Repeated exposure to MDMA and amphetamine: sensitization, cross-sensitization, and response to dopamine D₁- and D₂-like agonists.

Rationale: Acute exposure to (±) 3, 4-methylenedioxymethamphetamine (MDMA) produces hyperlocomotion that is preferentially expressed in the periphery of closed chambers. Following repeated administration, however, a sensitized hyperlocomotor response is preferentially expressed in the center of an activity box, so that the response resembles the more generalized activity that is produced by D-amphetamine (AMPH).

Objectives: The present study was designed to determine whether common neuroadaptations underlie the acute and sensitized responses to MDMA and AMPH.

Effects of priming injections of MDMA and cocaine on reinstatement of MDMA- and cocaine-seeking in rats.

Exposure to self-administered drugs is sufficient to produce drug-seeking in animal models. In many cases priming injections of drugs that share discriminative stimulus properties with the self-administered drug also can lead to drug-seeking, suggesting that exposure might precipitate relapse. The present investigation examined the ability of MDMA or cocaine priming injections to reinstate extinguished drug-seeking in rats.

MDMA self-administration in rats: acquisition, progressive ratio responding and serotonin transporter binding.

3,4-Methylenedioxymethamphetamine (MDMA) self-administration has been shown in animals with extensive drug histories, but only a small number of studies have examined high rates of responding maintained by MDMA in previously drug-naïve animals. In the present study, influence of dose (0.25 or 1.

N-benzylpiperazine has characteristics of a drug of abuse.

The ability of benzylpiperazine (BZP) to substitute for cocaine and to initiate self-administration in drug-naive subjects was assessed to determine whether BZP has abuse liability. Further, the effects of a pretreatment with dopamine D1-like receptor antagonist (SCH23390) were examined to elucidate the mechanisms associated with BZP reward. First, the ability for BZP (0.

The effect of Parkinson's disease on time estimation as a function of stimulus duration range and modality.

The present research sought to investigate the role of the basal ganglia in timing of sub- and supra-second intervals via an examination of the ability of people with Parkinson's disease (PD) to make temporal judgments in two ranges, 100-500 ms, and 1-5 s. Eighteen non-demented medicated patients with PD were compared with 14 matched controls on a duration-bisection task in which participants were required to discriminate auditory and visual signal durations within each time range. Results showed that patients with PD exhibited more variable duration judgments across both signal modality and duration range than controls, although closer analyses confirmed a timing deficit in the longer duration range only.

Conditioning following repeated exposure to MDMA in rats: role in the maintenance of MDMA self-administration.

There has been some controversy in the literature concerning the ability of +/-3,4 methylenedioxymethamphetamine (MDMA) to reinforce operant responding in rats. In the present study, operant responding maintained by intravenous MDMA infusions increased when the fixed ratio schedule was increased from 1 to 5, decreased when saline was substituted for MDMA, and increased again when MDMA was reintroduced. During self-administration training, each infusion of MDMA was paired with the illumination of a light stimulus.

Development, maintenance and temporal pattern of self-administration maintained by ecstasy (MDMA) in rats.

Rationale: +/-3,4-Methylenedioxymethamphetamine (MDMA; "ecstasy") use is increasing around the globe but there is a paucity of studies examining the abuse liability of this drug.

Objectives: The ability of drugs to reinforce operant responding in laboratory animals is a valid and reliable predictor of abuse potential. MDMA is self-administered by humans, but there have been few reports of reliable self-administration by drug-naive laboratory animals.