TISSUE DISTRIBUTION OF MONOAMINE NEUROTRANSMITTERS IN NORMAL AND REGENERATING ARMS OF THE FEATHER STAR ANTEDON MEDITERRANEA

Crinoid echinoderms can completely and rapidly regenerate arms lost fo llowing self-induced or traumatic amputation. Arm regeneration in thes e animals therefore provides a valuable experimental model for studyin g all aspects of regenerative processes, particularly with respect to the nervous system and its specific contribution to regenerative pheno mena. Taking into account the primary role of the nervous system in re generation in other invertebrates, we have investigated the specific i nvolvement of neural factors, viz. the monoamine neurotransmitters dop amine and serotonin, in arm regeneration of Antedon mediterranea. In t he present work, the presence of classical monoamines has been reveale d by employing specific immunocytochemical and histofluorescence tests in association with biochemical detection by means of high pressure l iquid chromatography. The distribution pattern of these neurohumoral m olecules at standard regenerative stages has been compared with that o f normal non-regenerating arms. Results indicate that both dopamine an d serotonin dramatically change in both their distribution and concent ration during the repair and regenerative processes. Their remarkably enhanced pattern during regeneration and widespread presence at the le vel of both nervous and non-nervous tissues indicates that they are im portant neural growth-promoting factors in crinoid arm regeneration.