This study examined the involvement of the brain stress system in the reinforcing effects of morphine. One group of mice was conditioned to morphine using the conditioned place preference (CPP) paradigm and the other group received morphine in a home-cage (non-conditioned). Adrenocorticotropic hormone and corticosterone levels were measured by radioimmunoassay; phospho (p) CREB expression and t...

RATIONALE Evidence suggests that 4 weeks of voluntary wheel running abolishes conditioned place preference (CPP) for cocaine in male C57BL/6J mice. OBJECTIVES To determine the duration and timing of exposure to running wheels necessary to reduce CPP, and the extent to which the running per se influences CPP as compared to environmental enrichment without running. METHODS A total of 239 male...

The anterior cingulate cortex (ACC) is known for its role in perception of nociceptive signals and the associated emotional responses. Recent optogenetic studies, involving modulation of neuronal activity in the ACC, show that the ACC can modulate mechanical hyperalgesia. In the present study, we used optogenetic techniques to selectively modulate excitatory pyramidal neurons and inhibitory int...

It has been shown that L-arginine like the abused drugs could release dopamine from meso-cortico-limbic system. The purpose of the present study was to compare the effect of L-arginine with morphine as a standard abuse drug in the induction of conditioned place preference (CPP) in rat. For this purpose, male Wistar rats (250-300 g) were used in the experiments. Five days after surgical cannulat...

Drug seeking and the vulnerability to relapse occur when individuals are exposed to an environment with sensory cues in which drug taking has occurred. Memory formation is thought to require plasticity in synaptic circuits, and so we examined whether the memory for a drug-paired environment correlates with changes in the synaptic circuits of the basolateral amygdala (BLA), in which emotional le...

OBJECTIVE The noradrenaline system is involved in the reward effects of various kinds of abused drugs. Betaxolol (BTX) is a highly selective β1-antagonist. In the present study, we evaluated the effect of BTX on methamphetamine (MAP)-induced conditioned place preference (CPP) and hyperactivity in mice. METHODS The mice (n=72) were treated with MAP or saline every other day for a total of 6 da...

Chronic physical activity (exercise) may be beneficial in the prevention of substance use disorders; however, the extent to which physical activity can interfere with the reinforcing effects of drugs during the adolescent period, which is one of great vulnerability for drug experimentation, has not been fully evaluated. Here, we assess the effects of chronic forced exercise during adolescence o...

Nucleus accumbens (Nac) has been considered as a center for the induction of drug dependence. Since a high concentration of the enzyme, nitric oxide synthase (NOS) has been found in the Nac, and this fact that the role of nitric oxide (NO) in acquisition and expression of drug dependence has become clear in recent years, therefore in this study the effects of intraaccumbal injections of L-argin...