[Dependence of the effects of tripeptide MIF and lithium chloride on the degree of supersensitivity of dopamine receptors of the brain].

The desensitizing effects of MIF and lithium in respect to supersensitive striatal DA receptors in rats with unilateral lesion of the nigro-striatal pathway by 6-hydroxydopamine were revealed. Two groups of 6-hydroxydopamine-denervated rats were selected by their qualitative responsiveness to apomorphine-induced rotational behavior. It was found, that MIF and lithium (subchronic administration) did not modify behavioral supersensitivity in the highly sensitive group which showed two-peak rotational pattern in response to 0.05 mg/kg apomorphine, which was converted into a single-peak rotational pattern by haloperidol. On the contrary, administration of MIF and lithium for 21 days inhibited the apomorphine-induced rotations to 54 and 65% respectively in the less supersensitive group, which showed a single peak rotational pattern to apomorphine. Moreover, haloperidol showed the high antagonistic potency in these animals. These results suggest, that MIF and lithium might not exert desensitizing effects in the presence of high degree of supersensitivity of the striatal DA receptors, which is probably involved, for example, in the phenomenon of persistent tardive dyskinesia.