Biomedical subjects

R J Dacanay

Publications and source records attributed to R J Dacanay.

7 recordsLinked to original sources

PubMed1989

Conditioned taste aversions as a behavioral baseline for drug discrimination learning: an assessment with phencyclidine.

When PCP was given prior to the pairing of saccharin with LiCl (and the PCP vehicle prior to a nonpoisoned exposure to the same saccharin solution), rats rapidly acquired the discrimination, avoiding saccharin consumption following PCP and consuming saccharin following the vehicle after only three conditioning trials. Conversely, when the PCP vehicle was given prior to the saccharin-LiCl pairing and PCP prior to a nonpoisoned exposure to saccharin, other subjects avoided saccharin consumption following the vehicle injection and readily consumed saccharin after an injection of PCP. During dose substitution sessions, animals displayed greater drug-appropriate responding as the dose of PCP increased. When a range of doses of ketamine was given in place of PCP prior to saccharin access, subjects displayed dose-dependent PCP-appropriate responding. When a range of doses of d-amphetamine was substituted for PCP, subjects displayed vehicle-appropriate responding at all doses. The relative efficacy of the taste aversion procedure as a baseline for drug discrimination learning is discussed.

Animals↗

PubMed1984

Opiate withdrawal: the result of conditioning or physiological mechanisms?

Although it has been suggested that opiate withdrawal responses might be conditioned compensatory responses elicited by drug-associated stimuli, the present results do not support such a view. Withdrawal, as measured by an aversion to a saccharin solution following the termination of morphine administration, occurred independent of the presence of morphine-paired environmental or temporal cues. These results suggest that withdrawal is most likely the result of some physiological mechanism, rather than the result of conditioning.

Animals↗

PubMed1984

The effects of trimethyltin chloride on the acquisition of long delay conditioned taste aversion learning in the rat.

Naive rats injected with LiCl at various times following consumption of a novel saccharin solution subsequently avoided the ingestion of saccharin with the degree of the aversion related to the interval between ingestion and LiCl administration. Although a similar relationship was also evident in animals which had received a single intragastric administration of trimethyltin chloride 21 days prior to the pairing of saccharin and LiCl, the trimethyltin-pretreated subjects receiving delayed injections of LiCl displayed weaker taste aversions than those not exposed to trimethyltin. This disruption in the acquisition of taste aversions over long delays is consistent with other work suggesting that trimethyltin disrupts tasks involving short-term memory. The utility of the conditioned taste aversion paradigm in detecting and characterizing drug toxicity was discussed.

Animals↗

PubMed1982

Incentive processes and the peak shift.

Intradimensional operant discrimination schedules were employed, which eliminated the covariation of response and reinforcement rates that are found on most operant baselines. In Phase 1, one keylight (S(1)) controlled an increase in pigeons' treadle pressing, relative to another keylight (S(2)), while being correlated with a decrease in frequency of reinforcement. In Phase 2 both treadle pressing and reinforcement increased in the presence of one keylight, relative to the second. In Phase 1 the relatively flat treadle-press generalization gradients peaked at S(1), whereas the peaks of those in Phase 2 were shifted from S(1) in a direction away from S(2). It was postulated that these positive and negative stimulus-reinforcement contingencies influence the likelihood of obtaining peak shift through the operation of a classically conditioned "central motive state." How response-reinforcement and stimulus-reinforcement contingencies might contribute to the development of inhibitory effects of S(2) is discussed. Autoshaped key pecking also was produced by these procedures. During manipulations of stimuli, the gradients obtained for autoshaped key pecking were narrow and sharply peaked at the food-correlated stimulus (S(2)) in Phase 1. This failure to obtain peak shift for an elicited response suggests a difference in discriminative processes operating in classical and instrumental learning.

Journal Article↗

PubMedDate not supplied

Effects of trimethyltin chloride on the LiCl dose-response function for conditioned taste aversions in rats.

Twenty-one days following intragastric administration of 6.0 mg/kg of TMT (TMT chloride base/kg) or equivolume distilled water, groups of rats were injected with various doses of LiCl (0, 0.15, 0.60 or 1.8 mEq/kg) following the consumption of a novel saccharin solution. Both groups subsequently avoided the consumption of saccharin, with the degree of the aversion directly related to the dose of LiCl. Further, there was no difference between the TMT- and non-TMT-treated rats in the degree of aversion at any dose. These data suggest that the previously-reported effect of TMT on long-delay taste aversion learning was not likely due to changes in sensory responsiveness.

Animals↗

PubMedDate not supplied

Sex differences in taste aversion learning: an analysis of the minimal effective dose.

Male and female rats injected with various doses of LiCl following the consumption of a novel saccharin solution subsequently avoided consumption of saccharin, with the degree of the aversion directly related to the dose of LiCl. Although this dose-response relationship was evident for both males and females, the minimal effective dose for inducing an aversion was lower for males, an effect consistent with previous work examining sex differences in taste aversion learning. The necessity of considering sex as a variable when comparing the relative sensitivity of behavioral measures of toxicity was discussed.

Animals↗

PubMedDate not supplied

Effects of trimethyltin chloride on differential-reinforcement-of-low-rate responding.

The effects of a range of doses of trimethyltin chloride (1.8-7.0 mg/kg, TMT) on responding maintained under a differential-reinforcement-of-low-rate 15-sec schedule of water presentation were examined in rats. TMT produced a large decrease in the percent of reinforced responses and consequently a decrease in the rate of reinforcement. These effects were due primarily to prolonged bursts of nonreinforced responses. In contrast to the gradual dose-related decrease in body weight produced by TMT, responding was disrupted only at the highest dose tested, i.e., 7.0 mg/kg. The results were discussed in terms of the neurotoxic effects of TMT on the limbic system.

Animals↗