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

Melatonin is a molecule mainly produced by the pineal gland in vertebrates but is also present in invertebrates. For example, melatonin endogenous to Lineus lacteus Montagu, 1804 has been demonstrated in the head region. Different pieces of Lineus lacteus and Lineus sanguineus (Rathke, 1799) have been maintained for regeneration in solutions of melatonin (25 and 50 mg/l approximate to 0.11 and 0.22 mmol/l). In such cases, regeneration is either retarded or does not occur at all. Our work supports a hypothesis dealing with the inhibitory effect of exogenous melatonin on the regeneration of these two species.