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alpha-MSH effects on novelty-induced defecation, plasma 11-OHCS and whole brain catecholamines in hypophysectomized
Abstract:
The effect of hypophysectomy on novelty-induced defecation was found to be inhibitory in nature, but this effect was reversed by treatment with alpha-MSH. MSH-treated hypox rats maintained, over days, novelty-induced defecation and showed a significant elevation in plasma 11-OHCS levels, compared with the levels of control-injected counterparts. MSH treatment also reduced over Days 1 to 5 the whole brain DA and whole brain NE levels in hypox animals. Control-treated hypox rats, however, showed an increase in brain NE concentration which was significantly reduced by MSH treatment. Sham-hypox animals also sustained novelty-induced defecation after MSH treatment but did not show a significant rise in plasma 11-OHCS level. Whole brain DA and whole brain NE levels in sham-hypox rats were also reduced significantly by MSH treatment. The behavioral maintenance of defecation in hypox and sham-hypox rats seem to be concomitant with significant reductions in whole brain catecholamines.