IDENTIFICATION OF 5-HT RECEPTOR SUBTYPES IN A HOMOGENEOUS POPULATION OF PRESUMPTIVE SEROTONINERGIC NEURONS

The expression of the known rat 5-HT receptor sub-types has been analy zed in a presumptive serotoninergic cell line derived from the rat rap he nuclei, using reverse transcription followed by polymerase chain re action. By manipulating the activity of the oncogene (ts-SV40T) produc t used to immortalize the serotoninergic precursors, it has been possi ble to compare the expression of the 5-HT receptors in either replicat ive or differentiating cells. 5-HT1B, 5-HT1D, 5-HT3, 5-HT6 and 5-HT7 r eceptor gene expression were all observed in the replicating cells. Ho wever, under differentiation conditions, expression of all except the 5-HT1B receptor was lost. Only one novel amplification product appeare d during early differentiation, in the 5-HT2B lane; its smaller than e xpected size was suggestive of a previously undescribed alternate spli cing of the mRNA in brain. The curtailment of 5-HT receptor expression in differentiating neurones in vitro may reflect the normal ongoing r estriction in the phenotypic potential during embryogenesis in vivo. T he serotonin cells, therefore, constitute a pristine cell line in whic h to study the receptor pharmacology of one or more 5-HT receptor sub- types in isolation. (C) 1997 Elsveier Science Ltd.