Systemic naloxone enhances cerebral blood flow in anesthetized morphine-dependent rats.
Laser-Doppler flowmetry was used to study cerebral cortical blood flow responses to morphine and naloxone in morphine-naive and -dependent rats. The experiments were performed in spontaneously breathing anesthetized rats. Morphine (10 mg/kg, i.p.) administration reduced regional cerebral blood flow in control, sham-operated and morphine-dependent rats, but the depressant effect of morphine in morphine-dependent animals was less than that in control and sham-operated groups. While naloxone (0.5 mg/kg, s.c.) had no considerable effect on regional cerebral blood flow in control and sham-operated groups, it increased regional blood flow in morphine dependent ones. The depressant effect of morphine in all groups and the enhancing effect of naloxone in morphine-dependent animals were not seen after local application of lidocaine at the recording site. This study may provide a framework to study the cellular and molecular mechanisms responsible for coupling neuronal electrical activity with regional alterations in blood flow during precipitation of morphine withdrawal.
Zamani
R
R
Department of Physiology, School of Medical Sciences, Tarbiat Modarres University, P.O. Box 14115-111, Tehran, Iran.
Semnanian
S
S
Fathollahi
Y
Y
Hajizadeh
S
S
D000758:Anesthesia; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000098:blood supply; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D003967:Diarrhea / Q000139:chemically induced; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000009:adverse effects; D009021:Morphine Dependence / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010146:Pain / Q000139:chemically induced; D051381:Rats; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome / Q000473:pathology / Q000503:physiopathology; D015431:Weight Loss / Q000187:drug effects
D000779:Anesthetics, Local; D009292:Narcotic Antagonists; D009270:Naloxone; D009020:Morphine; D008012:Lidocaine