Anticipatory hyperexcitability and tolerance to the narcotizing effect of morphine in the rat


    loading  Checking for direct PDF access through Ovid

Abstract

Examined the role of Pavlovian conditioning in tolerance to the narcotizing effect of a high dose of morphine in 32 male albino Sprague-Dawley rats. Initially, 2 groups received 9 injections of morphine (40 mg/kg), and 2 groups received 9 injections of saline. One group administered each substance was injected in 1 of 2 distinctive environments: the animal colony or a distinctive room. Subsequently, Ss in all groups received 5 morphine injections in the distinctive room. Analyses of videotape records of postinjection behavior indicated that Ss tested in the presence of the usual predrug cues were more tolerant to the narcotizing effect of morphine than Ss tested with cues different from those previously associated with morphine. In addition, Ss tested with the usual predrug cues exhibited more anticipatory “hyperexcitable” behavior than Ss tested in the absence of the usual predrug cues. Results provide further evidence that compensatory pharmacological conditional responses partially mediate tolerance and suggest that these drug-anticipatory responses contribute to so-called “withdrawal symptoms.” (18 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

    loading  Loading Related Articles