Neurotransmitter system dopaminergic systems

GABAergic neurons are inhibitory, and a loss of these inhibitory effects can produce, at least in part, the overactivity seen with other neurotransmitter systems (dopaminergic, serotonergic, and possibly adrenergic). For a complete overview, see Section 4.2. 

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). 

The administration of low doses of PCP to rodents induces hyperactivity and stereotypy (Chen et al. 1959 ). The observation that neuroleptics such as chlorpromazine, haloperidol, and pimozide, and adrenolytics such as alpha-methyl paratyrosine antagonize these behavioral effects of PCP suggests that they are mediated by facilitation of central dopaminergic neurotransmission (Murray and Horita 1979). The actions of PCP on central dopaminergic neurotransmission may be similar to amphetamine. A dose of PCP (2.5 mg/kg) in rats, which has no effects when given alone, enhances the behavioral effects of 1 and 3 mg/kg of d-amphetamine (Balster and Chait 1978). PCP, like dopamine, has also been shown to suppress plasma prolactin (Bayorh et al. 1983). However, the firm establishment of an excl usive relationship between dopamine neuro-transmission and PCP effects is difficult because of the prominent interactions of this drug with other neurotransmitter systems. 

Cory-Slechta DA. 1995a. Relationships between lead-induced learning impairments and changes in dopaminergic, cholinergic, and glutamatergic neurotransmitter system functions. Annu Rev Pharmacol Toxicol 35 391-415. 

Dopamine is a catecholamine neurotransmitter in the CNS and at some ganglia in the autonomic nervous system. To date, three main types of receptors have been found D1( D2, and D3. The main dopaminergic systems in the brain are the nigro-neostriatal... 

Corrigall WA, Franklin KB, Coen KM, Clarke PB. (1992). The mesolimbic dopaminergic system is implicated in the reinforcing effects of nicotine. Psychopharmacology (Berlin). 107(2-3) 285-89. Dackis C, Gold MS. (1985). Neurotransmitter and neuroendocrine abnormalities associated with cocaine use. Psychiatr Med. 3(4) 461-83. 

Tourette s syndrome is a well-studied condition, characterized by motor and phonic tics and by behavioral and psychological problems. While many neurotransmitters were implicated in the etiology of this disorder, it is now believed that the dopaminergic system and noradrenergic systems are involved. Two major clinical trials (Shapiro et ah, 1989 Sallee et al, 1997) indicated that haloperidol and pimozide reduced the severity of tics by 65%. However, these medications are associated with side effects (including possible cognitive impairment, sedation, dysphoria, and tardive dyskinesia) that may limit their effectiveness in children with MR. 

Theories about the causes of mental disease are just that - theories. Various areas of the brain are involved in integrating "normal" behaviour patterns. DA, NE and 5-HT are believed to be key neurotransmitters in these systems. An overactivity in dopaminergic or adrenergic neurons may bring on a hyperagitated state. The neuroleptics were introduced into treatment in... 

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