The activity of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system in relation to waist/hip circumference ratio in men.
OBJECTIVE
To investigate possible differences, between generally and abdominally obese men, in activity and regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system.


METHODS
Fifty non-diabetic, middle-aged men were selected to obtain two groups with similar body mass index (BMI) but different waist/hip circumference ratio (WHR). Measurements were performed of the activity of the HPA axis and the sympathetic nervous system, as well as metabolic and endocrine variables.


RESULTS
Men with a high WHR, in comparisons with men with a low WHR, had higher insulin, glucose, and triglyceride values in the basal state and higher glucose and insulin after an oral glucose tolerance test. Men with high WHR had elevated diurnal adrenocorticotropic hormone (ACTH) values but similar cortisol values, except lower cortisol values in the morning. Diurnal growth hormone concentrations showed reduced peak size. Stimulation of the HPA axis with corticotropin-releasing hormone (CRH) and laboratory stress showed no difference in ACTH values between groups, but cortisol values were lower in men with high WHR. In comparison with men with a low WHR, men with a high WHR had elevated pulse pressure and heart rate in the basal state and after challenges by CRH and laboratory stress. They also had increased urinary excretion of catecholamine metabolites.


CONCLUSIONS
These results suggest a mild dysregulation of the HPA axis, occurring with elevated WHR independent of the BMI. The results also indicate a central activation of the sympathetic nervous system, such as in the early phases of hypertension, correlating with insulin resistance.
Ljung
T
T
Department of Heart and Lung Diseses, Sahlgrenska University Hospital, Göteburg, Sweden. thomas.ljung@telia.com
Holm
G
G
Friberg
P
P
Andersson
B
B
Bengtsson
B A
BA
Svensson
J
J
Dallman
M
M
McEwen
B
B
Björntorp
P
P
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D001786:Blood Glucose; D001794:Blood Pressure; D001824:Body Constitution / Q000502:physiology*; D002940:Circadian Rhythm; D005951:Glucose Tolerance Test; D006339:Heart Rate; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D010913:Pituitary-Adrenal System / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013997:Time Factors; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D007328:Insulin; D014280:Triglycerides; D000324:Adrenocorticotropic Hormone