EFFECT OF THE PHOTOPERIOD IN MODULATING THE ANDROGENIC CONTROL OF 1-ALKYL-2,3-DIACYLGLYCEROL COMPOSITION IN THE HARDERIAN-GLAND OF THE GOLDEN-HAMSTER, MESOCRICETUS-AURATUS

The golden hamster Harderian gland produces a lipid secretion consisti ng mainly of 1-alkyl-2,3-diacylglycerol. We investigated the compositi on of alkyl and acyl groups in male and female hamster Harderian alkyl diacylglycerol, in animals kept in long and short photoperiods. Female hamsters in long days have alkyl groups with long saturated straight chains (C18:0 and C20:0) and methyl-branched chains (even and odd chai n length iso-branched and odd chain length anteiso-branched chains). A cyl groups in females in long days are mostly long straight chains (C1 6:0) and methyl-branched chains. In females, short photoperiods led to reductions in the proportions of methyl-branched chains and changes i n the proportions of straight chain alkyl and acyl groups; these chang es were prevented by pinealectomy. Male hamsters with intact gonads, m aintained in long days, had no methyl-branched chain alkyl or acyl gro ups; saturated straight chains were generally shorter than those of fe males and the odd chain length saturated C15:0 acyl group was common. Short photoperiods did not significantly alter the composition of male alkyldiacylglycerol. Castrated male hamsters in long days showed a di stinctively female phenotype, with long straight chains and methyl-bra nched alkyl and acyl groups. Castrated males in short days showed a mi xture of male and female characteristics: shorter straight chain alkyl and acyl groups, a total absence of methyl-branched alkyl groups, and the presence of methyl-branched acyl groups. These results and those of other studies suggest that testosterone controls the enzymes isoval eryl acyl-CoA dehydrogenase and 2-methyl branched-chain acyl-CoA dehyd rogenase; in the absence of these enzymes, the primers for the synthes is of methyl-branched chain fatty acids are produced. Our results indi cate that this control is modulated by short photoperiods (perhaps due to reduced prolactin levels). It is also suggested that characteristi cs of male-type alkyldiacylglycerol are better adapted to conditions o f autumn and winter than are those of female-type alkyldiacylglycerol. (C) 1997 Wiley-Liss, Inc.