ONTOGENIC DEVELOPMENT OF 5-HT1D RECEPTORS IN HUMAN BRAIN - AN AUTORADIOGRAPHIC STUDY

The pattern of pre- and postnatal appearance of 5-HT1D receptors throu ghout the different areas of the human brain was studied by quantitati ve in vitro autoradiography, using [I-125]GTI (serotonin O-carboxymeth yl-glycyl-[I-125]tyrosinamide) as a ligand. The anatomical distributio n of 5-HT1D receptors in neonatal, infant and children's brain was in good agreement with that observed in the adult, the basal ganglia and substantia nigra being the most intensely labelled areas. The developm ent of these receptors throughout the human brain was mainly postnatal : low densities of [I-125]GTI binding sites were observed at the fetal /neonatal stage in most regions analyzed, in contrast with the high le vels of labelling found in infant and children's brains. indeed, in a number of regions, including the globus pallidus, substantia nigra and visual cortex, a peak of overexpression of 5-HT1D receptors was obser ved in the first decade of life. Such overexpression could support a r egulatory role for 5-HT1D, receptors in advanced periods of the CNS de velopmental process. Our results also indicate that the administration of drugs acting on 5-HT1D receptors during the early postnatal period of life could result in modifications of their properties, as these r eceptors are already functional in this period.