SEROTONIN DEPLETION BY 5,7-DIHYDROXYTRYPTAMINE DOES NOT AFFECT G-PROTEIN SUBUNIT LEVELS IN RAT CORTEX

To investigate the role of G proteins in denervation supersensitivity of the CNS serotonergic system, we examined the effect of lesioning se rotonergic neurons on the abundance of cerebral cortical membrane G pr otein subunits in rats. Three weeks after intracisternal injection of 5,7-dihydroxytryptamine (5,7-DHT), which significantly reduced cortica l 5-hydroxytryptamine (5-HT; similar to 90%) and 5-hydroxyindoleacetic acid (similar to 98%) levels, no statistically significant difference s were observed for G alpha(s-1), G alpha(s-s), G alpha(i1), G alpha(i 2), G alpha(q/11), G alpha(o), G(beta 1) and G(beta 2) immunoreactivit y levels between sham-lesioned and 5,7-DHT lesioned rats. These data s uggest that the functional supersensitivity of 5-HT neuronal system of ten observed following lesions of 5-HT fibers may not involve changes at the level of G proteins but may instead encompass other downstream elements of the 5-HT receptor signaling cascade.