Regulation of central and peripheral benzodiazepine receptors in progesterone-treated rats

The effects of progesterone treatment to male rats on cortical and hippocampal central benzodiazepine (BZ) receptors and peripheral BZ binding sites (PBS) in kidney, testis and heart were evaluated. Chronic progesterone treatment resulted in a 30% elevation of the density of central BZ receptors in cerebral cortex accompanied by a 24% augmentation of PBS in the kidney. No significant change in the density of central BZ receptors in the hippocampus or of PBS in the testis or heart was observed. No change in the affinity of [³H]flunitrazepam and [³H]PK 11195 binding to central BZ receptors and PBS, respectively, was observed. The increase in PBS in the kidney might be associated with the natriuretic effect of this hormone and the adaptatory increase in aldosterone secretion. The up-regulatory effect of progesterone on cortical central BZ receptors may be involved in the neurobehavioral activities of progesterone.