243 SHORT COMMUNICATIONS
Honn. Metab. Res. 9 (1977) 243-244
© Georg Thieme Verlag Stuttgart Inhibition by Mannose of Arginine-Induced Glucagon Secretion in the Isolated Perfused Rat Pancreas Y . Goto , Y . Seino, T. Taminato, S. Matsukura and H. Imura Third Division . Department of Medicine. University of Kobe . K obe. Japan
It is weil known that arginine-induced glucagon secretion from the perfused rat pancreas is enhanced by hypoglycemia, while it is suppressed by hyperglycemia (Gerich, Char/es and Grodsky 1974). This suggests the elose relationship between glucose and amino acids in regulating glucagon secretion. In our previous study, we demonstrated that fructose has an inhibitory effect on glucagon secretion and a stimulatory effect on insulin secretion induced by arginine (Goto. Seino, Taminato and Imura 1976). Although mannose, like glucose, stimulates insulin secretion (Grodsky. Batts. Bennet. Vcella, McWilliams and Smith 1963), the effect of mannose on glucagon secretion remains to be studied.
Therefore, we have investigated the effect of mannose on arginine-induced glucagon secretion in the perfused rat pancreas.
Results and Discussion As shown in Figure, mean glucagon levels in the portal vein effluent before arginine infusion were not significantly different in the presence or absence of mannose. The addition of arginine to the perfusate of glucose with mannose caused a biphasic increase in glucagon concentration with the first and se co nd peaks of 0.93 ± 0.31 and 0.29 ± 0.02 ng/ml (Mean ± S.E.) respectively, both of which were significantly lower than the corresponding glucagon peaks, elicited by arginine during the perfusion of 2.8 mM glucose alone. On the other hand, mean insulin levels before arginine infusion and the insulin responses to arginine were significantly exaggerated by the presence of mannose, as compared with that during the perfusion of 2.8 mM glucose alone. Addition of exogenous pork insulin to the perfusate had no effect on glucagon secretion before and after arginine infusion in the presence of 2.8 mM glucose.
Glucose
2.8 mM
2.8 mM
0- - -0
o I o
: .
I, ,r" )'
,-t------
N=lS
A- - - - -6
I "I .1... ____
...
5 10 nme(min)
Glucose 2.S
20
5
-_ .. ..-
-1
5
10
Time (min)
10
20
nme(min)
Fig. 1 Glucagon and insulin secretion induced by arginine in the presence of 2.8 mM glucose and in the presence of 16.7 mM mannose and 2.8 mM glucose. (Mean ± S.E.) Glucagon secretion induced by arginine in the presence of 2.8 mM glucose and in the presence of I /Jg/ml pork insulin and 2.8 mM glucose. (Mean ± S.E.) • p < 0.005 Rec.: 15 Dec. 1976
Ace.: 21 Feb. 1977
Downloaded by: Universite de Sherbrooke. Copyrighted material.
Materials and Methods The pancreas was isolated and perfused using a procedure described previously (Goto, Seino, Taminato and Imura 1976). In experiment I , the perfusion was perfonned with 2.8 mM glucose for 55 minutes as a control. The perfusions were performed using 16.7 mM mannose with 2.8 mM glucose and pork insulin 1 /Jg/ml with 2.8 mM glucose for 35 minutes, in experiments 2 and 3 respectively, following the preperfusion with 2.8 mM glucose over aperiod of 20 minutes. In all experiments I-arginine hydrochloride neutralized with 0.5 N NaOH was added through a side arm to give a final concentration of 38 mM over aperiod of 20 minutes after the first 35 minutes of each perfusion. Glucagon was detennined by radioimmunoassay with a tale adsorption technique (Sakurai and Imura 1973) using antiserum 30 K (purchased from the Diabetes Research Fund, University of Texas Southwestern, Dallas, Texas). Insulin was determined by polyethylene glycol radioimmunoassay (Desbuquois and Auerbach 1971). Results were analysed by Student's "t" test.
244
Short Communications
The present study demonstrated that mannose inhibited arginine-induced glucagon secretion in the perfused rat pancreas. The direct inhibitory effect of insulin on glucagon secretion could be ruled out, since exogenous insulin did not modify arginine-induced glucagon secretion, as presented in this study. Therefore, it is considered that mannose may inhibit arginine-induced glucagon secretion thPOugh its direct action on A cells. References Desbuquois, B., G.D. Auerbach: J. Clin. Endocrinol. Metab. 33: 732 (1971). - Gerich, J.E., M.A. Char/es, G.M. Grodsky: J. Clin. Invest. 54: 833 (1974). - Goto, Y., Y. Seino, T. Taminato, H. Imura: J. Endocr. 69: 295 (1976). - Goto, Y., Y. Seino, T. TamiMto, H. Imura: Horm. Metab. Res. 8: 240 (1976). - Grodsky, G.M., A.A. Batts, L.L. Benett, C. Vce/Ia, N.B. McWilliams, D.F. Smith: Amer. I. Physiol. 205: 638 (1963). - Sakurai, H., H. Imura: Iap. J. Nucl. Med. 10: 135 (1973).
