Expression of eight metabotropic glutamate receptor subtypes during neuronal differentiation of P19 embryocarcinoma cells: a study by RT-PCR and in situ hybridization.

Metabotropic glutamate receptors modulate neuronal activity but expression and alternative splicing of their subtypes (mGluR1-mGluR8) during early neuronal differentiation are essentially unknown. In the mouse embryocarcinoma cell line P19, one of the best established systems to study neurogenesis in vitro, it was shown by RT-PCR and in situ hybridization that the neuronal differentiation process, induced by retinoic acid, is characterized by an early increase in the expression of mGluR3, mGluR7 and mGluR8 and a late rise in the mRNA levels of mGluR1 and mGluR5, whereas mGluR2 and mGluR4 seem to be constitutively expressed. In comparison, in primary embryonic neurons all mGluR subtypes were detected at day 3 after plating while primary astrocytes and oligodendrocytes have diverging mGluR pattern. In addition, the splicing pattern of mGluR1 and mGluR5 transcripts differ remarkably between neural cells in vitro and brain tissue. These data, although not comparable to the situation in vivo, might be a hint on so far unknown functions of metabotropic glutamate receptors during neuronal differentiation.