedial hypothalamic lesions maintained on restricted food intake. Diabetes 23 (1974) 203-208. MARTIN, J. M.; GRIMES, L. J.; MOK, C.; BROUWER, G.: Hypothalamic modulation of insulin
secretion and fat-cell metabolism. Acta Physiol. Lat. Am. 31 (1981) 43-49. M.RTIN, J. M.: The neuro-insular axis in the pathogenesis of obesity. Acta Univ. OuI. D. 122. Med. Interna et Paediatr. 23 (1984) 9-20. MOLTZ, J. H.; FAWCETT, C. P.; MCCANN, S. M.; DOBBS, R. H.; UNGER, R. H.: The hypotha-
lamic-pancreatic axis: evidence for a neurohumoral pathway in the control of the release of insulin and glucagon. Endocrinol. Res. Comm. 2 (1975) 537-547. MOLTZ, J. H.; BOBBS, R. E.; MCCANN, S. M.; FAWCETT, C. P.: Effects of hypothalamic factors
on insulin and glucagon release from the islets of Langerhans. Endocrinology 101 (1977) 196202.
NATIONAL DIABETES DATA GROUP: Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance. Diabetes 28 (1979) 1039-1057. POLONSKY, K. S.; RUBENSTEIN, A. H.: C-peptide as a measure of the secretion and hepatic extraction of insulin. Pitfalls and limitations. Diabetes 33 (1984) 486-494. SCATCHARD, G.: The attraction of proteins for small molecules and ions. Ann. N.Y. Acad. Sei. 51 (1949) 660-672. STÁLÓ, G.: Electron microscopic investigation of acinoinsular transformation in the rat. Acta biol. Acad. Sci. hung. 18 (1967) 323-333. WAJCHENBERG, B. L.; GIANELLA-NETO, D.; LERARIO, A C ; MARCONDES, L. Y.; OHNUMA, L. Y.:
Role of obesity and hyperinsulinemia in the insulin resistance of obese subjects with the clinical trial of polycystic ovaries, hirsutism and acanthosis nigricans. Horm. Res. 29 (1988) 7-13. YORK, D. A.; BRAY, G. A.: Dependence of hypothalamic obesity on insulin, the pituitary and the adrenal gland. Endocrinology 90 (1972) 885-894. (Accepted 28 August 1989)
Author's address: Dr. L. BLATNICZKY, Buda Children's Hospital, 23 POB 14, Budapest, Hungary
Downloaded by: Collections and Technical Services Department. Copyrighted material.
78 (1940) 149-172.
J. A. Barth, Leipzig
Buda Children's Hospital (Head: Prof. Dr. F. Péter) and "Korányi" Institute of TBC and Pulmonology' (Head: Prof. Dr. O. Schweiger), Budapest/Hungary
Insulin Metabolism in Hypothalamic Obesity With 2 Figures
Summary. Serum C-peptide and Immunoreactive Insulin (TRI) level was measured during per os glucose tolerance test as well as fasting specific insulin binding percentage and capacity of erythro-
cytes in hypothalamic obesity and in obese children due to hypercalorization, and was compared with ideal-weight controls. Integral values of curves (27) and EC-peptide/271R1 ratios were calculated.