Requests for reprints should be addressed to: Dr. Y. Goto, Third Division, Dept. Med., Univ. Kobe, Kobe (Japan)
Hormon. Metab. Res. 9 (1977) 244-245
© Georg Thieme Verlag Stuttgart
F. Damrnacco, F.M. Puca, N. Rigillo, S. Genco, L.M. Specchio, G. Chetrl, C. ToreIli, C. Mastrangelo, C. Candeliere and D. Galeone Clinica Pediatrica, Clinica Malattie Nervose e Mentali, Universita di Bari, Italy The onset of noctumal sleep is followed in man by a spontaneous release of growth hormone (hGH), strictly correlated with the slow-wave sleep (Takahashi, Kipnis and Daughaday 1968). However, the mechanisms controlling both deep sleep and the nocturnal hGH secretion in man remain still unelucidated. Adrenergic blockade (Lucke and GUck 1971) didt not influence this hGH secretion, which has been found increased by methysergide administration in man (Mende/son, Jacobs, Reichman, Othmer, Cryer, Trivedi and Daughaday 1975). In this report we describe the inhibitory effect showed by cyproheptadine on the sleep-enhanced growth hormone secretion in adult subjects. Materials and Methods Six normal male volunteers, aged 21 to 35 years, spent in the laboratory six night in two separate sessions. In each session two "adjustment" nights were followed by a sleep night study. After the control night, the subjects were given oraUy cyproheptadine, 12 mg/daY, for five days. During the fifth night of cyproheptadine administration a second sleep study was performed. Blood specimens for hGH determinations by double-antibody radioimmunoassay were coUected at 30 min intervals, starting at the onset of sleep and throughout the night, from a previously inserted venous catheter, in addition to all-night polygraphie recordings (EEG, EOG and EMG of chin muscles). Records were classified according to current international criteria (Rechtschaffen and Kaies 1968). Statistical evaluations were performed by analysis of variance after logaritmiclo transformation of hormonal data. 6
.JO
Percentoge of sleep ~toge~
•
:'Oormal
Results
SubJeot.
••
CJ beton C)'pro _after
20
~
_ _ be fore c.ypro
20
_._._&fter
0
....
ä..
During the control night a significant rise in plasma hGH concentration (range: 6-40 ng/ml; mean ± SEM: 12.70 ± 6.82 ng/ml) occurred in all subjects weil correlated with stages 3 and 4 of the non-REM sleep within the first 60 min after the onset of the sleep (Figure). On cyproheptadine night the highest hGH levels were found significantly reduced (mean ± SEM: 2.68 ± 1.53 ng/ml; p < 0,01 VS control night). As show in Figure, cyproheptadine administration, significantly increased delta sleep and reduced stage 2. Total REM sleep time remained unchanged.
E
Discussion
c
Present data show the inhibitory effect of cyproheptadine on the sleep-related hGH secretion in normal adults and confirm our previous data in three children (Dammacco, Rigillo, Zimbalatti, Brunetti, Scaramuzzi and Dammacco 1975). If cyproheptadine acts as anti-serotonin agent, our results suggest that serotoninergic mechanisms may playa stimulatory role in the sleep-enhanced hGH secretion. The dissociation caused by cyproheptadine between the increased delta sleep and the reduced hGH secretion seems also suggest that different monoaminorgie systems operate in inducing the two phenomena in man. It is possible, however, that in our study the increased delta sleep may be inversely related to the reduced hGH secretion induced by cyproheptadine.
~10
:r
"
5
.t:.
0
._._._._._._._.~
0
180
minutes
UO
360
of sleep
Figure. Plasma hGH levels and percentages of sleep stages during noctumal sleep in six adult subjects before and after cyproheptadine (cypro) administration. (Mean ± SEM; • = p < 0.05; •• = P < 0.01) Rec.: 19 Nov. 1976
Acc.: 21 Feb. 1977
Downloaded by: Universite de Sherbrooke. Copyrighted material.
