Influence of novel and habituated testing conditions on cocaine sensitization

Abstract

Female Swiss-Webster mice were treated daily for 10 days with cocaine (15 m g/kg i.p.) followed by 10 days with saline or ethanol (1.6 g /kg i.p.) or the reverse; following each injection in the experimental conditions locomotion was quantified in photocell cages. In animals given cocaine first, cocaine-induced locomotion was initially high and did not increase further with successive injections. In animals given prior saline or ethanol treatments, cocaine-induced locomotion was initially low but increased with successive cocaine treatments, There was no evidence of sensitization to the locomotor-stimulating effects of ethanol or of cross-sensitization between ethanol and cocaine. With respect to subsequent cocaine sensitization, the essential feature of prior saline or ethanol treatment appeared to be the handling and injection experience itself; a control group receiving prior saline injections in the home cage also showed a low level of cocaine-induced locomotion on the first day of cocaine testing but increasing locomotion with repeated cocaine testing. Thus, cocaine sensitization, rather than a progressive augmentation of motor function, may reflect a progressive reversal of the behavioral suppression caused by habituation to aspects of the testing situation or to some form of situational anxiety that precludes normal exploratory responses.

Repeated alcohol: behavioral sensitization and alcohol-heightened aggression in mice

“…Induction of locomotor sensitization has been detected in outbred mice only with alcohol doses between 2.0 g/kg and 2.5 g/kg (Wise et al 1996;Lessov and Phillips 1998;Gevaerd and Takahashi 1999;Itzhak and Martin 1999;Souza-Formigioni et al 1999;Grahame et al 2000). However, expression to a 2.0-g/kg alcohol challenge has been observed in mice given repeated doses greater than or equal to 2.75 g/kg (Masur and Boerngen 1980;Grahame et al 2000).…”

Effects of periadolescent versus adult cocaine exposure on cocaine conditioned place preference and motor sensitization in mice

“…The lack of sensitization in the adult mice is most likely attributable to a lack of habituation to the testing environment. Wise et al (1996) have shown with Swiss-Webster mice that habituation to the testing chambers with saline injections facilitates sensitization to subsequent cocaine injections. This is consistent with our results in the conditioning phase of CPP, where we do observe sensitization when cocaine association training is interleaved with saline association training.…”

Withdrawal From Intermittent Ethanol Exposure Increases Probability of Burst Firing in VTA Neurons In Vitro

“…We should note that not all studies examining repeated ethanol injection have observed subsequent enhanced locomotor activation by cocaine (Lessov and Phillips 2003;Wise et al 1996). However, as noted by Lessov and Phillips (2003), the drug treatment schedules and time of testing for sensitization vary widely across these studies, making comparisons difficult.…”