title: Calcium channel blockers inhibit the antagonistic effects of Phe-Met-Arg-Phe-amide (FMRFamide) on morphine- and stress-induced analgesia in mice.
abstract: Determinations were made of the effects of the calcium channel blockers, nifedipine and verapamil, on the antagonistic effects of FMRFamide (Phe-Met-Arg-Phe-NH2) and naloxone on morphine- and immobilization-induced opioid analgesia in mice. Intraperitoneal (i.p.) administrations of the calcium channel antagonists significantly reduced the inhibitory effects of intracerebroventricular (i.c.v.) FMRFamide, but had no effects on i.p. or i.c.v. naloxone-mediated inhibition of either morphine- or immobilization-induced analgesia. These results suggest that the antagonistic effects of FMRFamide, (or other endogenous FMRFamide-like peptides) on both opiate- and opioid-mediated analgesia in mice may involve alterations in the functioning of calcium channels.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004347:Drug Interactions; D019835:FMRFamide; D007473:Ion Channels / Q000502:physiology; D051379:Mice; D009020:Morphine / Q000008:administration & dosage* / Q000627:therapeutic use; D009420:Nervous System / Q000503:physiopathology*; D009479:Neuropeptides / Q000008:administration & dosage*; D009543:Nifedipine / Q000008:administration & dosage*; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology*; D013312:Stress, Physiological / Q000503:physiopathology*; D014700:Verapamil / Q000008:administration & dosage*
chemical_list: D007473:Ion Channels; D009479:Neuropeptides; D019835:FMRFamide; D009020:Morphine; D014700:Verapamil; D009543:Nifedipine; D002118:Calcium