The stimulating influence of the raphé nuclei on the morphofunctional development of the hippocampus during their combined cultivation

Abstract

It has been demonstrated in combined (raphé nuclei-hippocampus, cerebellum-hippocampus) organotypical cultures of the brain of newborn rats that, unlike cerebellar expiants, the raphé nuclei grow in an oriented manner toward the hippocampus and exert a stimulating influence on its morphofunctional development; this is manifested: a) in an intense proliferation and migration of glial cells, which are accompanied by accelerated growth of neuronal processes and an increase in the dimensions of the initial piece; b) in the earlier formation of the background electrical activity of the neurons; c) in an increase in these cultures in the number of active cells; d) in a significant predominance of neurons with periodic (in the form of trains or groups) discharges. These data are in agreement with previously established effects of exogenous serotonin, and attest to an important role of the serotoninergic influences of the raphé nuclei in the morphofunctional development of the hippocampus.