PubMed Health⌕ Search

Biomedical subjects

J A Dougherty

Publications and source records attributed to J A Dougherty.

2 recordsLinked to original sources
PubMedDate not supplied

Interoceptive conditioning through repeated suppression of morphine-abstinence. II. Relapse-testing.

The reinforcing properties of etonitazene, both conditioned and unconditioned, were measured in rats that had received saline only by continuous intravenous infusion ("saline" group) and in two groups of rats that had been physically dependent on morphine to equal degrees (and presumably had developed equal degrees of tolerance to morphine): one by once daily passive intravenous injection of morphine ("injection" group) and the other by passive continuous intravenous morphine infusion at the same daily doses for approximately the same number of days ("infusion" group). Prior to passive saline and morphine administration, all rats were trained to press right- and left-sided levers for water reinforcement from 1600 to 0800 hrs to a not more than 60-40 split, and these and other measures ("baselines") were repeated after recovery from the early (acute) morphine-abstinence syndromes. Then etonitazene, 5 micrograms/ml, was substituted for water on the nonpreferred side and all measures were repeated from 1600 to 0800 hrs once every two weeks for 20 weeks (10 "relapse" tests). It was postulated that the daily cycles of morphine-abstinence and suppression of abstinence in the injection group only would generate latent interoceptively conditioned reinforcing properties of morphine because of conditioning of suppression of abstinence to the concomitant internal sensorial effects of morphine, which would persist after morphine withdrawal and be transferred to the internal effects of another opioid, etonitazene. It was found that across the first nine relapse tests, the injection group consumed significantly more etonitazene than the infusion group, while there were no significant differences in water consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Interoceptive conditioning through repeated suppression of morphine-abstinence. I. Basis for conditioning: once-daily vs. continuous intravenous morphine infusion.

Experimental evaluation of Wikler's interoceptive conditioning hypothesis of relapse to opioid use in ex-addicts requires a preliminary study of the degree of physical dependence produced by two methods of drug administration. Wistar rats were made physically dependent on morphine by single daily intravenous injections or by a continuous i.v. infusion. Rats received the same total daily dose regardless of administration schedule. The initial daily morphine dose was 20 mg/kg, and was increased every fourth day by 20 mg/kg, until a dose of 200 mg/kg per day was reached. The rats were maintained at the highest dose level for 18 days, at which time morphine was discontinued. Body weight and water intake were the primary variables measured during addiction, maintenance, and abstinence phases of the study. Equivalent and parallel changes in mean weight and water intake in injection and infusion rats indicate equivalent degrees of physical dependence were developed. This finding allows separation of the contribution of conditioning factors and of protracted abstinence in facilitating opioid self-administration in formerly-dependent organisms.

Animals↗