Inhibitory effect of propranolol on lipid synthesis in gonadectomized malehamster flank organs

Background: This paper describes the inhibitory effect produced by proprano lol pre-treatment on lipid synthesis in flank organs from intact, gonadecto mized, and isoproterenol-treated male hamsters. Furthermore, the effect ind uced by the same treatments on gland sebum composition is reported. Methods: Different groups of male hamsters were injected daily with propran olol, isoproterenol or propranolol plus isoproterenol. Treatment-effect was evaluated determining the in vitro incorporation of radioactive acetate in to lipids in hamster flank organs from intact and castrated animals. Additi onally, radiolabeled lipids were isolated and identified using TLC and auto radiography as methods. Results: Results demonstrate that castration significantly decreases lipid synthesis in male hamster flank organs. In addition, propranolol treatment inhibits such synthesis in glands from intact, gonadectomized, and isoprote renol-treated animals. However, isoproterenol treatment was ineffective whe n compared to intact or gonadectomized control vehicle-treated animals. Lipid classes isolated and identified lipids either in castrated or in drug -treated animals were phospholipids, cholesterol, monoglycerides, fatty aci ds, waxes and cholesterol esters. Conclusions: Results indicate an inhibitory effect induced on lipid synthes is by beta-adrenergic receptor antagonists; however, beta-adrenergic agonis ts drugs do not stimulate it. Data suggest a permissive role of adrenergic hormones on lipid synthesis in intact and in gonadectomized animals. Furthe rmore, castration decreased the synthesis, suggesting that a tight coupling between beta-adrenergic receptors and androgen receptors may be a prerequi site for lipogenesis in this tissue. Pre-treatment does not modify sebum composition in gonadectomized animal gl ands. These data support the evidence that activation of beta-adrenergic re ceptors could be an independent factor in the lipid composition regulation process.