Inhibitory effects of centrally administered /ASU1-7/eel calcitonin on basal and stimulated prolactin release in rats.
We investigated the effects of /ASU1-7/eel calcitonin (ASU1-7eelCT) on basal and stimulated prolactin (PRL) release in male rats. /ASU1-7/eelCT was administered intracerebroventricularly (icv) into freely moving rats with indwelling catheters. The administration of /ASU1-7/eelCT (2.5 micrograms/rat, icv) significantly inhibited basal PRL secretion. When PRL secretion was stimulated by exposing rats to restraint stress, /ASU1-7/eelCT (250 ng; 800 ng; 2.5 micrograms/rat, icv) dose-relatedly inhibited the PRL surges at 10 min after stress. The same doses of icv /ASU1-7/eelCT were effective in inhibiting morphine (6 mg/kg, intracarotid, ia-induced PRL release. No effect on stress-induced PRL secretion was observed when the peptide was administered intracarotid at the dose of 10 micrograms/rat. These results demonstrate that /ASU1-7/eelCT, as we previously observed with salmon calcitonin (sCT), has central inhibitory activity on PRL secretion, probably through enhancement of hypothalamic inhibitory pathways involved in the control of PRL.
Sibilia
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V
Dipartimento di Farmacologia, Chemioterapia e Tossicologia Medica, Università di Milano, Italy.
Netti
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C
Guidobono
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F
Villa
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I
Pecile
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A
D000704:Analysis of Variance; D000818:Animals; D002116:Calcitonin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007269:Injections, Intra-Arterial; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000378:metabolism
D009020:Morphine; D011388:Prolactin; D002116:Calcitonin; C012755:elcatonin