BRAIN-DERIVED neurotrophic factor (BDNF) enhances survival and protects dopaminergic neurons from neurotoxicity. We have examined in primary cultures of fetal mesencephalic neurons the expression of BDNF transcripts and its regulation by glutamate receptor agonists. RT-PCR experiments showed in these cultures the expression of mRNA encoding for neurotrophin receptors TrkA, TrkB and TrkC as well as a differential expression of alternative BDNF gene transcripts derived from exons 1a, 1b, 1c and 1d. In adult rat mesencephalon we only detected BDNF mRNAs originated from exons 1a and 1c. Quantitative RT-PCR analysis of mesencephalic neurons revealed that NMDA, but not kainate treatment, significantly increased BDNF mRNAs derived from exons 1b and 1d. Our data indicate the existence in mesencephalic neurons of different and alternative promoters within the BDNF gene that may be differentially regulated by glutamate receptor stimulation.