In 4 cases fasting C-peptide content was substantially increased as compared to the other groups. The data suggest that hyperinsulinism in diencephalic obesity is primary. The ratio of the two peptides was normal or increased; insulin binding % of erythrocytes corresponded to that of the control group, which explains in these cases normal or favourable glucose metabolism. It is thought that in obese
children high fasting C-peptide levels with an adequate clinical picture can indicate the functional examination of the hypothalamic-pituitary system. £C-peptideJL'TRI ratio differing from normal indirectly shows the changes of receptor function. Key words: Hypothalamic obesity - C-peptide - Immunoreactive insulin - Insulin receptor
Introduction It has been widely assumed that genetic factors and anabolic-oriented shift in energy balance have a basic role in the pathogenesis of obesity. Moreover, it is becoming clearer f hat obesity may result in the dysfunction of the hypothalamic-pituitary system (York and Bray, 1972; Dunaif et al., 1988; Wajchenberg et al., 1988). It has been known since the first experiments of Hetherington and Ranson (1940) that hyperbulia and hyperphagy caused by destruction of the hypothalamic ventromedial nuclei (VMN) results in excessive obesity (Anand and Brobeck, 1951; Goldman et al., 1972). In the background of hyperbulia neurohumoral (Moltz et al., 1975; LockartEwart et al., 1976; Martin et al., 1981) and/or neuronic (Bray et al., 1981) effects are suspected. According to the general opinion the excess appetite in hypothalamic obesity (HO) is due to hyperinsulinemia (Han and Frohman, 1970; Martin, 1984). High fasting insulin level appeared to prove this fact. In previous studies C-peptide (CP) and Immunoreactive Insulin (TRI) determination was repeatedly performed during per os glucose tolerance test (OGTT) as well as the specific insulin binding percentage (SIB%) of ery-
throcytes in children with obesity due to hypercalorization (0) and without or with biguanides treatment (Blatniczky et al., 1985). It has been found that serum IRI level per se reveals no information about the reasons of the tendency of its quantities. A difference in insulin metabolism might depend on a different functional status of insulin receptors in various tissues (Bonora et al., 1986). Our publication assessesthe formation of
B-cell functional efficiency detected by CP determination in children with HO, and examines whether hyperinsulinism has a primary effect in this syndrome.
Downloaded by: Collections and Technical Services Department. Copyrighted material.
L. BLATNICZKY, L. KAUTZKY1 and F. PÉTER
84
Exp. Clin. Endocrinol. 96 (1990) 1
Materials and Methods In the past years 5 obese children (1 boy, 4 girls) have been examined at our outpatient clinic, whose HO syndrome was proved by anamnesis, clinical symptoms and the examinations performed
(Table 1). The capacity of the hypothalamic-pituitary system was examined (HGH in ITT and L-Dopa test; TSH, Prolactin in TRH test; LH, FSH in GnRH test; ACTH, Cortisol in i.v. Methyrapone test). Visual field and EEG examinations were performed in every case, CT in three cases Children were investigated after overnight starvation. 1.75 g/kg (max. 150 g) of glucose was administered orally and capillary glucose (Galenopharm-glucose oxidase), serum CP (Mallinckrodt Diagnostica-RIA) and TRI (Izinta-RIA) levels (in case K. G.: CP: 0, 60 and 150 mm) were determined every 30 min for 180 min. ECPf2'IRI ratio was determined by calculating integral values of the curves (E). These results were compared with the data of 10 normal-weight children aged 9-14 years and to those of 11 children with O (Table 1). In four children with HO SIB% of erythrocytes was determined with the method of Gambhir et al. (1977) and the insulin binding capacity (IBC) in the highaffinity receptor group was calculated with Scatchard analysis (Scatchard, 1949). Data obtained thereby were compared with those of 8 normal-weight children aged 8-15 years as well as with those of 9 obese children of the same age. Table 1 Main data of patients with hypothalamic obesity
Initials
Sex
Height Length
Age
(year)
K. G.
4
(cm)
age (year)
Weight Weigth
Diagnosis
for length (kg)
(SD)
132
9
36
2.8
E. N.
12 0/12
164
> 18
144
11.7
A. P.
13
167
> 18
121
8.0
Gigantism Tu. suprasellaris Adiposogigantism Diabetes insipidus
Mental retardation 112
Adiposogigantism
Mental retardation Gy. S.
15 /12
I. Cs.
17 6/12
178
168
> 18
>18
142
7.8
115
7.3
5.7 1.9
Adiposogigantism
Mental retardation Hypothalamic-pituitary dysfunction Diabetes insipidus Mental retardation
Obese children due to hypercalorization (n = 11)
i
± SD
128/a
163
15
98
1/l2
6
2
13
Results All children with HO were extremely obese, except A.G. who, however, put on 6 kg
in 4 weeks after the removal of a mixed-cellular (GH and Prolactin) suprasellar hypothalamic tumor. None of our patients displayed hyperfunction of the ACTH-adrenal axis. Multiple dysfunction was detected in one case; hyperprolactinemia in three cases. EEG showed diffuse cerebral electric dysfunction, except I. Cs.; CT suggested the possibility of diencephalie damage in all the patients examined (Table 2).
Downloaded by: Collections and Technical Services Department. Copyrighted material.
(Table 2).
