The effects of hypophysectomy and testosterone treatment on the composition and metabolism of testicular lipids.

The effects of hypophysectomy and of testosterone administration on lipid composition and metabolism of rat testicular tissue have been investigated. Increased concentrations of triacylglycerols and cholesterol were observed in testes of hypophysectomized compared to control (non-hypophysectomized) rats on the eighth day posthypophysectomy. Administration of testosterone maintained the concentrations of these lipids at about normal levels. The concentration of phospholipids was not affected by the hypophysectomy. Incorporation of 14C from 1-[14C] linoleate into testicular lipids was determined 24 hours after intratesticular injection. In hypophysectomized compared to control rats there was more 14C in C 16:0, C 20:2 and C 20:3 and less 14C in C 20:4 and C 22:4 of both phospholipids and triacylglycerols. After intratesticular injection of 1-[14C] eicosatrienoate there was more 14C in C 16:0 and C 20:3 and less 14C in C 20:4 and C 22:4 of both phospholipids and triacylglycerols of hypophysectomized compared to control rats. Intratesticular injection of 1-[14C]-arachidonate resulted in less 14C incorporation in C 22:4 in testes of hypophysectomized than in those of control rats. Treatment with testosterone did not affect the metabolism of any of the 14C-substrates. These results indicate that the testicular desaturation of C 20:3 to arachidonate, requiring a delta 5 desaturase, is inhibited by hypophysectomy and that testosterone by itself may control the concentrations of some testicular lipid classes but not the metabolism of the polyenoic acids.