| Summary: | Introduction: Studies on the mechanisms of the reinforcing action of opioid and non-opioid narcotics confirmed the existence in the brain of a specialized system named the extended amygdala.
Materials and methods: To clarify the value of the extended amygdala structures (bed nucleus, central nucleus of the amygdala and nucleus accumbens shell) in the mechanisms of unconditioned and conditioned reinforcement activated by various narcogenic, this paper carried out a neuropharmacological analysis of these effects, using blockade of dopamine receptors, GABA, opioids and CRF receptors within these brain structures, as well as an analysis of behavioral responses by self-stimulation (unconditioned reinforcement) and conditioned place preference (CPP) (conditioned reinforcement).
Results and discussion: The central amygdala and the bed nucleus have a controlling influence on the hypothalamus, which is predominantly of CRF-, GABA- and dopaminergic nature. Through D1 dopamine receptors,, a direct positive (activating) effect on the lateral hypothalamus is made. The D2 receptor blockade of the nucleus accumbens prevents narcogenic from exerting the reinforcing properties, which are primarily stimulating. The blockade of the D1 receptors of the nucleus accumbens by SCH-23390 prevents the expression of unconditioned and conditioned reinforcing properties of predominantly opiates and opioids. The blockade of GABAA receptors in the nucleus accumbens with bicuculline prevents the manifestation of the primary and secondary reinforcing properties (CPP) of psychostimulant drugs (amphetamine), without affecting the effects of opiates and opioids (fentanyl and leu-enkephalin).
Conclusion: The pharmacological analysis proves that CRF, dopamine and GABA receptors are most important for the correction of reinforcement activated by various narcogenic.
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