Beta-endorphin response to oral glucose tolerance test in obese and non-obese pre- and postmenopausal women.
Beta-endorphin (beta-EP) is a neuropeptide involved in several brain functions, regulating the reproductive axis and behavioral changes. Estrogens play a modulatory role on circulating levels of beta-EP in women. Previous clinical studies have demonstrated high plasma beta-EP levels in obese subjects and increased beta-EP release after an oral glucose tolerance test (OGTT) in normal or obese women. The aim of the present study was to evaluate plasma beta-endorphin levels in response to an OGTT in pre- and postmenopausal obese and non-obese women, in order to investigate if the decrease in gonadal steroid levels at menopause could modify in a different manner the control of beta-endorphin release in response to glucose administration. A group of 24 normal women (age range 45-55 years) were included in the study. The patients were subdivided in four groups of six subjects each: group A, premenopausal women with body mass index (BMI) < 25 (control); group B, premenopausal women with BMI > 25 (obese); group C, post-menopausal women with BMI < 25 (control); group D, postmenopausal women with BMI > 25 (obese). All women were studied between 8.30 and 9.00 am, after overnight fasting, and underwent an OGTT. In obese premenopausal women, basal plasma beta-EP levels were significantly higher than in non-obese women (p < 0.01). In postmenopausal women, regardless of body weight, low basal plasma beta-EP levels were found. A significant increase in plasma beta-EP levels, at 30 and 60 minutes after oral glucose ingestion, was shown in control premenopausal women. No significant modifications to OGTT were shown in plasma beta-EP levels in the other three groups of women. In conclusion, while in premenopausal women the response of plasma beta-EP levels to OGTT is maintained, in postmenopause there is a lack of response to OGTT. This suggests that beta-EP release is dependent upon gonadal steroids, while it is only in part influenced by body weight.
Stomati
M
M
Department of Obstetrics and Gynecology, University of Pisa, Italy.
Bersi
C
C
Bernardi
F
F
Rubino
S
S
Nappi
L
L
Catarsi
S
S
Ferrari
A
A
Spinetti
A
A
Cionini
R
R
Petraglia
F
F
Genazzani
A R
AR
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D017698:Postmenopause / Q000378:metabolism* / Q000502:physiology; D017697:Premenopause / Q000378:metabolism* / Q000502:physiology; D011863:Radioimmunoassay; D001615:beta-Endorphin / Q000097:blood / Q000378:metabolism*
D001786:Blood Glucose; D007328:Insulin; D001615:beta-Endorphin