CHANGES IN NEUROTRANSMITTERS IN SUPERIOR COLLICULUS AFTER NEONATAL ENUCLEATION - BIOCHEMICAL AND IMMUNOCYTOCHEMICAL STUDIES

The turnover rate of dopamine and serotonin and the level of glutamate in superior colliculus are increased in adult, neonatally enucleated rats compared with normal control adult animals. Moreover, immunocytoc hemical data showed that the stratum zonale and the stratum griseum su perficiale of the superior colliculus, specifically of bienucleated ra ts, display a dense network of serotonin-immunoreactive fibres, sugges ting an increase in serotoninergic innervation. At the electron micros cope level, serotonin-immunoreactive fibres and large postsynaptic ser otonin-immunoreactive profiles exhibiting microtubules could be observ ed in the stratum zonale and the stratum griseum superficiale of the b ienucleated rat. These results suggest that neonatal enucleation produ ces reorganization of serotoninergic and glutamatergic inputs. It is p ossible that serotonin may exert a profound influence upon collicular function.