Lipolytic Effects of Testosterone Hormone Replacement Therapy in A Rat Model of Andropause Versus Normal Controls

Abstract
Background: Testosterone (T) actions extend beyond the reproductive functions to include diverse metabolic pathways. Lipolytic effect of T is still underinvestigated, especially regarding the involved enzymes.
Aim of Study: This work measures two key lipolysis-enzymes in both normal and orchiectomized rats with/without T administration.
Material and Methods: Forty rats (200-300g) were sub-divided into 4 equal groups (n=10/group); (A) Group I: Sham-operated control group. (B) Group II: Sham-operated rats were injected with IM testosterone undecanoate (100mg/kg, for two weeks). (C) Group III: Andropause model was done by orchiectomy, (D) Group IV: Testosterone-replacement therapy in orchiectomized rats. T, Hormone-Sensitive Lipase (HSL), Adipocyte Triglyceride Lipase (ATGL), Free Fatty Acids (FFA), and lipid profile were measured using the commercially available ELISA kits. Food intake was measured manually in addition to body weight changes before during and after treatment. ANOVA with LSD post hoc test and Pearson correlation were used for analysis.
Results: The castrated rats showed lower food intake, lower body weight, and lower weight gain. Regarding adipose tissue lipolytic enzymes, ATGL was significantly decreased while both HSL and FFA were insignificantly changed. T replacement therapy in castrated rats increased blood products of lipolysis due to an increased level of ATGL, HSL, and FFA, in addition to the significant increase in food intake without significant wt changes. Similar effects were demon-strated in normal rats treated with T.
Conclusion: T hormone therapy increased food intake, without significant changes in weight due to stimulation of lipolysis process mainly via stimulation of ATGL and HSL.