LEVELS OF STIMULATORY G-PROTEIN ARE INCREASED IN THE RAT STRIATUM AFTER NEONATAL LESION OF DOPAMINE NEURONS

AFTER neonatal lesions of dopamine enhanced behavioural responsiveness agonists has been described, suggesting a D1 receptor hypersensitivit y. In the present study, unilateral striatal dopamine denervation in n ewborn rats induced a pronounced rotational behaviour following apomor phine injection at the adult age, without any change in the density of D1 binding sites in the denervated striatum. The amount of stimulator y G(olf)alpha subunit was increased by 35% in the lesioned striatum. T he large form and the short forms of G(s) alpha were also increased by 26% and 9%, respectively. Since in striatal neurones, the coupling of D1 receptor to adenylate cyclase is mostly provided by G(olf)alpha, o ur results strongly suggest that D1 hypersensitivity described after n eonatal dopamine lesions results from an increase in the levels of G(o lf)alpha protein.