Endogenous opioids reward systems

Endogenous opioid systems are an integral part of the reward circuitry 916 PSYCHOMOTOR STIMULANTS 916... 

The behavioral effects of nicotine have been defined as both stimulant and depressant, effects that are influenced by the present mental status and expectations of the smoker. Smokers may feel alert and relaxed. Nicotine produces myriad effects on the central nervous system (CNS), almost all of which appear to be mediated through nicotinic receptors. Additionally, nicotine influences multiple neuronal systems. One of its most prominent effects is stimulated release of dopamine, particularly in the nucleus accumbens, which is a major component of the reward system. Nicotine also stimulates the release of endogenous opioids and glucocorticoids. 

Additionally, an opioid antagonist, naltrexone, has been used to treat children with autism. The results from these studies have been mixed, with some studies showing a mild decrease in hyperactivity and self-injurious behavior, and improved attention (Gillberg, 1995). The children who respond best to this medication appear to have more severe abnormalities in their beta endorphin levels (Bouvard et al., 1995). Overall, the research suggests that the endogenous opioid system, which is important in the reward aspects of affiliation, may also play a role in the neurobiology of autism. 

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