Central nervous system effect of calcitonin: stimulation of prolactin release in rats.
Effect of [Asu 1,7]eel calcitonin (CT) on prolactin (PRL) release was examined in male rats under urethane anesthesia. Intravenous injection of 4-20 micrograms [Asu1,7]eel CT did not modify plasma PRL levels. Injections of 0.5-2.5 micrograms [Asu1,7]eel CT into the lateral ventricle produce a significant and dose-related increase of plasma PRL within 10 min of injection. When intraventricularly injected in an equimolar dose (0.74 nmol/10 microliters), eel CT11-32, eel CT15-32, [Asu1,7]eel CT1-16 and [Asu1,7]eel CT1-9 showed 44.8, 25.7, 19.9 and 10.1% the potencies of [Asu1,7]eel CT, respectively, in stimulating activity of PRL release. The rise of plasma PRL after [Asu1,7]eel CT injection were significantly less or abolished not only in hypothalamic-lesioned rats but also in rats with complete deafferentation. Pretreatment with alpha-methyl-p-tyrosine (250 mg/kg, 12 h before) but not with p-chlorophenylalanine (300 mg/kg, 72 and 24 h before) resulted in a suppression of [Asu1,7]eel CT-induced PRL release. These results suggest the following: first, PRL release is stimulated by centrally injected [Asu1,7]eel CT, the action site of which may exist in the extrahypothalamic area; second, brain catecholamines may be involved in the mechanism of [Asu1,7]eel CT-evoked PRL release; third, the C-terminal portion of the peptide may play an important role in stimulating PRL release.
D000818:Animals; D002116:Calcitonin / Q000494:pharmacology*; D010134:Fenclonine / Q000494:pharmacology; D007031:Hypothalamus / Q000378:metabolism*; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D010446:Peptide Fragments; D019805:alpha-Methyltyrosine; D011388:Prolactin; D002116:Calcitonin; D010134:Fenclonine