Haloperidol treatment selectively affects expression of Galpha(i)3 subunit mRNA in specific regions of the rat brain

Relative abundance of GTP binding protein mRNA coding for subunits alpha(i)1, alpha(i)2 and alpha(i)3, and their changes induced with chronic blockade of D2 receptor by haloperidol were compared in the frontal cortex, striatum, hippocampus and cerebellar cortex of the rat using a specific method based on multiplex RT-PCR. Galpha(i) subtype 2 mRNA was the most abundant, followed by subtype 1 and subtype 3. The haloperidol treatment produced an area specific increase in Galpha(i)3 mRNA in the frontal cortex and a decrease of Galpha(i)3 in the striatum. After 8-day withdrawal period, haloperidol-induced,changes disappeared in the striatum but became accentuated in the frontal cortex. Changes in the relative expression of Galpha(i) subtypes may significantly influence long-lasting effects of chronic D2 receptor blockade.