Evidence for the involvement of protein kinase C in the modulation of morphine-induced 'analgesia' and the inhibitory effects of exposure to 60-Hz magnetic fields in the snail, Cepaea nemoralis.
There is substantial evidence that magnetic fields can reduce opiate-induced analgesia, with alterations in calcium channel function and/or calcium ion flux being implicated in the mediation of these inhibitory effects. The present experiments were designed to examine the effects of protein kinase C (PKC), a calcium/diacylglycerol/phospholipid-dependent protein kinase, on opiate-induced analgesia and its involvement in mediating the inhibitory effects of exposure to magnetic fields. We observed that morphine-induced antinociception, or 'analgesia', in the land snail, Cepaea nemoralis, as measured by the enhanced latency of response to a thermal (38.5 degrees C) stimulus, was reduced in dose-related manner by the PKC activator, SC-9. Exposure of snails for 2 h to a low intensity (1.0 gauss rms) 60-Hz magnetic field also reduced morphine-induced analgesia. The inhibitory effects of the 60-Hz magnetic field on morphine-induced analgesia were significantly reduced by the PKC inhibitors, H-7 and H-9, and significantly enhanced by the PKC activator, SC-9. The non-specific protein kinase inhibitor, HA-1004, and the preferential calmodulin inhibitor, W-7, had no significant effects on either morphine-induced analgesia or the inhibitory actions of exposure to the magnetic fields. These results suggest that: (1) PKC has antagonistic effects on opiate-mediated analgesia in the snail, Cepaea, and (2) that the inhibitory effects of magnetic fields on opiate-induced analgesia involve alterations in PKC.
Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
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Kavaliers
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Ossenkopp
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Tysdale
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000698:Analgesia; D000818:Animals; D004789:Enzyme Activation; D006358:Hot Temperature; D007546:Isoquinolines / Q000494:pharmacology; D008280:Magnetics; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012908:Snails / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology*
D007546:Isoquinolines; D010879:Piperazines; D013449:Sulfonamides; C049999:N-(6-phenylhexyl)-5-chloro-1-naphthalenesulfonamide; D009270:Naloxone; D009020:Morphine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; D011493:Protein Kinase C