Prostaglandin E2 (PGE2) (5 μg in 5 μl) injected into the third ventricle (3rd V) of intact or castrated conscious male rats markedly increased plasma LH titers 15 and 30 min after its injection. PGE1 injected at a similar dose slightly increased plasma LH in intact but not in orchidectomized rats. A small but significant increase in plasma FSH followed 3rd V injection of both PGE2 and PGE1 in intact but not in castrated rats. PGF1α and PGF2α were completely ineffective in modifying plasma LH or FSH titers in either intact or castrated rats. These results indicate that PGE2 and to a lesser extent PGE1 specifically stimulate gonadotropin release in the male rat, possibly by a direct action on the central nervous system. They also support the hypothesis that PGE2 and perhaps PGE1 play a physiological role in neural control of pituitary gonadotropin release.
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