Environmental novelty modulates the induction and expression of single injection-induced behavioral sensitization to morphine.

Opioid addiction is a growing public health problem, being currently considered an epidemic in the United States. Investigating the behavioral effects of opioids and the factors influencing their development becomes of major importance. In animals, the effects of drugs of abuse can be assessed using the behavioral sensitization model, which shares similar neuronal substrates with drug craving in humans.

Differential effects of intermittent and continuous exposure to novel environmental stimuli on the development of amphetamine-induced behavioral sensitization in mice: implications for addiction.

Background: Previous studies have demonstrated a preventive effect of continuous environmental enrichment during early development on the vulnerability of rodents to drug addiction-related behaviors. Recently, it was demonstrated that a continuous environmental enrichment could eliminate already established addiction-related behaviors in mice. The present study compared the effects of intermittent or continuous exposure to novel stimuli during repeated amphetamine (Amp) treatment on the development of behavioral sensitization (an animal model of addiction-related neuroadaptations) in adult mice.

Effects of group exposure on single injection-induced behavioral sensitization to drugs of abuse in mice.

Background: Behavioral sensitization in rodents is hypothesized to reflect neuronal adaptations that are related to drug addiction in humans. We evaluated the effects of group exposure on the acute hyperlocomotion and behavioral sensitization induced by four drugs of abuse in C57BL/6 mice: methylenedioxymethamphetamine (MDMA), d-amphetamine, morphine and ethanol.

Methods: In the priming session, animals received an ip injection of one of the drugs of abuse and were exposed to an open field either individually or in groups of four.

Reciprocal interactions between MK-801, sleep deprivation and recovery in modulating rat behaviour.

Increasing evidence indicates that sleep deprivation alters behavioural responses to various pharmacological agents which might be associated to changes in receptor systems. The present work addressed the effects of sleep deprivation and recovery on behavioural changes induced by MK-801, and investigated whether such effects are related to changes in NMDA receptor (NMDAR) binding. Male Wistar rats were deprived of sleep for 96 h using the platform method (SD group), or were sleep deprived and then allowed to recover sleep for 24 h (SR group).

Long-term haloperidol treatment (but not risperidone) enhances addiction-related behaviors in mice: role of dopamine D2 receptors.

The high prevalence of psychostimulant abuse observed in schizophrenic patients may be related to the development of mesolimbic dopaminergic supersensitivity (MDS) or nigrostriatal dopaminergic supersensitivity (NDS) in response to the chronic blockade of dopamine receptors produced by typical neuroleptic treatment. We compared the effects of withdrawal from long-term administration of the typical neuroleptic haloperidol (Hal) and/or the atypical agent risperidone (Ris) on MDS and NDS, behaviorally evaluated by amphetamine-induced locomotor stimulation (AILS) and apomorphine-induced stereotypy (AIS) in mice, respectively. We further evaluated the duration of MDS and investigated the specific role of dopamine D2 receptors in this phenomenon by administering the D2 agonist quinpirole (Quin) to mice withdrawn from long-term treatment with these neuroleptics.