Neuroleptic-induced acute dystonic reactions may be due to enhanced dopamine release on to supersensitive postsynaptic receptors

Oral administration of butaperazine (40 mg per kilogram) to rats increased dopamine turnover, as measured by elevation of striatal and mesolimbic concentrations of homovanillic acid and 3,4-dihydroxyphenylacetic acid, for 24 to 48 hours. Initially, this dose of butaperazine inhibited stereotyped behavior in response to subcutaneous administration of apomorphine, but this effect was reversed at 12 hours. Later, animals had normal or exaggerated responses to apomorphine. The data suggest that the critical 20- to 28-hour period after butaperazine administration, when most human acute dystonic reactions occur, normal or supersensitive cerebral dopamine receptors are exposed to an excessive synaptic release of dopamine. This may be responsible for the drug-induced dystonia.     

Lesions of the globus pallidus,entopeduncular nucleus and substantia nigra alter dopamine mediated circling behaviour

Experimental Brain Research - Unilateral kainic acid lesions of the globus pallidus in the rat caused weak spontaneous circling at 3 and 10 days after surgery. Unilateral kainic acid lesions of the...     

Influence of age on isolation stress-stimulated carcinogen-metabolizing enzymes of rats

Rats aged 6, 12, 24, 36, and 52 weeks were subjected to social isolation for 4 days, while littermates housed in groups of six for the same period served as controls. The isolation treatment resulted in a 2-fold increase in the serum corticosterone level of all except the youngest animals in whom the hormone level was greater than 4 times that of their age-matched controls. Hepatic microsomal protein was highest in the 24-week-old rats and lowest in the rats aged 52 weeks. The levels of most of the enzymes measured were lowest in the 6- and 52-week-old animals. No significant differences in microsomal protein, cytochrome P₄₅₀, epoxide hydrolase, UDPGA transferase, or glutathione transferase were observed between the isolated and control animals. The stress treatment increased aryl hydrocarbon hydroxylase levels of the rats aged 6, 36, and 52 weeks by 100%, 50%, and 33% respectively. The microsomes prepared from livers of isolated 6-week-old animals catalyzed the binding of significantly higher amounts of [³H]-benzo(a)pyrene to DNA than controls.