Alterations in Nociception and Body Temperature after Intracisternal Administration of Neurotensin, $\beta $-endorphin, other Endogenous Peptides, and Morphine

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 76; no. 10; pp. 5368 - 5371
• Main Authors: Nemeroff, Charles B., Osbahr, Albert J., Manberg, Paul J., Ervin, Gregory N., Prange, Arthur J.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.10.1979; National Acad Sciences
• Subjects: Administered dose; Analgesics; Animals; Body temperature; Body Temperature - drug effects; Body Temperature Regulation - drug effects; Brain; Dosage; Dose response relationship; Dose-Response Relationship, Drug; Endorphins - pharmacology; Enkephalins - pharmacology; Hormones - pharmacology; Hypothermia; Male; Mice; Morphine; Morphine - pharmacology; Neurobiology; Neurotensin - pharmacology; Pain; Peptides - pharmacology; Structure-Activity Relationship
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.76.10.5368

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 $\beta $-endorphin exerted significant antinociceptive and hypothermic effects; NT was the most potent in inducing hypothermia whereas $\beta $-endorphin was the most potent antinociceptive agent via this route of administration. Both NT and $\beta $-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 $\beta $-endorphin, two endogenous brain peptides, are potent in inducing hypothermia and in producing an antinociceptive state.