Unit responses in the caudate nucleus to cumulative doses of morphine in unanesthetized, phenobarbital-treated rats.
The effects of cumulative i.v. doses of morphine (1 to 30 mg/kg) on the spontaneous activity of single caudate nucleus neurons were evaluated in rats administered subsurgical doses of phenobarbital. At least 1 week prior to the experiment the animals were prepared with a chronic cranial implant which allowed subsequent restraint as well as the location and recording of neuronal activity with microelectrodes. The rats were pretreated with 40 or 140 mg/kg (i.p.) phenobarbital prior to each experiment. In both phenobarbital treatment groups, 50 to 61% of the neurons tested showed no specific morphine effect. The remainder of the neurons tested in each treatment group responded with morphine-specific increases or decreases in spontaneous activity. It is concluded that a lighter level of anesthesia permits a more dynamic range of caudate neuron responses to morphine.
D000818:Animals; D002421:Caudate Nucleus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D010634:Phenobarbital / Q000008:administration & dosage; D051381:Rats; D011919:Rats, Inbred Strains
D009020:Morphine; D010634:Phenobarbital