Mesolimbic dopaminergic tract

Nucleus accumbens A forebrain structure innervated by a branch of the mesolimbic dopaminergic tract, implicated in reward and motivation. 

Postmortem studies of patients with idiopathic Parkinson s disease demonstrate cell loss in the striatal system (A-9), directly implicating this tract vis-a-vis the neuroleptic-induced pseudoparkinsonian side effects. The assumption that psychosis is related to the A-10 system is made by exclusion. Evidence also indicates that clozapine may differentially block DA pathways. Specifically, it seems to act on the mesolimbic dopaminergic system (A-10), while being relatively inactive in the striatal system (A-9) however, this remains controversial. Chronic administration of clozapine decreases the firing rate of A-10 mesocortical tract dopamine neurons... 

The working assumption that the striatal system is only involved with extrapyramidal function (e.g., parkinsonian side effects, dystonias, and TD) and that the mesolimbic or mesocortical systems are only involved with psychosis may be an oversimplification. Many of the neuroanatomical studies on the identified dopaminergic tracts are done with rats. In the monkey, by contrast, there are many more DA tracts that are either absent in the rat or at least markedly different human systems could be different from the rat s or monkey s. Understanding the neuropharmacology of the antipsychotics is further complicated, given that neither the mesolimbic-mesocortical nor the striatal systems are homogeneous but may also include various subsystems. 

Activate opioid jj., k, and 8 receptors. Potent (1 receptor activators have the most intense abuse and dependence liability, possibly effected via an increase in dopaminergic transmission in the mesolimbic tracts... 

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