Inhibitory Effect of Cyproheptadine Administration on the Sleep-Related Growth Hormone Secretion in Man*
Honn. Metab. Res. 9 (1977) 243-244
© Georg Thieme Verlag Stuttgart Inhibition by Mannose of Arginine-Induced Glucagon Secretion in the Isolated Perfused Rat Pancreas Y . Goto , Y . Seino, T. Taminato, S. Matsukura and H. Imura Third Division . Department of Medicine. University of Kobe . K obe. Japan
It is weil known that arginine-induced glucagon secretion from the perfused rat pancreas is enhanced by hypoglycemia, while it is suppressed by hyperglycemia (Gerich, Char/es and Grodsky 1974). This suggests the elose relationship between glucose and amino acids in regulating glucagon secretion. In our previous study, we demonstrated that fructose has an inhibitory effect on glucagon secretion and a stimulatory effect on insulin secretion induced by arginine (Goto. Seino, Taminato and Imura 1976). Although mannose, like glucose, stimulates insulin secretion (Grodsky. Batts. Bennet. Vcella, McWilliams and Smith 1963), the effect of mannose on glucagon secretion remains to be studied.
Therefore, we have investigated the effect of mannose on arginine-induced glucagon secretion in the perfused rat pancreas.
Results and Discussion As shown in Figure, mean glucagon levels in the portal vein effluent before arginine infusion were not significantly different in the presence or absence of mannose. The addition of arginine to the perfusate of glucose with mannose caused a biphasic increase in glucagon concentration with the first and se co nd peaks of 0.93 ± 0.31 and 0.29 ± 0.02 ng/ml (Mean ± S.E.) respectively, both of which were significantly lower than the corresponding glucagon peaks, elicited by arginine during the perfusion of 2.8 mM glucose alone. On the other hand, mean insulin levels before arginine infusion and the insulin responses to arginine were significantly exaggerated by the presence of mannose, as compared with that during the perfusion of 2.8 mM glucose alone. Addition of exogenous pork insulin to the perfusate had no effect on glucagon secretion before and after arginine infusion in the presence of 2.8 mM glucose.
Glucose
2.8 mM
2.8 mM
0- - -0
o I o
: .
I, ,r" )'
,-t------
N=lS
A- - - - -6
I "I .1... ____
...
5 10 nme(min)
Glucose 2.S
20
5
-_ .. ..-
-1
5
10
Time (min)
10
20
nme(min)
Fig. 1 Glucagon and insulin secretion induced by arginine in the presence of 2.8 mM glucose and in the presence of 16.7 mM mannose and 2.8 mM glucose. (Mean ± S.E.) Glucagon secretion induced by arginine in the presence of 2.8 mM glucose and in the presence of I /Jg/ml pork insulin and 2.8 mM glucose. (Mean ± S.E.) • p < 0.005 Rec.: 15 Dec. 1976
Ace.: 21 Feb. 1977
Downloaded by: Universite de Sherbrooke. Copyrighted material.
Materials and Methods The pancreas was isolated and perfused using a procedure described previously (Goto, Seino, Taminato and Imura 1976). In experiment I , the perfusion was perfonned with 2.8 mM glucose for 55 minutes as a control. The perfusions were performed using 16.7 mM mannose with 2.8 mM glucose and pork insulin 1 /Jg/ml with 2.8 mM glucose for 35 minutes, in experiments 2 and 3 respectively, following the preperfusion with 2.8 mM glucose over aperiod of 20 minutes. In all experiments I-arginine hydrochloride neutralized with 0.5 N NaOH was added through a side arm to give a final concentration of 38 mM over aperiod of 20 minutes after the first 35 minutes of each perfusion. Glucagon was detennined by radioimmunoassay with a tale adsorption technique (Sakurai and Imura 1973) using antiserum 30 K (purchased from the Diabetes Research Fund, University of Texas Southwestern, Dallas, Texas). Insulin was determined by polyethylene glycol radioimmunoassay (Desbuquois and Auerbach 1971). Results were analysed by Student's "t" test.
244
Short Communications
The present study demonstrated that mannose inhibited arginine-induced glucagon secretion in the perfused rat pancreas. The direct inhibitory effect of insulin on glucagon secretion could be ruled out, since exogenous insulin did not modify arginine-induced glucagon secretion, as presented in this study. Therefore, it is considered that mannose may inhibit arginine-induced glucagon secretion thPOugh its direct action on A cells. References Desbuquois, B., G.D. Auerbach: J. Clin. Endocrinol. Metab. 33: 732 (1971). - Gerich, J.E., M.A. Char/es, G.M. Grodsky: J. Clin. Invest. 54: 833 (1974). - Goto, Y., Y. Seino, T. Taminato, H. Imura: J. Endocr. 69: 295 (1976). - Goto, Y., Y. Seino, T. TamiMto, H. Imura: Horm. Metab. Res. 8: 240 (1976). - Grodsky, G.M., A.A. Batts, L.L. Benett, C. Vce/Ia, N.B. McWilliams, D.F. Smith: Amer. I. Physiol. 205: 638 (1963). - Sakurai, H., H. Imura: Iap. J. Nucl. Med. 10: 135 (1973).
