Conditioning of and contextual sensitization to apomorphine-induced climbing in mice : evidence against the habitation hypothesis

in Behavioral Neuroscience (1999), 113(2), 368-376

Several predictions of the habituation hypothesis of conditioned drug effects were tested by looking at contextual sensitization to apomorphine-induced climbing in mice (Mus musculus). Mice were first ... [more ▼]

Several predictions of the habituation hypothesis of conditioned drug effects were tested by looking at contextual sensitization to apomorphine-induced climbing in mice (Mus musculus). Mice were first sensitized to that effect after 9 daily injections of 0.4 mg/kg apomorphine in the test context. Other mice received the same treatment outside the test context. On Day 10, all mice were challenged with either saline (conditioned drug effects test) or apomorphine (contextual sensitization test). On both tests, the levels of climbing of mice that received apomorphine paired with the test context during the intermittent treatment were significantly higher than those of mice that were experiencing the test context for the first time (unexposed mice). Also, the rate of extinction in conditioned mice did not parallel the rate of habituation in the unexposed mice. Results contradict the habituation hypothesis of conditioned drug effects and contextual sensitization. ((c) 1999 APA/PsycINFO, all rights reserved)(journal abstract) [less ▲]

Conditioned apomorphine-induced climbing: Influence of cue-exposure and the contribution of "forgetting" to the effects observed

in Behavioural Pharmacology (1999), 10

Conditioned cocaine effects and lack of habituation to the context in one- and two-week-old rat pups : présentée au Joint Meeting of the Behavioural Pharmacology Society and the European Behavioural Pharmacology Society, Boston, USA, September 1-5, 1999

in Behavioural Pharmacology (1999)

Contexual sensitization to the behavioral effects of cocaine in neonatal rats

in Developmental Psychobiology (1999), 25

Evidence for behavioral sensitization to cocaine in preweanling rat pups

in Psychopharmacologia (1998), 138(2), 114-123

Sought to determine whether promoting context-dependent sensitization might facilitate expression of sensitization in preweanlings. Sprague-Dawley rats were injected daily from postnatal day 14 to ... [more ▼]

Sought to determine whether promoting context-dependent sensitization might facilitate expression of sensitization in preweanlings. Sprague-Dawley rats were injected daily from postnatal day 14 to postnatal day 20 with 0, 5, 15, or 30 mg/kg cocaine hydrochloride and placed for 30 min in either the experimental chamber or home cage. On postnatal day 21 (test day), Ss were challenged with either 15 mg/kg cocaine or saline prior to placement in the experimental chamber. Significant sensitization of cocaine-induced stereotyped head movements was evident in animals given 15 or 30 mg/kg chronically in the experimental chamber, but not when these same doses were given in the home cage. Less consistent evidence for cocaine-induced sensitization was seen when examining locomotion, although trends for sensitization of this behavior were seen in animals chronically injected in either the test chamber or home cage. Thus, preweanlings can exhibit cocaine sensitization, particularly in terms of stereotypy, when tested shortly after the chronic exposure period, with expression of this sensitization being facilitated by pairing the chronic injections with the test context. ((c) 1998 APA/PsycINFO, all rights reserved) [less ▲]

Ontogeny of acute sensitization to cocaine in rats

in Behavioural Pharmacology (1998), 9

Gamma-aminobutyric acid-sub(A) agonists differentially gnawing induced by indirect-acting dopamine agonists in C57BL/6J mice

in Journal of Pharmacology and Experimental Therapeutics (The) (1998), 284(1), 116-124

Evaluated the interaction of either gaboxadol HCl (THIP) or muscimol, both gamma-aminobutyric acid (GABA) type A agonists, with indirect-acting dopamine agonists (DAGs) methylphenidate, (+)-amphetamine ... [more ▼]

Evaluated the interaction of either gaboxadol HCl (THIP) or muscimol, both gamma-aminobutyric acid (GABA) type A agonists, with indirect-acting dopamine agonists (DAGs) methylphenidate, (+)-amphetamine, metamphetamine, amfonelic acid, indatraline, nomifensine, diclofensine, mazindol, and GBR 12935 and with direct-acting DAGs WIN 35,428, bupropion, GBR 12909, and cocaine. 1,832 male C57BL/6J mice were given either with saline or 1 of the doses of THIP or muscimol before an injection of a dopamine agonist. Gnawing on corrugated packing paper was measured. Results showed that: (1) indirect- but not direct-acting DAGs induced gnawing, (2) gnawing induced by indirect-acting DAGs GBR 12935, nomifensine and mazindol was potentiated in mice in which GABA type A receptors were stimulated either by THIP or muscimol, and (3) indirect DAGs had a differential sensitivity to the effects of THIP and muscimol. ((c) 1998 APA/PsycINFO, all rights reserved) [less ▲]

Neonatal and Preweanling Rats Are Able to Express Short-Term Behavioral Sensitization to Cocaine

in European Journal of Pharmacology (1997), 328(2-3), 103-14

The present study assessed the ability of suckling rats to express short-term behavioral sensitization to cocaine prior to weaning. Rat pups, aged either 3, 5, 10, 12, 17 or 19 days at the beginning of ... [more ▼]

The present study assessed the ability of suckling rats to express short-term behavioral sensitization to cocaine prior to weaning. Rat pups, aged either 3, 5, 10, 12, 17 or 19 days at the beginning of the experiment, were placed in a chamber after daily injection with cocaine (7.5 or 15 mg/kg. i.p.) for either 2 or 4 consecutive days, and were tested for behavioral responsiveness to cocaine in the same chamber 24 h later (at either 7, 14 or 21 days of age). Such a short post-treatment interval was adopted, along with a consistent pairing of the testing context with the drug effect and a sensitive technique of behavioral measurement (video recording), in order to maximize the possibility of detecting any cocaine sensitization. Locomotion was sensitized at all ages, after both regimens in 14-day-old pups, but solely after 2 injections in 21- and 4 injections in 7-day-old pups. Sensitization was also expressed via behaviors specific to each age. Four cocaine injections augmented cocaine-induced uncoordinated movements of head, paws and body (horizontal activity) in 7-day-old pups, and mouth movements in 14-day-old pups. In 21-day-old pups, sensitization was dose- and regimen-dependently expressed via adult-like stereotyped head movements. In neonatal 7-day-old pups, cocaine sensitization was also visible as reductions in immobility (both injection regimens). Contrary to previous studies, these results indicate that, given the use of an appropriate methodology, short-term sensitization to the motoric effects of cocaine can be expressed by suckling rats prior to weaning, even after relatively short regimens of daily injections. [less ▲]

Evidence for a non-involvement of the dopamine D-3 receptors in the acute psychostimulant effects of cocaine : implications for the dopaminergic theory of addiction

in Behavioural Pharmacology (1997), 5

Differential effects of cocaine and dopaminergic agonists on hypokinesia induced by dopaminergic antagonists

in National Institute on Drug Abuse Research Monograph Series (1996), 142