An extract of cannabis (5 and 15 mg/kg expressed as delta 9-THC) orally administered to rats caused an elevation of the nociceptive threshold (tail-flick latency and vocalization tests). Naloxone and naltrexone (blockers of mu-type opiate receptors) as well as MR 1452 (blocker of kappa opiate receptors) did not prevent the antinociceptive effect of cannabis… (More)
We determined the effects on nociceptive threshold and motor function of dynorphin-gene products, dynorphin A-(1-32) (DYN A-(1-32), DYN A-(1-8), DYN B and DYN B-29 and the non-opioid peptides somatostatin, neurotensin and salmon calcitonin (s-CT) after intrathecal administration in the rat. DYN A-(1-32) (25 nmol) produced maximal elevation of tail-flick… (More)
Salmon calcitonin injected intrathecally in unanesthetized rats produced long-lasting, dose-dependent elevations of nociceptive threshold as measured in the hot plate test. This antinociceptive action was nonopiate in nature as it was uninfluenced by the narcotic antagonists naloxone and MR 1452; moreover, the peptide was still able to raise the nociceptive… (More)
Immunoreactive dynorphin A (ir-Dyn A) was detected throughout the human gastrointestinal tract by a validated radioimmunoassay. Moreover, the stability of 125I-Dyn A during extraction procedures was confirmed by high performance liquid chromatography. Levels of ir-Dyn A were higher in the stomach and in the small bowel. In tissue samples separated into the… (More)
The intracerebroventricular (i.c.v.) administration of pertussis toxin (0.5 microgram) to rats significantly reduced the hypothermic and behavioural effects (episodic bizarre postures characterized by limb rigidity and followed by barrel rolling) induced by i.c.v. dynorphin A (10 micrograms). These central effects of dynorphin A thus appear to be initiated… (More)
Prodynorphin-derived peptides were tested for their effects on body temperature after intracerebroventricular administration to unrestrained male rats. Dynorphin A (Dyn A) (5 and 10 nmol) and Dynorphin A-(1-32) (Dyn A-(1-32) (2.5 and 5 nmol) lowered body temperature with a maximum approximately 30 min after administration. Dyn B (up to 50 nmol) did not… (More)
The antagonism of the antinociceptive effects of various kappa-opioid agonists has been studied in the mouse abdominal constriction test. Naloxone produced a much smaller degree of antagonism of U50488H than it did of two other kappa-agonists, U69593 and tifluadom. The kappa-selective antagonist, norbinaltorphimine, also failed to shift the dose-response… (More)
Selective radiofrequency and neurotoxic lesions of the serotonergic pathways caused in the rat a significant reduction of ir-dynorphin A and B in the hypothalamus but not at pituitary level. These data confirm that dynorphin-related peptides are regulated independently in these areas.