K. Tsutsui et al., EFFECT OF SEASON AND PHOTOPERIOD ON THE FOLLICLE-STIMULATING-HORMONE RECEPTORS IN A SUBTROPICAL BIRD, Journal of Biosciences, 19(4), 1994, pp. 485-489
Annual changes in and photoperiodic influence oh the weight of gonads,
a parameter of gonadal activity, are much smaller in female birds tha
n in males. Effect of season and photoperiod on the follicle-stimulati
on, hormone receptors in the testis or ovary was studied using a subtr
opical weaver finch. The number of follicle-stimulating hormone bindin
g sites per unit testicular weight showed a peak in the non-breeding p
hase; while the total number of binding sites per two testes was maxim
al in the breeding phase and minimal in the regressive phase. In contr
ast, seasonal changes in follicle-stimulating hormone binding sites in
the ovary were less marked. Exposure to short-day during the breeding
phase induced marked decreases in the numbers of binding sites per un
it testicular weight and per two testes. These numbers markedly increa
sed after transfer to long-day during the non-breeding phase. However,
there was no significant effect of short-day or long-day exposure on
follicle-stimulating hormone binding sites in the ovary. These results
suggest that photoperiod is an effective environmental factor in the
regulation of follicle-stimulating hormone receptors in the testis and
the effect is manifested by pronounced changes in the testicular weig
ht during annual breeding cycle.