Electrical stimulation mPFC affects morphine addiction by changing glutamate concentration in the ventral tegmental area

Endocannabinoids and addiction memory: Relevance to methamphetamine/morphine abuse

AIM

This review aims to summarise the role of endocannabinoid system (ECS), incluing cannabinoid receptors and their endogenous lipid ligands in the modulation of methamphetamine (METH)/morphine-induced memory impairments.

METHODS

Here, we utilized the results from researches which have investigated regulatory role of ECS (including cannabinoid receptor agonists and antagonists) on METH/morphine-induced memory impairments.

RESULTS

Among the neurotransmitters, glutamate and dopamine seem to play a critical role in association with the ECS to heal the drug-induced memory damages. Also, the amygdala, hippocampus, and prefrontal cortex are three important brain regions that participate in both drug addiction and memory task processes, and endocannabinoid neurotransmission have been investigated.

CONCLUSION

ECS can be regarded as a treatment for the side effects of METH and morphine, and their memory-impairing effects.

The Antagonism of Corticotropin-Releasing Factor Receptor-1 in Brain Suppress Stress-Induced Propofol Self-Administration in Rats

Propofol addiction has been detected in humans and rats, which may be facilitated by stress. Corticotropin-releasing factor acts through the corticotropin-releasing factor (CRF) receptor-1 (CRF1R) and CRF2 receptor-2 (CRF2R) and is a crucial candidate target for the interaction between stress and drug abuse, but its role on propofol addiction remains unknown. Tail clip stressful stimulation was performed in rats to test the stress on the establishment of the propofol self-administration behavioral model. Thereafter, the rats were pretreated before the testing session at the bilateral lateral ventricle with one of the doses of antalarmin (CRF1R antagonist, 100–500 ng/site), antisauvagine 30 (CRF2R antagonist, 100–500 ng/site), and RU486 (glucocorticoid receptor antagonist, 100–500 ng/site) or vehicle. The dopamine D1 receptor (D1R) in the nucleus accumbens (NAc) was detected to explore the underlying molecular mechanism. The sucrose self-administration establishment and maintenance, and locomotor activities were also examined to determine the specificity. We found that the establishment of propofol self-administration was promoted in the tail clip treated group (the stress group), which was inhibited by antalarmin at the dose of 100–500 ng/site but was not by antisauvagine 30 or RU486. Accordingly, the expression of D1R in the NAc was attenuated by antalarmin, dose-dependently. Moreover, pretreatments fail to change sucrose self-administration behavior or locomotor activities. This study supports the role of CRF1R in the brain in mediating the central reward processing through D1R in the NAc and provided a possibility that CRF1R antagonist may be a new therapeutic approach for the treatment of propofol addiction.

Similar role of mPFC orexin-1 receptors in the acquisition and expression of morphine- and food-induced conditioned place preference in male rats

Self-control problems are a typical character of drug addiction and excessive food consumption and it has been shown that natural rewards and drugs of abuse share parts of the same neural substrate and reward processing in the brain. Different brain areas are involved in natural and drug reward processing including the mesolimbic pathway, amygdala, nucleus accumbens (NAc), and prefrontal cortex. Considering the important role of orexins in the addictive behavior and the presence of orexin-1 subtype receptors (Orx1R) in the medial prefrontal cortex (mPFC), this study investigated the role of mPFC in natural- and drug-reward seeking behaviors to deepen our understanding of possible similarities or differences. To induce food- or morphine-conditioned place preference (CPP), adult male Wistar rats underwent CPP testing and received intra-mPFC doses of SB334867 (3, 10, or 30 nM/0.5 μl DMSO 12%), as an Orx1R antagonist, during the acquisition or expression phases of the CPP test. Results indicated that microinjection of Orx1R antagonist into the mPFC had similar effects on both morphine- and food-induced CPP and attenuated CPP scores in the acquisition and expression phases of the CPP test. The data demonstrated that Orx1Rs in the mPFC regulate the reward-related effects of morphine- and food-induced reward.