85
L. BLATNICZKY et al., Hypothalamic Obesity and Insulin Metabolism
Informative data on the function of the hypothalamic-pituitary system in our patients
Initials HGH capacity TSH capacity ACTH rhythm Prolactin capacity LII capacity FSH capacity
K. G.
E. N.
A. P.
N N
N N N
N N N
t
N N N uncertain
1'
N N positive positive dwindled
CT
EEG* Visual field
N N uncertain positive N
N = normal, tt = increased-decreased capacity,
Gy. S.
I. Cs.
N N N
N
N N
positive dwindled
positive
N N
N
= no examination performed, * = positive
EEG diagnosis in each case indicated discrete diffuse cerebral damage
Glucose. During OGTT impaired glucose tolerance (National Diabetes Data Group, 1979) was found only in one patient (E. N.) (Fig. 1). In two cases normal and inK.G. and Gy. S. definitely decreased glucose response was found. C - pept ide. Fasting CP quantities were definitely higher in all patients with HO than in the control group, and in four cases they were higher than in the O group (Fig. 1, Table 3). During OGTT significant CP release was detected in each patient with HO and in two cases these levels were higher than the maximum detect- except K.G. able value of the RIA-kit (9.0 nmol/l). ECP level was higher in all patients than in the control group.
Serum C-peptide
>1 B
1
Capillary-glucose (mmol/l)
Serum RI
(nmol/i)
(n mol/i)
1.75g/kg glucose
1.75g/kg glucose
-8
1 1.75 g/kg glucose
I -4
I'
1/1/
\
\
110 0
Fig. 1
30 60 90 120 150 180mm.
O
60
120
180mm.
o
60
120
180mm.
Glucose, C-peptide and TRI curves of patients with hypothalamic obesity (K. G.: ;
A. P. r Gy. S. r =; I. Cs. r = ==) during per os glucose tolerance test related to those of normal-weight control subjets (± SD). E. N. r
Downloaded by: Collections and Technical Services Department. Copyrighted material.
Table 2
Exp. Clin. Endocrinol. 96 (1990) 1
86
Table 3 Overall data of the carbohydrate and insulin metabolism
E
C-
IRI
ZC-peptide
E
ZIRI
ZIRI
SIB% IBC of erythrocytes
Glucose peptide C-peptide (mmol,'l) (nmol/l) (nmol/l) (nmol/l) (nmolfl) K. G. E. N. A. P. Gy. S. I. Cs. Control
(n = 10)
29.1 37.3 27.9 29.4 31.9
3.36 1.83 1.12 3.23 3.10
0.112 0.242 0.220
32.8
0.50 0.20
± SD 4.2
27.80 17.48 15.10
(pmo!!!)
-
0.110 >56.00
2.70 3.32 4.91 3.44 3.82
0.054 0.036
8.52 3.70
1.48 0.45
5.0
(n = 7) 6.5
7.5
1.3
0.6
0.4
0.135* 0.070
'23.94**
8.92** 3.63
3.1* 1.6
0.122 > 56.10
10.3 5.3 3.1
>14.7
5.5 4.6 6.3 5.9
3.4 3.1 4.5 4.6
> 16.3
Obesity due to hypercalorization (n = 11) 40.9*
± SD 12.2
1.14** 0.32
10.91
(n = 9) 39*5 0.4
3.5 0.3
* p < 0.05, ** p < 0.01 between O and control group
TRI. Fasting TRI levels were significantly higher in the HO group than in the controls, but not higher than in the O group. Moreover, during OGTT, TRI curves were higher in HO patients than in the controls, but significantly lower than in the O group (2'IRI).
C-pep tide/JR I. The ratio of integrated values of the two peptides corresponded n one of our subjects to that of the control group (5.0 1.3), in another case to that of the O group (3.1.± 1.6); in K. G., Gy. S., and I. Cs. the ratio was very high. SIB % and IBC. SIB% of erythrocytes in each HO patient showed similar values as those of the controls (6.5 + 0.6%) - except A. P. - in contradiction to patients with excess weight (3.9 j 0.4), however, IBC calculated with Scatchard analysis was definitely lower ( = 3.87 pmol/l) than the values in the control group (7.5 +, 0.4 pmol/l) and corresponded to theO group (3.5 + 0.3) (Table 3). The line put to Scatchard curves is steeper in patients with HO than iii the control and O group (Fig. 2). Discussion
All patients were sent to our hospital because of extreme obesity, and their diencephalic damage was supported by CT, EEG and dysfunction of the hypothalamic-pituitary system. Increased function of the pituitary-adrenal axis was not detected in any patient. Hetherington and Hanson (1940) were the first to produce diencephalic obesity in laboratory animals by nuci. ventromedialis (VMN) lesion. This intervention results in hyperphagia, obesity and hyperinsulinism (Anand and Brobeck, 1951; King and Frohman, 1985). Opinions differ about the pathomechanism of this process. According to
Downloaded by: Collections and Technical Services Department. Copyrighted material.
