CHRONIC FORCED SWIM STRESS OF RATS INCREASES FRONTAL CORTICAL 5-HT2 RECEPTORS AND THE WET-DOG SHAKES THEY MEDIATE, BUT NOT FRONTAL CORTICALBETA-ADRENOCEPTORS

We studied the effects of chronic forced swim stress on 5-HT2 receptor s and beta-adrenoceptors in the rat frontal cortex. The number of 5-HT 2 receptors was increased immediately after the last chronic stress, b ut not after an acute stress. In vivo, the number of wet-dog shakes in duced by a 5-HT2 receptor agonist, +/-)-1-(2,5-dimethoxy-4-iodophenyl) -2-aminopropane (DOI), was increased 24 h after the last chronic stres s. However, the concentrations of 5-HT and 5-hydroxyindole acetic acid (5-HIAA), measured by high pressure liquid chromatography (HPLC), wer e not altered by this stress. Binding sites for [H-3]CGP-12177, i.e., beta-adrenoceptor sites, were unchanged after both the acute and the c hronic stress. These results suggest that, in the rat, the chronic for ced swim stress increases the number of frontal cortical 5-HT2 recepto rs and the number of wet-dog shakes mediated by these receptors, while the number of frontal cortical beta-adrenoceptors is not increased by this treatment.