alpha-MSH exhibits opioid antagonist-like effects in the brainstem of rats.
Unilateral microinjections of alpha-MSH (0.3, 1.2 and 12 pmol) into the nucleus tractus solitarius (NTS) of urethane-anaesthetized rats did not modify blood pressure or heart rate (HR). Using a dual microinjection technique, it has been shown that prior injection of alpha-MSH (0.3 pmol) attenuated the pressor effect of a similar injection of dynorphin 1-9 (18 pmol) but did not modify the cardiovascular effects of [Met]enkephalin (14 pmol). Since alpha-MSH has been localized in the NTS, the results indicate that this peptide may play a role in central cardiovascular control, possibly acting in an antagonistic manner to the endogenous opioid peptides.
Carter
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DA
Medical Unit, Charing Cross and Westminster Medical School, Westminster Hospital, London, England.
Lightman
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SL
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009292:Narcotic Antagonists / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D000521:alpha-MSH / Q000494:pharmacology*
D009292:Narcotic Antagonists; D000521:alpha-MSH