Acute female hypogonadism alters adipose tissue fatty acid storage factors and chylomicronemia

Context: Chronic sex steroid deficiency has effects on adipose fatty acid (FA) storage mechanisms and fat oxidation, but the chronology of events are not well understood. Objective: The objective of the study was to examine the acute effects of female sex steroid suppression on cellular mechanisms affecting abdominal and femoral subcutaneous adipose tissue FA storage. Design: This study had a randomized, longitudinal, parallel study design. Setting: The study was conducted at the Mayo Clinic Clinical Research Unit. Participants: Thirty-eight nonsmoking premenopausal women aged 18-50 years participated in the study. Intervention: The intervention included randomization to receive one of the following: 1) no treatment (control), 2) 3.75 mg of Lupron, or 3) 3.75 mg of Lupron and estrogen, but not progesterone, replacement for 49 days, resulting in at least 4 weeks of sex steroid suppression. Main Outcome Measures: Body composition, fat cell size, postprandial chylomicron and nonchylomicron triglyceride concentrations, adipose tissue meal FA storage, direct free fatty acid storage, lipoprotein lipase, acyl CoA synthetase, and diacylglycerol acyltransferase activities, and CD36 content were measured. Results: Compared with the control group, the fed state femoral lipoprotein lipase activity was reduced in women taking Lupron and those taking Lupron and estrogen replacement. In addition, we observed significantly greater postprandial chylomicronemia in the Lupron group than in the other two groups. There were no differences in overall fat storage and oxidation. Depending on the mode of data expression (per unit lipid vs per 1000 adipocytes), there were modest changes in acyl CoA synthetase, diacylglycerol acyltransferase, and CD36 in response to acute sex hormone suppression. Conclusions: Our results suggest estrogen and progesterone may have different effects on the regulation of FA metabolism and that acute sex steroid deficiency in women does not alter fat storage and oxidation.