Fasting
Initials
L. BLATNIOZKY et al., Hypothalamic Obesity and insulin Metabolism Sxl09erythrocytes/ml
SIB% 7
87
bound insutinxl02 free
6
A.
B.
6
S
Scatchard analysis
S.
5-
S.
\
32-
1234567891011
bour insulin
12,; 0.1
1.0
(flr8) Fig. 2
10
i2
-. (fl9)
insulin (nmot/L)
A. Specific insulin binding to erythrocytes in normal-weight control patients (), in obese
. --) and ones with hypothalamic obesity ( - and changes in the presence of unlabelled insulin increasing concentration. B. Binding capacity of the erythrocyts' receptors. Total insulin quantity bound by cells is represented on the horizontal axis; bound and free insulin ratio on the vertical axis. The line put to the initial, steep section of the curve and intersectioj of the horizontal axis indicates binding capacity of the high-affinity receptor group. Steepness of the line reflects affinity.
children ( .
Bray et al. (1981) lesion of VMN is followed by changes in the balance of the vegetative nervous system for vagus tone. Role of the opiate system cannot be excluded from the pathomechanism (Çenazzani et al., 1986; Baranowska et al., i987). Bobbioni and Jeanreunaud (1982) as well as Moltz et al. (1977) produced insulin release in rats by hypothalamic extracts. Lautala et al. (1986) could produce insulin release from the islets of Lan-
gerhans perfused by peptides extracted from the serum of patients with Prader-Willi syndromes. Martin and coworkers called this isolated peptide "insulin glucagon liberin" (Martin et al. 1981; Brouwer et al., 1982). In childhood obesity hyperinsulinism is a well-known phenomenon (Bonora et al., 1984; Blatniczky et al., 1985). Hypothalamic origin of hyperinsulinism in subjects with Prader-Willi syndrome was proved by Martin (1984) with TRI determination during OGTT. Determining the B-cell response well reflecting CP (Beiseher et al., 1975; florwitz et al., 1975; Polonsky and Rubenstein, 1984), TRI and SIB% of erythrocytes (Blatniczky et al., 1986) we proved that hyperinsulinism in O is partly absolute - due to the
hypersecretion of B-cells - and partly relative due to the "receptor down effect". According to the results of Bonora el al. (1986) we therefore concluded that the knowledge of serum IRI level per se does not give information about its origin (Blatniczky et al., 1985). Fasting CP levels were only slightly elevated in extremely O children. However, in patients with HO, except one subject, definitely high basal CP quantities were detected. Our observation suggests that in diencephalic obesity hyperinsulinemia is caused by primary hypersecretion. Individual CP curves during OGTT show hyperplasia of different degree in the islets of Langerhans, which have been formed for years (Kennedy and Parker, 1963; Stáló, 1967; Martin et al., 1974).
Downloaded by: Collections and Technical Services Department. Copyrighted material.
4-
88
Exp. Clin. Endocrino!. 96 (1990) 1
.X3P/21R1 ratio as well as SIB% of erythrocytes are suppressed in extremely obese children. Conversely the ratio of the two peptides and SIB% in subjects with diencephalic obesity corresponds to those with normal weight. These data appear to reinforce our previous opinion (Blatniczky et al., 1985; Blatniczky et al., 1986) that OP/'IRI ratio gives indirect information about insulin receptor function. In Scatchard analysis the line put to the points of low concentration is steeper in children with HO than in receptor groups binds insulin with higher affinity. We therefore conclude that in patients with HO, despite a decreased number of high-affinity binding sites, the increased affinity with unchanged SIB% can explain the high £CP/EIRI ratios calculated by insulin hypersecretion as well as the normal even lower glucose curves, and the slightly elevated basal TRI levels. Excellent glucose utilisation and hypoglycemic tendency may partly explain unsatisfied appetite of these patients.
