Sex-related responses of beta-endorphin, ACTH, GH and PRL to cold exposure in humans G Gerra, R Volpi, R Delsignore, L Maninetti, R Caccavari, S Vourna, D Maestri, P Chiodera, G Ugolotti and V Coiro University Clinics of Internal Medicine, Endocrinology', University of Parma: Drug Addiction Service2 and RIA Laboratory', Hospital of Parma, Italy
Gerra G, Volpi R, Delsignore R, Maninetti L, Caccavari R, Vourna S, Maestri D, Chiodera P, Ugolotti G, Coiro V. Sex-related responses of beta-endorphin, ACTH, GH and PRL to cold exposure in humans. Acta Endocrinol 1992;126:24-8. ISSN 0001-5598
possible different
reaction between the male and the female to short-term exposure to stress were measured in eight normal men and eight women (ages 19\p=n-\24).The women were eumenorrheic and were tested in the follicular phase. Each subject, lightly clad, was required to remain for 30 min in a room at an ambient temperature of 2 5\s=deg\Cfollowed by a 30 min period in a cold room at 4\s=deg\C.A month later, control tests were carried out at a constant 25\s=deg\Ctemperature for 1 h in the same subjects. Skin temperature, heart rate, blood pressure and plasma levels of beta-endorphin, ACTH, cortisol, GH and PRL were measured before and after cold exposure in the two groups. Before the test, all examined parameters were similar in the two groups. During cooling, blood pressure rose and pulse rate decreased significantly in the men, but not in the women, whereas skin temperature dropped in both groups. However, after cold exposure skin temperature was significantly lower in the women than in the men. A slight, but not significant increase in beta-endorphin, ACTH, cortisol and GH levels was observed after cooling in the men, whereas the women showed significant increments of these hormones, When values of skin temperature were combined with the differential (after minus before cold test) hormonal values, significant negative correlations were found for beta-endorphin, ACTH, cortisol and GH. As observed by other authors, a significant and peculiar cold-induced decline in plasma PRL levels was observed in the men; by contrast, a slight, but not significant decrement of PRL was found in the women. Control tests at a constant 25\s=deg\Ctemperature did not show significant thermal, cardiovascular or hormonal changes in any subject. These data reflect stronger thermal, cardiovascular and PRL responses to cooling in men than in women. On the other hand, the women, but not the men, showed significant cold-stress\x=req-\ induced increments of beta-endorphin, ACTH and GH, suggesting that the more efficient adaptation to cold of the men might be what prevents the stress-induced hormonal changes observed in the women. To establish
a
cold, thermal, cardiovascular and pituitary hormonal responses to cold
Gilberto Cerra, Servizio
Tossicodipendenze USL 4,
changes have been described in animals and humans after exposure to cold environmen¬ tal temperatures. Studies in animals show that cold stress increases the circulating levels of beta-endorphin (1), ACTH (2), cortisol (3) and PRL (4). In humans, increased serum cortisol levels have been described in response to acute cold stress by some authors but not by others (5-7). Furthermore, circulating GH, PRL and beta-endorphin levels have been reported to remain unchanged (5-8) or to decrease after cooling (9-10). The reason for these different findings is unknown; however, differences have been attributed to different experimental conditions, such as room temperature and/or time of exposure to cold. Until now, studies of cold-induced hormonal changes have not taken into account possible differences between the sexes. The separate and comparative study of cold-induced hormo¬ nal changes in men and women may be important in view of the observation that metabolic and thermal responses to cooling are different in the two sexes ( 11 ). In Various hormonal
Via Guasti S. Cecilia 3, 1-43100 Parma,
Italy
the present study, the effects of 30 min cold exposure at 4°C on the circulating concentrations of beta-endorphin, ACTH, cortisol PRL and GH in normal men and in agematched normal women were evaluated and compared.
Subjects and methods healthy volunteers (8 males and 8 females, aged 19-24) participated in the study after giving their informed consent. All subjects were within 10% of their ideal body weight; physical training, ethanol and cigar¬ ette smoking were not allowed in the 48 h leading up to Sixteen
the test.
None of the
subjects
was
affected
by endocrine-
metabolic, heart, liver, renal or other diseases. Psychia¬ tric evaluation for depressive or other major affective
disorders with the Minnesota Multiphasic Personality Inventory (MMPI of Hathaway and McKinley) was negative. Subjects had not taken any drugs during the month prior to testing. The women were eumenorrheic; -
Sex-dependent pituitary hormonal response
acta endocrinologica 1992. 126
they
were
menstrual
studied
cycle.
on
Each
the seventh day of a normal subject was tested individually.
