Antidepressants reverse the olfactory bulbectomy-induced decreases in splenic peripheral-type benzodiazepine receptors in rats.

The present study investigated the effects of 21-day administration of clorgyline (1 mg/kg/day), desipramine (10 mg/kg/day) or paroxetine (10 mg/kg/day) on peripheral-type benzodiazepine receptors in rat peripheral tissues following bilateral olfactory bulbectomy. Thymus and spleen weights decreased as a result of bulbectomy. Subsequent antidepressant drug administration had no further effects on the weights of thymus glands but increased those of spleens. In thymus glands, higher densities of peripheral-type benzodiazepine receptors were observed in medulla than in cortex; no significant variations were observed following bulbectomy or antidepressant drug administration. In spleen, higher densities were observed in white pulp than in red pulp. The bulbectomy-induced decreases in binding densities observed in both regions were reversed following administration of antidepressants. Adrenal peripheral-type benzodiazepine receptors were not altered by bulbectomy or subsequent treatment with clorgyline or desipramine while paroxetine upregulated these receptors. No changes in kidney peripheral-type benzodiazepine receptors were observed. The present study confirms that cell lines of the rat immune system possess high densities of peripheral-type benzodiazepine receptor binding sites and further support the contention that, following olfactory bulbectomy, rats may present an antidepressant-reversible immunitary dysfunction.