Our results underline the suggestion that joint determination of CP and TRI is a useful method of diagnosis in obesity syndrome, it can explain the origin of elevated insulin with more accuracy and gives indirect information about insulin receptor function. High fasting CP level in childhood obesity suggests the possibility of diencephalic damage. In such cases together with an adequate clinical picture, carrying out functional examination of the hypothalamic-pituitary system should be reasonable. References ANAND, B. K.; BROBECK, J. R.: Localisation of a "feeding center" in the hypothalamus of the rat. Proc. Soc. Exp. Biol. Med. 77 (1951) 323-324. BARANOWSKA, B.; SINGR, S. P.; SoszYNsKI, P.; NovAxowsRi, J.; JESKE, W.: The role of opiate,
dopaminergic and adrenergic systems in the hypothalamo-pituitary disfunction in obesity. Acta Endocrino!. 116 (1987) 221-228. BEISCRER, W.; RAPITS, S.; KELLER, L.; HEINzKR, E.; SCHRÖDER, K. E.; PFEIFFER, E. F.: Characterization of the residual beta-cell function in diabetics by a new C-peptide radioimmunoassay. (Abstr.) Diabetologia 11 (1975) 332. BLATNICZKY, L.; KATJTZKY, L.; PIiTER, F.: Importance of C-peptide determination in obesity of childhood. (Abstr.) Acta Endocrino!. 109 (1985) 65. BLATMOEKY, L.; K.ATJTZKY, L.; MUzsNAI, A.; PIiTER, F.: Evaluation of insulin metabolism by
means of C-peptide and insulin determination. (Abstr.) 25th Ann. Meeting of ESPE - Zürich (198G) 135.
B0BBIONI, E.; JRANREUNAIÇD, B.: Effect of rat hypothalamic extract administration on insulin
secretion in vivo. Endocrinology 110 (1982) 631-636. BONORA, E.; ZAVARONI, I.; Bausciji, F.; ALpI, O.; PEZZAROSSA, A.; GUERRA, L.; DALL'AGLIO,
E.; COSCELLI, C.; BUTTURINI, U.: Peripheral hyperinsulinemia of simplex obesity: pancreatic-
hypersecretion or impaired insulin metabolism? J. Clin. Endocrino!. Metab. 59 (1984) 11211127. BoRonA, E.; ZAvAR0NI, I.; MAicICARDI, V.; COSCELLI, C.; BUTTUIUNI, [J.: Further evidence
that insulin metabolism is a major determinant of peripheral insulin response to orn! glucose in subjects with mild glucose intolerance. J. Endocrino!. Invest. 9 (1986) 371-374. BRAY, G. A.; TROUE, S.; NISHIZAWA, Y.: Hypothalamic obesity. The autonomie hypothesis and the lateral hypothalamus. Diabetologia 20 (1981) 366-377. BROUWER, G. H.; LAMPrEY, M. S.; MARTIN, J. M.: Isolation and partial characterization of insulin-glucagon !iberin from bovine hypothalamus. Life Sei. 30 (1982) 703 710. DtTNAIF, A.; MANDELI, J.; FLUKE, H.; DOBRJANSKY, A.: The impact of obesity and chronic hyperinsulinemia on gonadotropin release and gonada! steroid secretion in the polycystic ovary syndrome. J. Clin. Endocrino!. Metab. 66 (1988) 131-139.
Downloaded by: Collections and Technical Services Department. Copyrighted material.
