The ventral tegmental area (VTA) plays a critical role in motivated behavior. However, it remains unclear whether intact VTA function is necessary for motivated behavior to seek contexts repeatedly paired with natural stimuli and/or pharmacological stimuli. In the present study, conditioned place preference (CPP) was induced with highly salient natural or drug stimuli attributed with strong inc...

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...

There is much evidence that naturally occurring behaviors (e.g., the ingestion of food and water) and social behaviors (e.g., play, maternal behavior) can induce a reward state. This review includes definitions to distinguish between "reward" and "reinforcement," and a description of methods to assess reward and demonstrate that social interactions can indeed produce a positive affective (PA) s...

Sigma receptor antagonists diminish the effects of cocaine in behavioral assays, including conditioned place preference. Previous locomotor activity experiments in mice determined that the sigma receptor ligand YZ-185 (N-phenylpropyl-N'-(3-methoxyphenethyl)piperazine) enhanced cocaine-induced hyperactivity at a lower (0.1  μ mol/kg) dose and dose-dependently attenuated cocaine-induced hyperacti...

Conditional responses in rodents such as locomotion have been reported for drugs of abuse and similar to the placebo response in humans, may be associated with the expectation of reward. We examined several conditional opioid-like responses and the influence of drug expectation on conditioned place preference and concomitant conditional locomotion. Male C57BL/6J mice were conditioned with the s...

Association between the reward caused by consuming drugs and the context in which they are consumed is essential in the formation of morphine-induced conditioned place preference (CPP). Glucocorticoid receptor (GRs) activation in different regions of the brain affects reward-based reinforcement and memory processing. A wide array of studies have demonstrated that blockage of GRs in some brain a...

We previously developed rat experimental models based on the conditioned place preference (CPP) paradigm in which only four 15-min episodes of dyadic social interaction with a sex- and weight-matched male Sprague Dawley (SD) rat (1) reversed CPP from cocaine to social interaction despite continuing cocaine training, and (2) prevented the reacquisition/re-expression of cocaine CPP. In a concurre...

Objective: Opiate addiction is characterized by compulsive drug use and severe withdrawal symptoms during abstinence. Heantos 4, an herbal pharmacotherapy recently approved for opiate withdrawal treatment in Vietnam, has shown anti-craving properties. The present study is the first preclinical assessment of the effects of Heantos 4 on opiate withdrawal and the rewarding properties of morphine, ...

Metabotropic glutamate receptor 5 (mGluR5) null mutant (-/-) mice have been reported to totally lack the reinforcing or locomotor stimulating effects of cocaine. We tested mGluR5 -/and +/+ mice for their locomotor and conditioned placepreference response to cocaine. Unlike the previous finding, here we show that compared to mGluR5 +/+ mice, -/mice exhibit no difference in the locomotor response...

INTRODUCTION The present study aimed to determine if, as occurs in female rats, progesterone attenuates cocaine-induced reward and psychomotor responses in male rats. METHODS The role of progesterone in the acquisition and/or expression of cocaine-induced conditioned place preference (CPP) and locomotor responses of intact male rats was studied. For chronic progesterone treatment, rats receiv...