5-HT2A receptor activation leads to increased BDNF mRNA expression in C6 glioma cells.

It has recently been suggested that an increase in brain-derived neurotrophic factor (BDNF) expression may mediate some of the therapeutic effect of antidepressant drugs, via their effects on the neurotransmitter 5-hydroxytryptamine (5-HT). However, because it is unclear whether 5-HT manipulations directly affect BDNF expression, we examined BDNF mRNA levels in C6 glioma cells following incubation with 5-HT using reverse transcription polymerase chain reaction (RT-PCR) and Northern blot analysis. Incubation of C6 glioma cells with 5-HT increased the BDNF mRNA expression approx twofold. The effect of 5-HT (100 microM) was inhibited by a 5-HT2A receptor antagonist (ketanserin; 1 microM). The RNA synthesis inhibitor (actinomycin D; 10 microg/mL), but not a protein synthesis inhibitor (cycloheximide; 0.5 microg/mL) blocked the effect of 5-HT. Furthermore, incubation of C6 glioma cells with EGTA (1 mM), a protein kinase inhibitor (staurosporine; 1 microM), the Ca2+ ATPase inhibitor thapsigargin (1 microM), or a calcium/calmodulin-dependent kinase inhibitor (KN 62; 1 microM) inhibited the response to 5-HT. Our data show that 5-HT increases de novo BDNF mRNA synthesis following direct activation of the 5-HT2A receptor, via a calcium-dependent and protein kinase-dependent pathway.