SERUM LEPTIN CONCENTRATIONS IN RESPONSE TO EXERCISE IN POSTMENOPAUSAL WOMEN1598

Abstract

Leptin is a hormone produced in adipose tissue. We and others have found a significant relationship between leptin concentrations and body composition. There is evidence that exogenous leptin will reduce body fat via reduced caloric intake and increased metabolic activity in wild type and obese mice, which lack a functional leptin gene. We have examined a group of postmenopausal women to study the effects of exercise on a variety of anterior pituitary and adrenal hormones. We have also examined the effects of exercise on serum leptin concentrations in this same group of subjects. Seven healthy, postmenopausal (natural and surgical) women (5 on estrogen replacement, ERT, 2 off), mean (±SE) age 53.0 ± 3.35 y, completed 30 minutes of treadmill exercise (after an overnight fast) at 79.0 ± 0.83% of VO2max Commencing at 0830h, pre- (-), mid- (+), and postexercise (R) blood samples were collected from an intravenous catheter at -30, 0, +15, R0, R10, R20, R35, R50, R65, and R80 min, respectively. A control session conducted a month later, consisted of the same blood sampling protocol without exercise. Our data from another ongoing study suggested that ERT does not affect the relationship between leptin levels and body composition, therefore we included ERT and non-ERT women in the same group. Lactate peaked at 5.53± 1.02 mmol/L (+15). Baseline leptin concentrations of 21.96 ± 7.74 ng·ml-1 did not change significantly over the course of the exercise session. There was no significant difference between the area-under-the-curve (AUC) leptin concentrations for the exercise (-298.80± 138.44 ng·min·ml-1) and control (-201.35± 100.58 ng·min·ml-1) trials, respectively. Data suggest that leptin concentrations in postmenopausal women are not altered under these exercise conditions.