Progesterone-dependent sexual behavior and protein patterns in the ventromedial hypothalamus of the adult female rat

摘要

Controversy exists concerning mechanisms by which progesterone exerts central nervous system effects on behavior. Progesterone may affect behavior by genomic regulation of protein synthesis. Alternatively, it may work through non-genomic mechanisms, consistent with its short latency to act. Recent work suggests that progesterone may elicit its effects on sexual behavior by more than one mechanism in a tissue specific manner. In the present study, we have examined whether progesterone facilitation of sexual behavior is correlated with modification of protein synthesis patterns in the ventromedial hypothalamus (VMH). Ovariectomized rats were divided into three groups: estradiol (4 ug/ka at 0 and 18 hrs), estradiol (at 0 and 18 hrs) plus progesterone (2 mg/kg at 37 hrs), and vehicle only. (sup 35)S-labeled cysteine and methionine were bilaterally infused into the VMH at 37 hrs (the time of progesterone administration). Following 4 hrs of infusion, animals were tested for sexual behavior and sacrificed. Newly synthesized VMH proteins were separated by two dimensional gel electrophoresis followed by fluorography. Analysis of approximately 660 spots/fluorogram in two independent replications indicated that no protein was completely induced or lost as a result of being treated with progesterone. The abundances of several proteins were significantly altered in response to progesterone treatment in each replication; however, none were changed in abundance in both replications. These findings present no evidence that progesterone causes detectable alterations in VIMH protein patterns between 10-100 kDa in the 4.8-6.7 apparent pI range.