normal-weight subjects. However, IBC of erythrocytes - with normal SIB% - is lower than in the control group. This indicates that a lower number of high-affinity
L. BLATNICZKY et al., Hypothalamic Obesity and Insulin Metabolism
89
[12] GAMBHIR, K. .K; ARCHER, J. A.; CARTER, L.: Insulin radioreceptor assay for human erythrocytes. Clin. Chem. 23 (1977) 1590-1595. ¡113] GENAZZINI, A. R.; FACCIIINETTI, F.; PETRAGLIA, C.; PINTOR, C.; CORDA, R.: Hyperendorphi-
nemia in obese children and adolescents. J. Clin. Endocrinol. Metab. 62 (1986) 36-40. GOLDMAN, J. K.; SCHNATZ, J. D.; BERNARDIS, L. L.; FROHMAN, L. A.: In vivo and in vitro metabolism in hypothalamic obesity. Diabetologia 8 (1972) 160-164. HAN, P. W.; FROHMAN, L. A.: Hyperinsulinemia in tube-fed hypophysectomized rats bearing hypothalamic lesions. Am. J. Physiol. 219 (1970) 1632-1636. HRTI*ERINGTON, A. W.; HANSON, S. W.: Hypothalamic lesions and adiposity in rats. Anat. Reo. H0RwITZ, D. L.; STARR, J. I.; MAKO, M. E.; BLACRARD, W. G.; RUBENSTEIN, A. H.: Proinsulin,
insulin and C-peptide concentrations in human portal and peripheral blood. J. Clin. Invest. 55 (1975) 1278-1283. KENNEDy, G. C.; PARKER, R. A.: The islets of Langerhans in rats with hypothalamic obesity.
Lancet II (1963) 981-982. KING, B. M.; FRORMAN, L. A.: Nonirritative lesions of VMH: effects on plasma insulin, obesity
and hyperreactivity. Am. J. Physiol. 248 (1985) 669-675. LAUTALA, P.; KNJP, M.; AKERBLOM, H. K.; KOUVALAINRN, K.; MARTIN, J. M.: Serum insulin-
releasing activity and the Prader-Willi syndrome. Acta Endocrinol. 110 (1986) 416 421. LOCRART-EWART, R. B.; MOR. C.; MARTIN, J. M.: Neuroendocrine control of insulin secretion.
Diabetes 25 (1976) 96 100. MARTIN, J. M.; KONIJNENDIJR, W.; BOUMAN, P. R.: Insulin and growth hormone secretion in
rats with ventromedial hypothalamic lesions maintained on restricted food intake. Diabetes 23 (1974) 203-208. MARTIN, J. M.; GRIMES, L. J.; MOK, C.; BROUWER, G.: Hypothalamic modulation of insulin
secretion and fat-cell metabolism. Acta Physiol. Lat. Am. 31 (1981) 43-49. M.RTIN, J. M.: The neuro-insular axis in the pathogenesis of obesity. Acta Univ. OuI. D. 122. Med. Interna et Paediatr. 23 (1984) 9-20. MOLTZ, J. H.; FAWCETT, C. P.; MCCANN, S. M.; DOBBS, R. H.; UNGER, R. H.: The hypotha-
lamic-pancreatic axis: evidence for a neurohumoral pathway in the control of the release of insulin and glucagon. Endocrinol. Res. Comm. 2 (1975) 537-547. MOLTZ, J. H.; BOBBS, R. E.; MCCANN, S. M.; FAWCETT, C. P.: Effects of hypothalamic factors
on insulin and glucagon release from the islets of Langerhans. Endocrinology 101 (1977) 196202.
NATIONAL DIABETES DATA GROUP: Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance. Diabetes 28 (1979) 1039-1057. POLONSKY, K. S.; RUBENSTEIN, A. H.: C-peptide as a measure of the secretion and hepatic extraction of insulin. Pitfalls and limitations. Diabetes 33 (1984) 486-494. SCATCHARD, G.: The attraction of proteins for small molecules and ions. Ann. N.Y. Acad. Sei. 51 (1949) 660-672. STÁLÓ, G.: Electron microscopic investigation of acinoinsular transformation in the rat. Acta biol. Acad. Sci. hung. 18 (1967) 323-333. WAJCHENBERG, B. L.; GIANELLA-NETO, D.; LERARIO, A C ; MARCONDES, L. Y.; OHNUMA, L. Y.:
Role of obesity and hyperinsulinemia in the insulin resistance of obese subjects with the clinical trial of polycystic ovaries, hirsutism and acanthosis nigricans. Horm. Res. 29 (1988) 7-13. YORK, D. A.; BRAY, G. A.: Dependence of hypothalamic obesity on insulin, the pituitary and the adrenal gland. Endocrinology 90 (1972) 885-894. (Accepted 28 August 1989)
Author's address: Dr. L. BLATNICZKY, Buda Children's Hospital, 23 POB 14, Budapest, Hungary
Downloaded by: Collections and Technical Services Department. Copyrighted material.
78 (1940) 149-172.
