The antinociceptive and hypothermic effects of intracisternal administration of 11 endogenous neuropeptides and morphine were evaluated in mice. Of the substances tested, only neurotensin (NT) and β-endorphin exerted significant antinociceptive and hypothermic effects; NT was the most potent antinociceptive agent via this route of administration. . Both NT and β-endorphin were, on a molar basis, considerably more potent antinociceptive agents than morphine, [Met]enkephalin, or [Leu]enkephalin. NT-induced analgesia and hypothermia both were significantly dose-dependent. Substance P was found to produce significant hyperalgesia and hyperthermia. Bombesin produced a significant hypothermic effect, whereas somatostatin and luteinizing hormone-releasing hormone (luliberin) produced hyperthermia. None of the other peptides studied [bradykinin, thyrotropin-releasing factor (thyroliberin), melanocyte-stimulating hormone release-inhibiting factor (melanostatin), somatostatin, [Met]enkephalin, and [Leu]enkephalin] produced any significant alterations in colonic temperature or response to a noxious stimulus with the doses tested. These data demonstrate that NT and β-endorphin, two endogenous brain peptides, are potent in inducing hypothermia and in producing an antinociceptive state.
|Original language||English (US)|
|Number of pages||4|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Dec 1 1979|
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