Effect of gonadal steroids on hypothalamus and anterior pituitary endo-oligopeptidase B (proline-endopeptidase) activity in castrated female rats |
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Authors: | P López-Jaramillo J Antunes-Rodrigues A C Camargo |
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Affiliation: | 1. Department of Pharmacology, Faculty of Medicine of Ribeirão Preto, University of São Paulo 14100 Ribeirão Preto, SP, Brazil;2. Facultad de Ciencias Médicas, Universidad Central del Ecuador, Quito, Ecuador |
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Abstract: | In the present study we investigated the possible participation of endo-oligopeptidase B (poline-endopeptidase) in the control of gonadotrophin secretion through the control of LH-RH inactivation. This enzyme selectively hydrolyzes the Pro9-Gly10-NH2 peptide bond of LH-RH, thereby inactivating this substance. The enzyme activity was evaluated using a specific colorimetric substrate, i.e., Z-Gly-Pro-SM. Female adult Wistar rats were submitted to castration, experimental situations that are known to produce changes in gonadotrophin secretion. Hypothalamic and pituitary endo-oligopeptidase B activity was shown to be present predominantly in the soluble fraction of the enzyme preparations. The results also indicated that endo-oligopeptidase B activity adult female rat pituitary decreased after castration and increased after administration of estradiol and progesterone to castrated animals. The present results lead us to suggest that anterior pituitary endo-oligopeptidase B may be related to the control gonadotrophin secretion in female rats. |
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Keywords: | Endo-oligopeptidase B LH-RH degrading enzyme Proline-endopeptidase Sexual steroids |
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