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Biomedical subjects

G J Gerber

Publications and source records attributed to G J Gerber.

30 records · Page 2Linked to original sources
PubMed1977

Concurrent intracranial self-stimulation and amphetamine self-administration in rats.

In a two-lever testing chamber, rats had concurrent access to intravenous amphetamine and brain stimulation reinforcers. Responding for each reinforcer was generally increased above baseline rates taken when only one reinforcer was available. Amphetamine stereotypy was observed, but did not interfere with rapid lever-pressing for brain stimulation.

Amphetamine↗
PubMed1977

Discrete-trial control of morphine self-injection behaviour in monkeys: effects of injection dose and trials per session.

Responding for intravenous injections of morphine was studied using a discrete-trials procedure in squirrel monkeys. For one group, each session consisted of 10 trials at an inter-trial interval of 15 min; for the second group, each session consisted of 100 trials at an inter-trial interval of 1.5 min. When different injection doses of morphine (1-1000 mug/kg per injection), including saline as a control procedure, were substituted at random for blocks of five consecutive sessions, the frequency of morphine self-administration was found to be an inverted U-shaped function of the injection dose. This relationship was observed in each group of monkeys, despite a 10-fold difference in the total amount of the drug which was available for self-administration per session when a given injection dose was substituted for both groups. The results show that the injection dose of morphine acted as a primary determinant of response probability, even under circumstances in which trial spacing imposed a significant delay between consecutive opportunities for drug self-administration,

Animals↗
PubMed1976

Cocaine self-injection behaviour under schedules of delayed reinforcement in monkeys.

Rates of lever pressing, maintained either by response-dependent intravenous injections of cocaine (250 mug/kg per injection) or by food-pellet presentation, were compared and found to vary systematically as a function of the delay (5-100 s) imposed between the response(s) and the occurrence of reinforcement. The control of responding by two schedules of delayed reinforcement was studied. The first scedule permitted responses to occur during the delay period without any programmed consequence; the second schedule required a response, and then the elapse of x seconds without any additional response(s). At imposed delays of 50 and 100 s, response rates were reduced significantly when the second schedule was in effect by comparison with the first. The effect was observed when responding was maintained either by intravenous cocaine injections or by food-pellet presentation. Across all comparable conditions, response rates were higher when maintained by scheduled cocaine injections than by food pellets. Rate enhancement, generally induced by drugs of the psychomotor stimulant type, could account for the observed difference.

Animals↗
PubMedDate not supplied

Drug-induced reinstatement of extinguished self-administration behavior in monkeys.

Responding was established in squirrel monkeys under a modified progressive ratio schedule of IV d-amphetamine or cocaine self-administration. Subsituation of saline for the drug solutions resulted in extinction of the self-administration behavior. IV injections of certain doses of d-amphetamine or cocaine, immediately prior to test sessions in which response-contingent saline infusions were delivered, reinstated the rate and pattern of responding observed during sessions in which drug was self-administered. Presession IV injections of several doses of pentobarbital or chlorpromazine failed to consistently reinstate responding. These results were interpreted in terms of the discriminative control of drug self-administration behavior by the current drug state of the subject.

Animals↗
PubMedDate not supplied

Program outcome and QA: a new approach to evaluation.

Health care providers and managers are familiar with the limitations of current quality assurance (QA) practices, which do little to indicate the overall effectiveness of health care programs. This article discusses a comprehensive method of evaluating program effectiveness, efficiency, cost, client satisfaction, and adherence to standards. The authors present the Brockville Psychiatric Hospital's experience in evaluating a new program with data collected from a multi-faceted QA perspective, and suggest that combining program evaluation with QA could become the standard for future program assessments.

Community Mental Health Services↗
PubMedDate not supplied

Comparison of the behavioral effects of neurotoxic and systemically toxic agents: how discriminatory are behavioral tests of neurotoxicity?

The behavioral effects of carbon tetrachloride-produced impairment of liver function, insulin-produced reduction of plasma glucose levels, and the reduction of food and water intake have been evaluated. Considerable similarity was found among the behavioral effects of systemically toxic agents, three neurotoxicants (triethyltin, acrylamide, and 2,5-hexanedione), and the neuroleptic drug haloperidol. Measure of motor strength differentiated neurotoxic from non-neurotoxic compounds, while measures of motor activity were equally sensitive to neurotoxic, systemically toxic, and non-neurotoxic agents. These findings demonstrate the importance of assessing systemic toxicity before drawing conclusions about the neurotoxicity of a behaviorally active compound.

Animals↗
PubMedDate not supplied

Triethyltin-produced decrease and recovery of wheel running and food-reinforced lever pressing in rats.

Behavioral effects of triethyltin were studied in rats living in Wahmann activity cages. Wheel running activity and food-reinforced lever pressing were recorded 23 hr/day from 4 rats. Triethyltin injections (4 mg/kg IP) produced large transient decreases in running, lever pressing, and daily water consumption, without affecting body weight. These measures recovered to pre-treatment levels within 1-2 days. After 4 weekly injections, wheel running was reduced in 2 rats, and increased in 1 rat, while lever pressing remained at baseline levels. Good correlation was noted between the extent of reductions in wheel running and lever pressing, and the extent of characteristic triethyltin-induced morphological lesions in the central and peripheral nervous system. Over the course of repeated treatments, several critical behaviors known to be sensitive to neurotoxicants can be continually monitored using automated testing apparatus. While further validation with more compounds is required, these results suggest that monitoring wheel running, food-reinforced lever pressing, and water consumption may be an inexpensive way to test for behavioral neurotoxicity using small numbers of animals.

Animals↗