Requests for reprints should be addressed to: Dr. Y. Goto, Third Division, Dept. Med., Univ. Kobe, Kobe (Japan)
Hormon. Metab. Res. 9 (1977) 244-245
© Georg Thieme Verlag Stuttgart
F. Damrnacco, F.M. Puca, N. Rigillo, S. Genco, L.M. Specchio, G. Chetrl, C. ToreIli, C. Mastrangelo, C. Candeliere and D. Galeone Clinica Pediatrica, Clinica Malattie Nervose e Mentali, Universita di Bari, Italy The onset of noctumal sleep is followed in man by a spontaneous release of growth hormone (hGH), strictly correlated with the slow-wave sleep (Takahashi, Kipnis and Daughaday 1968). However, the mechanisms controlling both deep sleep and the nocturnal hGH secretion in man remain still unelucidated. Adrenergic blockade (Lucke and GUck 1971) didt not influence this hGH secretion, which has been found increased by methysergide administration in man (Mende/son, Jacobs, Reichman, Othmer, Cryer, Trivedi and Daughaday 1975). In this report we describe the inhibitory effect showed by cyproheptadine on the sleep-enhanced growth hormone secretion in adult subjects. Materials and Methods Six normal male volunteers, aged 21 to 35 years, spent in the laboratory six night in two separate sessions. In each session two "adjustment" nights were followed by a sleep night study. After the control night, the subjects were given oraUy cyproheptadine, 12 mg/daY, for five days. During the fifth night of cyproheptadine administration a second sleep study was performed. Blood specimens for hGH determinations by double-antibody radioimmunoassay were coUected at 30 min intervals, starting at the onset of sleep and throughout the night, from a previously inserted venous catheter, in addition to all-night polygraphie recordings (EEG, EOG and EMG of chin muscles). Records were classified according to current international criteria (Rechtschaffen and Kaies 1968). Statistical evaluations were performed by analysis of variance after logaritmiclo transformation of hormonal data. 6
.JO
Percentoge of sleep ~toge~
•
:'Oormal
Results
SubJeot.
••
CJ beton C)'pro _after
20
~
_ _ be fore c.ypro
20
_._._&fter
0
....
ä..
During the control night a significant rise in plasma hGH concentration (range: 6-40 ng/ml; mean ± SEM: 12.70 ± 6.82 ng/ml) occurred in all subjects weil correlated with stages 3 and 4 of the non-REM sleep within the first 60 min after the onset of the sleep (Figure). On cyproheptadine night the highest hGH levels were found significantly reduced (mean ± SEM: 2.68 ± 1.53 ng/ml; p < 0,01 VS control night). As show in Figure, cyproheptadine administration, significantly increased delta sleep and reduced stage 2. Total REM sleep time remained unchanged.
E
Discussion
c
Present data show the inhibitory effect of cyproheptadine on the sleep-related hGH secretion in normal adults and confirm our previous data in three children (Dammacco, Rigillo, Zimbalatti, Brunetti, Scaramuzzi and Dammacco 1975). If cyproheptadine acts as anti-serotonin agent, our results suggest that serotoninergic mechanisms may playa stimulatory role in the sleep-enhanced hGH secretion. The dissociation caused by cyproheptadine between the increased delta sleep and the reduced hGH secretion seems also suggest that different monoaminorgie systems operate in inducing the two phenomena in man. It is possible, however, that in our study the increased delta sleep may be inversely related to the reduced hGH secretion induced by cyproheptadine.
~10
:r
"
5
.t:.
0
._._._._._._._.~
0
180
minutes
UO
360
of sleep
Figure. Plasma hGH levels and percentages of sleep stages during noctumal sleep in six adult subjects before and after cyproheptadine (cypro) administration. (Mean ± SEM; • = p < 0.05; •• = P < 0.01) Rec.: 19 Nov. 1976
Acc.: 21 Feb. 1977
Downloaded by: Universite de Sherbrooke. Copyrighted material.
Inhibitory Effect of Cyproheptadine Administration on the Sleep-Related Growth Hormone Secretion in Man*
