Differences in prolyl-leucyl-glycinamide metabolism by hypothalamus, pituitary and cerebral cortex of male and female rats.
l-Prolyl-l-leucyl-glycinamide is rapidly hydrolyzed by hypothalamic, hypophyseal and cortical homogenates from male or female rats. The peptidase activity is higher in the pituitary followed in decreasing order by the hypothalamus and the cerebral cortex. It is mostly localized in the supernatant fraction of a 100,000 g centrifugation and is inhibited by bacitracin. Tissues from female rats are half as active as those from male rats and show variations during the estrous cycle, with very low PLG metabolism at diestrus 1 in pituitary and hypothalamus. In contrast, the cerebral cortex at proestrus and estrus has significant lower hydrolyzing activity than at diestrus. No change of the peptidase activity is observed in tissues from ovariectomized animals after treatment with estrogen or progesterone. The results obtained suggest the existence of a correlation between peptidasic activity and melanotropin secretion.
Celis
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Instituto de Investigación Médica, Mercedes y Martin Ferreyra, 5000 Córdoba, Argentina.
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