[Mechanisms of realization of stimulating effects of serotonin on immune processes]

Low dosages of serotonin and 5-hydroxytryptophan were found to stimulate rosette-forming process in spleens of male CBA mice (5 X 10(6)) immunized with sheep red blood cells, in contrast to high dosages that are known to induce inhibition. The above finding suggests a bimodality of serotoninergic immunomodulation. Immune responses were compared between shamoperated, adrenalectomized, thymectomized mice and mice with lesion of hypothalamo-pituitary complex (the destruction of pituitary or its stalk). It was shown, that neither hypothalamo-pituitary-adrenal system by means of which the inhibitory effect of serotonin (high dose) was released, no thymus, where the increase of rosette-forming process was released in adrenalectomized mice which obtained high doses of serotonin. The dosage-response curve suggests mediating of opposite serotonin effects via serotonin reactive structures with different serotonin sensitivity.