Behavioral effects opioid systems

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. 

Opioid systems contribute to the regulation of naturally reinforced behaviors (i.e., sexual behavior, feeding, drinking, and social behavior) (Rodgers and Cooper, 1988) and to the rewarding effects of artificial reinforcers, such as chemical rewards as cocaine and ethanol (van Ree et ah, 1999). 

ROLE OF DELTA OPIOID RECEPTORS IN THE BEHAVIORAL EFFECTS OF DUAL INHIBITORS— INTERACTION WITH THE DOPAMINERGIC SYSTEM... 

Benzodiazepines have a high therapeutic index of safety, with little effect on most systems (other than the CNS) in high doses. However, their toxicity increases markedly when they are combined with other CNS depressant drugs, such as alcohol or opioid analgesics. Medically ill and brain injured patients are particularly susceptible to adverse neurological or behavioral effects (SEDA-18, 43 SEDA-20, 30 46). 

Umide Demir Ozkay, Ozgiir Devrim Can, Anti-nociceptive effect of vitexin mediated by the opioid system in mice. Pharmacology, Biochemistry and Behavior 109 (2013), p. 23-30. 

In rodents, PCP produces not only ataxia, but also stereotyped behavior and hyperactivity. The PCP-induced stereotyped behavior is thought to be due to changes in serotonergic and dopaminergic systems (Nabeshima et al. 1983 Martin et al. 1979 Sturgeon et al. 1981). It is not known whether PCP receptors mediate PCP-induced hyperactivity or stereotyped behavior or even the effect on neurotransmitter systems. It is also possible that mu, kappa, or sigma opioid receptors are involved (Castellani et al. 1982). 

Emotional effects Morphine creates a pleasant, euphoric state, which is an aspect of the behaviorally reinforcing effect. The subjective state produced by opioids is often described as ecstatic and is compared to a sexual experience. These effects are most likely mediated by iJ and possibly 5 receptors, and interactions with the mesolimbic dopamine system (Shippenberg et al. 1993 Di Chiara and North 1992 Wise 1989). In contrast, x opioids have dysphoric and psychotomimetic effects (Kumor et al. 1986). 

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