The biosynthesis and turnover of different molecular species of rat testicular choline phosphoglycerides and triacylglycerols following intratesticular injection with (1(3)-14C)glycerol.

Rats were sacrificed 1, 4, 8, 24, 48 and 96 h after an intratesticular injection with [1(3)-14-C]glycerol. The choline phosphoglycerides and triacylglycerols were isolated and the choline phosphoglycerides were converted to diacylglycerols by treatment with phospholipase C. These diacylglycerols and the triacylglycerols were fractionated into molecular species using argentation thin-layer chromatography. At early time periods the percent of radioactivity incorporated into the oleate- and linoleate-containing diacylglycerols exceeded the molar contribution of these two fractions. The percent of radioactivity in the linoleate fraction declined rapidly at later time periods while the percent of radioactivity in the oleate fraction also declined but not as rapidly. In contrast the percent of radioactivity in the arachidonate and docosa-4,7,10,13,16-pentaenoate-containing diacylglycerols at early time periods was lower than the molar amounts of these diacylglycerols. At later time periods the percent of radioactivity in these two fractions increased. These findings suggests that oleate- and linoleate-containing choline phosphoglycerides are made largely by total synthesis while a deacylation-acylation pathway plays a major role in the biosynthesis of the highly unsaturated choline phosphoglycerides. The calculated apparent half-lifes for the oleate-, linoleate-, arachidonate- and docosa- 4,7,10,13,16-pentaenoate-containing diacylglycerols were respectively 35, 18, 41 and 46 h. The percent incorporation of [1(3)-14-C]glycerol into the various triacylglycerol fractions did not differ markedly from the molar contribution of the respective molecular fractions suggesting that the various molecular species of rat testicular triacylglycerols are all synthesized and turn over at about the same rate.