Morphine-induced potentiation in the dentate gyrus of the hippocampus involves norepinephrine.
We examined the role of norepinephrine in the morphine-induced potentiation in the dentate gyrus of the hippocampus in chronically implanted freely moving rats. The population spikes of the field potentials in the dentate gyrus following perforant path stimulation were recorded before and after morphine injection. We found that a single dose of morphine sulfate (5 mg/kg, i.v.) resulted in a long-lasting augmentation in the amplitudes of population spikes. When pretreated with propranolol (5 mg/kg, i.v.), a beta-adrenoceptor antagonist, the morphine-induced potentiation was significantly attenuated. These results suggested that an increase in norepinephrine release in the hippocampus contributed to the morphine-induced potentiation.
Zhu
Hong
H
Department of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA. hoxhu@ent.umsmed.edu
Zhou
Wu
W
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D018891:Dentate Gyrus / Q000187:drug effects* / Q000502:physiology; D005071:Evoked Potentials / Q000187:drug effects; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009638:Norepinephrine / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000319:Adrenergic beta-Antagonists; D000701:Analgesics, Opioid; D009020:Morphine; D011433:Propranolol; D009638:Norepinephrine