Effects of oestradiol, the oestrous cycle and pregnancy on weight, metabolism and cytosol receptors in the oviduct and vaginal complex of the brushtail possum (Trichosurus vulpecula).

Abstract

Weight, RNA, DNA and protein content of the oviduct, vaginal cul-de-sac, lateral vagina and urogenital sinus and oestradiol and progesterone cytosol receptor concentrations in vaginal cul-de-sac, lateral vagina and urogenital sinus were examined after administration of oestradiol to ovariectomized animals and on days 0, 5, 9 and 13 of the non-pregnant cycle and on day 13 of the pregnant cycle. In ovariectomized animals, oestradiol induced an increase in weight, RNA:DNA and protein:DNA ratios and a decrease in DNA:tissue weight ratio for each organ and in addition an increase in total DNA in vaginal cul-de-sac and urogenital sinus. There was no effect of oestradiol on oestradiol cytosol receptor concentration but there was a significant increase in progesterone cytosol receptor concentration in all organs that were examined. During the oestrous cycle, changes in the wet weight of each organ showed a common pattern with maximum weight at day 0 followed by variable rates of decline until day 13. In oviduct and vaginal cul-de-sac, the decrease in weight was paralleled by a decrease in RNA:DNA and protein:DNA ratios whereas the DNA: tissue weight ratio showed the opposite pattern and total DNA remained unchanged. The changes in the lateral vagina and urogenital sinus were similar except that a significant decline in total DNA was also seen after day 0 and the DNA:tissue weight and protein:DNA ratios in the urogenital sinus and the lateral vagina respectively showed no significant changes. Progesterone cytosol receptor concentration in the lateral vagina and urogenital sinus were high on day 0 and then declined until day 13. In contrast, there were no consistent effects on oestradiol receptor concentration.