Morphine produces release of substance P-like immunoreactivity from guinea-pig central nervous system.
Recent evidence suggests that opioids might have excitatory as well as inhibitory actions on neurones. Since substance P (SP) has been implicated in opioid withdrawal, the present experiment was conducted to determine whether SP was released by morphine or morphine withdrawal. Sagittal brain slices and a 2 cm piece of ileum from 5 guinea-pigs were placed in Krebs solution. Morphine 1 microM, produced significant release of SP-like immunoreactivity (SP-LI) within 2 min from brain slices but release from ileum preparations was variable. Naloxone 1 microM, added 5 min after morphine, did not produce significantly greater increase in concentration of SP-LI. It is concluded that morphine releases SP from guinea-pig brain slices.
Chahl
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Neuropharmacology Laboratory, Faculty of Medicine, University of Newcastle, N.S.W., Australia.
D000818:Animals; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D011863:Radioimmunoassay; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism; D013373:Substance P / Q000276:immunology / Q000378:metabolism*; D013375:Substance Withdrawal Syndrome / Q000378:metabolism
D011957:Receptors, Opioid; D013373:Substance P; D009270:Naloxone; D009020:Morphine