Table 1. Clinical
(mean±SD).
findings in men
and
women
to cold exposure
before and after cold test
Males
Experimental test After
overnight fast and rest in bed, the subject was given a light breakfast at 07.00 and at 09.00, clothed in
Before cold
an
shorts, was seated on a chair in a room at an ambient temperature of 25°C after the insertion of an intra¬
Pulse rate DiastolicBP
venous
Skin
cannula into a forearm vein. A blood sample was taken after 30 min (09.30). The subject was then taken to a room at a temperature of 4°C (air velocity less than 0.2 ms~ ' ; humidity 2.4 gm"! ) where s/he remained for a further 30 min. After cold exposure a second blood sample was collected (10.00). This time point was chosen because previous time course studies of the ACTH/corticosterone response to cold stress in rats have shown maximum changes at 30 min (12). Skin temperature, pulse rate, systolic and diastolic blood pressure were measured before and after cold exposure; blood pressure measurements were taken with a mercury sphygmomanometer, using the fifth sound.
Control test One month after the cold test, subjects were submitted to the same experimental procedure once again, except for the room temperatures, which were 2 5°C in both rooms. Blood samples were obtained from the medial cubital vein in chilled, silicone-coated glass tubes and 5 ml blood was transferred to tubes containing ethylenediaminetetracetic acid (70 yl of a 15% solution) and 250 yl Trasylol (aprotinin, 2500 kallicrein inactivating units, Miles Pharmaceutical). Plasma was separated by centrifugation (3000 x g for 10 min) at 4°C and stored at —70° until assayed for beta-endorphin, ACTH, GH, PRL and cortisol. Betaendorphin assay was carried out using an IRMA method (Nichols S. Juan Capistrano, USA) with a sensitivity of 2.5 pmol/1. Plasma ACTH was measured using an IRMA kit (from the Nichols Institute) with a sensitivity of 3.3 pmol/1. GH, PRL and cortisol were measured utilizing commercial RIA kits (Boehringer, Mannheim) with a sensitivity of 2 yg/l, 1 yg/l and 27.5 nmol/l, respectively. Inter and intra-assay variation coefficients were 6% and 10% for ACTH, 7% and 10% for beta-endorphin, 4% and 7% for prolactin, 3% and 7% for GH and 3.7% and 7.5% for cortisol. The statistical evaluation of data, by repeatedly measuring analysis of variance, was made using the general linear models (GLM) procedure of the SAS Institute Inc. (Cary, NC) statistical package and the Spearman's r linear coefficient correlation, as appro¬
priate.
Results The
mean
skin temperature of all
subjects dropped after
Females
After cold
Before cold
After cold
80±5 72±6 112±7
73 ±8 85±10 129±4
82±6 68±7 100±5
36.7±0.58
35.4±0.10
36.9±0.39 34.9±0.15
Systolic BP temperature
25
79±6 70±10 106±8
30 min in the cold room (p
Gerra G, Volpi R, Delsignore R, Maninetti L, Caccavari R, Vourna S, Maestri D, Chiodera P, Ugolotti G, Coiro V. Sex-related responses of beta-endorphin, ACTH, GH and PRL to cold exposure in humans. Acta Endocrinol 1992;126:24-8. ISSN 0001-5598
possible different
reaction between the male and the female to short-term exposure to stress were measured in eight normal men and eight women (ages 19\p=n-\24).The women were eumenorrheic and were tested in the follicular phase. Each subject, lightly clad, was required to remain for 30 min in a room at an ambient temperature of 2 5\s=deg\Cfollowed by a 30 min period in a cold room at 4\s=deg\C.A month later, control tests were carried out at a constant 25\s=deg\Ctemperature for 1 h in the same subjects. Skin temperature, heart rate, blood pressure and plasma levels of beta-endorphin, ACTH, cortisol, GH and PRL were measured before and after cold exposure in the two groups. Before the test, all examined parameters were similar in the two groups. During cooling, blood pressure rose and pulse rate decreased significantly in the men, but not in the women, whereas skin temperature dropped in both groups. However, after cold exposure skin temperature was significantly lower in the women than in the men. A slight, but not significant increase in beta-endorphin, ACTH, cortisol and GH levels was observed after cooling in the men, whereas the women showed significant increments of these hormones, When values of skin temperature were combined with the differential (after minus before cold test) hormonal values, significant negative correlations were found for beta-endorphin, ACTH, cortisol and GH. As observed by other authors, a significant and peculiar cold-induced decline in plasma PRL levels was observed in the men; by contrast, a slight, but not significant decrement of PRL was found in the women. Control tests at a constant 25\s=deg\Ctemperature did not show significant thermal, cardiovascular or hormonal changes in any subject. These data reflect stronger thermal, cardiovascular and PRL responses to cooling in men than in women. On the other hand, the women, but not the men, showed significant cold-stress\x=req-\ induced increments of beta-endorphin, ACTH and GH, suggesting that the more efficient adaptation to cold of the men might be what prevents the stress-induced hormonal changes observed in the women. To establish
a
cold, thermal, cardiovascular and pituitary hormonal responses to cold
Gilberto Cerra, Servizio
Tossicodipendenze USL 4,
changes have been described in animals and humans after exposure to cold environmen¬ tal temperatures. Studies in animals show that cold stress increases the circulating levels of beta-endorphin (1), ACTH (2), cortisol (3) and PRL (4). In humans, increased serum cortisol levels have been described in response to acute cold stress by some authors but not by others (5-7). Furthermore, circulating GH, PRL and beta-endorphin levels have been reported to remain unchanged (5-8) or to decrease after cooling (9-10). The reason for these different findings is unknown; however, differences have been attributed to different experimental conditions, such as room temperature and/or time of exposure to cold. Until now, studies of cold-induced hormonal changes have not taken into account possible differences between the sexes. The separate and comparative study of cold-induced hormo¬ nal changes in men and women may be important in view of the observation that metabolic and thermal responses to cooling are different in the two sexes ( 11 ). In Various hormonal
Via Guasti S. Cecilia 3, 1-43100 Parma,
Italy
the present study, the effects of 30 min cold exposure at 4°C on the circulating concentrations of beta-endorphin, ACTH, cortisol PRL and GH in normal men and in agematched normal women were evaluated and compared.
