EFFECTS OF SUBCHRONIC ADMINISTRATION OF ANTIDEPRESSANTS AND ANXIOLYTICS ON LEVELS OF THE ALPHA-SUBUNITS OF G-PROTEINS IN THE RAT-BRAIN

The aim of this study was to examine the effects of subchronic adminis tration of psychoactive drugs on the alpha subunits of G proteins in t he rat brain, and also to determine if different classes of psychoacti ve drugs share a common property, i.e., of altering levels of these pr oteins. For this purpose, we selected the psychoactive drugs desiprami ne and phenelzine (antidepressants), lithium (antimanic), alprazolam a nd buspirone (anxiolytics), and metachlorophenylpiperazine (anxiogenic ). The levels of alpha subunits of G proteins (G(s), G(i1/2), G(q/11)) expressed in cortical, hippocampal, and cerebellar brain regions were studied by the Western blot technique. We observed that subchronic tr eatment with lithium significantly decreased, and with phenelzine sign ificantly increased levels of G(i1/2)alpha protein in the cortex and t he hippocampus. On the other hand, buspirone significantly decreased l evels of G(i1/2)alpha protein only in the cerebellum. Other psychoacti ve drugs, however, namely desipramine, meta-chlorophenylpiperazine, an d alprazolam, did not alter levels of G(s), G(i1/2), G(q/11)alpha prot eins in any of the brain regions studied. Since other studies have sho wn the involvement of G proteins in the mechanism of action of psychoa ctive drugs, our results demonstrate that expressed protein levels of the alpha subunit of G proteins are not altered by all the psychoactiv e drugs.