Postnatal secretion of the subcommissural organ of the Meriones shawi: control of serotonin innervation

The postnatal development of the subcommissural organ (SCO) glycoprotein se cretion in form of Reissner's liber and the putative control of the seroton in innervation upon the SCO activity were examined by immunohistochemistry in the semi-desert rodent, Meriones shawi. Abundant SCO secretory material and numerous serotoninergic fibers reaching the SCO were observed in newbor ns meriones. An increase of both secretory material and serotonin fibres de nsity inside the SCO was observed during postnatal period and into adulthoo d. Neurotoxic destruction with 5,7-dihydroxytryptamine of the SCO serotonin input in the adult or the inhibition of serotonin synthesis by para-chloro phenylalanine at different postnatal ages, resulted in a decrease of the in tensity of SCO Reissner's fiber immunolabelling suggesting a reduction in t he SCO secretory material. This result might reflect either an inhibition o f the synthesis or a stimulation of release of secretory material. These da ta suggest that :serotonin innervation could be precociously involved in th e regulation of the merione SCO secretion. (C) 2001 Elsevier Science B.V. A ll rights reserved.