>melatonin n [Gk melas black + -tonin (as in serotonin)] (1958) : >a vertebrate hormone of the pineal gland that produces lightening >of the skin by causing concentration of melanin in >pigment-containing cells Io non pote trovar isto o serotonin in mi varie dictionarios altere que le anglese. Io necessita dictionarios medic in iste altere linguas. Stan Mulaik