Effects of castration and ethanol on amygdaloid substance P immunoreactivity

These studies were designed to determine the effects of castration and ethanol (ETOH) on the relative content of substance P (SP) immunoreactivity in the hypothalamus and the central and medial amygdaloid nuclei (CM-AM). Differences visualized immunocytochemically between saline-treated intact and castrated rats indicated that a visible decrease in the number and intensity of immunostained fibers within the CM-AM occurred following castration. Conversely, the number of labeled fibers and the intensity of the reaction product was greater in castrated rats treated with ETOH as compared to the castrated rats receiving only saline. In ETOH-treated intact animals, the number of SP-containing fibers of the CM-AM was slightly greater than the saline-treated intact controls. Similar results were seen for specific regions of the hypothalamus although they were less pronounced than that visualized in the CM-AM. These data indicate that both castration and administration of ETOH affects hypothalamic and amygdaloid content of SP, and also suggests that ETOH may diminish the release of SP. Possible interactions between SP and luteinizing hormone-releasing hormone are discussed.