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 nongenomic mechanisms, consistent with its short latency to act. In the present study, we have examined the hypothesis that progesterone facilitation of sexual behavior is correlated with modification of the synthesis of specific proteins in the ventromedial hypothalamus (VMH). Ovariectomized rats were treated with either estradiol (4 μg/kg at 0 and 18 h) or estradiol (at 0 and 18 h) plus progesterone (2 mg/kg at 37 h). 35S-labeled cysteine and methionine were bilaterally infused into the VMH at 37 h (the time of progesterone administration). Following 4 h 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 qualitative or quantitative changes in protein synthesis occurred in response to progesterone. In each replication statistical analysis suggested that the abundance of several proteins may have changed, but no specific proteins were changed in abundance in both replications. Within the range of this technique (10-100 kDa and 4.8-6.7 apparent pI) we found no evidence that progesterone causes alterations in VMH protein synthesis.
ASJC Scopus subject areas
- Molecular Biology
- Cellular and Molecular Neuroscience
- Cell Biology