Metabolism of glyceryl 1-14C-trilinoleate in rat testis

Animals of the Sprague-Dawley strain were injected intratesticularly with radioactive glyceryl 1-¹⁴C-trilinoleate in a sequential experiment and killed at 1/4, 1/2, 1, 3, 6, 12, 24, 36 and 48 hr. Distribution and concentration (specific activity) of radioactivity among the lipid classes and fatty acids were determined. The results showed that radioactive 1-¹⁴C-linoleic acid was released from the glyceryl trilinoleate and incorporated throghout the lipid classes. The pattern of the distribution of the radioactivity and specific activities showed that the transformation of linoleic acid between the triglyceride, diglyceride and fatty acid pools was an equilibrium process. Linoleic acid released from glyceryl 1-¹⁴C-trilinoleate was converted to higher polyunsaturated fatty acids which were incorporated throughout the lipid classes, and was catabolized as evidenced by the finding of radioactivity in palmitic acid. The main metabolic pools in the interconversion of linoleic acid were arachidonic and 22∶5 acids. Small amounts of 20∶3 and 22∶4 were also detected and had high specific activities indicative of their roles as precursors.