INHIBITION OF REGENERATION BY MELATONIN IN NEMERTEAN WORMS OF THE GENUS LINEUS

Melatonin is a molecule mainly produced by the pineal gland in vertebr ates but is also present in invertebrates. For example, melatonin endo genous to Lineus lacteus Montagu, 1804 has been demonstrated in the he ad region. Different pieces of Lineus lacteus and Lineus sanguineus (R athke, 1799) have been maintained for regeneration in solutions of mel atonin (25 and 50 mg/l approximate to 0.11 and 0.22 mmol/l). In such c ases, regeneration is either retarded or does not occur at all. Our wo rk supports a hypothesis dealing with the inhibitory effect of exogeno us melatonin on the regeneration of these two species.