Subjects and methods healthy volunteers (8 males and 8 females, aged 19-24) participated in the study after giving their informed consent. All subjects were within 10% of their ideal body weight; physical training, ethanol and cigar¬ ette smoking were not allowed in the 48 h leading up to Sixteen
the test.
None of the
subjects
was
affected
by endocrine-
metabolic, heart, liver, renal or other diseases. Psychia¬ tric evaluation for depressive or other major affective
disorders with the Minnesota Multiphasic Personality Inventory (MMPI of Hathaway and McKinley) was negative. Subjects had not taken any drugs during the month prior to testing. The women were eumenorrheic; -
Sex-dependent pituitary hormonal response
acta endocrinologica 1992. 126
they
were
menstrual
studied
cycle.
on
Each
the seventh day of a normal subject was tested individually.
Table 1. Clinical
(mean±SD).
findings in men
and
women
to cold exposure
before and after cold test
Males
Experimental test After
overnight fast and rest in bed, the subject was given a light breakfast at 07.00 and at 09.00, clothed in
Before cold
an
shorts, was seated on a chair in a room at an ambient temperature of 25°C after the insertion of an intra¬
Pulse rate DiastolicBP
venous
Skin
cannula into a forearm vein. A blood sample was taken after 30 min (09.30). The subject was then taken to a room at a temperature of 4°C (air velocity less than 0.2 ms~ ' ; humidity 2.4 gm"! ) where s/he remained for a further 30 min. After cold exposure a second blood sample was collected (10.00). This time point was chosen because previous time course studies of the ACTH/corticosterone response to cold stress in rats have shown maximum changes at 30 min (12). Skin temperature, pulse rate, systolic and diastolic blood pressure were measured before and after cold exposure; blood pressure measurements were taken with a mercury sphygmomanometer, using the fifth sound.
Control test One month after the cold test, subjects were submitted to the same experimental procedure once again, except for the room temperatures, which were 2 5°C in both rooms. Blood samples were obtained from the medial cubital vein in chilled, silicone-coated glass tubes and 5 ml blood was transferred to tubes containing ethylenediaminetetracetic acid (70 yl of a 15% solution) and 250 yl Trasylol (aprotinin, 2500 kallicrein inactivating units, Miles Pharmaceutical). Plasma was separated by centrifugation (3000 x g for 10 min) at 4°C and stored at —70° until assayed for beta-endorphin, ACTH, GH, PRL and cortisol. Betaendorphin assay was carried out using an IRMA method (Nichols S. Juan Capistrano, USA) with a sensitivity of 2.5 pmol/1. Plasma ACTH was measured using an IRMA kit (from the Nichols Institute) with a sensitivity of 3.3 pmol/1. GH, PRL and cortisol were measured utilizing commercial RIA kits (Boehringer, Mannheim) with a sensitivity of 2 yg/l, 1 yg/l and 27.5 nmol/l, respectively. Inter and intra-assay variation coefficients were 6% and 10% for ACTH, 7% and 10% for beta-endorphin, 4% and 7% for prolactin, 3% and 7% for GH and 3.7% and 7.5% for cortisol. The statistical evaluation of data, by repeatedly measuring analysis of variance, was made using the general linear models (GLM) procedure of the SAS Institute Inc. (Cary, NC) statistical package and the Spearman's r linear coefficient correlation, as appro¬
priate.
Results The
mean
skin temperature of all
subjects dropped after
Females
After cold
Before cold
After cold
80±5 72±6 112±7
73 ±8 85±10 129±4
82±6 68±7 100±5
36.7±0.58
35.4±0.10
36.9±0.39 34.9±0.15
Systolic BP temperature
25
79±6 70±10 106±8
30 min in the cold room (p
