Suppressive effect of dynorphin-(1-13) on luteinizing hormone release in conscious castrated rats

The effect of intraventricular administration of dynorphin-(1-13) on luteinizing hormone (LH) release was studied in castrated conscious rats. The administration of 5 micrograms of dynorphin-(1-13) into the lateral ventricle inhibited LH secretion. Intravenous administration of naloxone blocked this suppressive effect of dynorphin on LH release. These results suggest a possible role of dynorphin, in addition to beta-endorphin and Met5-enkephalin, in the control of LH release in male rats.