Neuronal nitric oxide synthase (nNOS) participates in diverse biological processes,such as neurotransmission,neuroendocrine physiology,the regulation of body fluid homeostasis and so on.Acetylation of transcription-related factors,a kind of epigenetic modification has been thought to be an important mechanism of gene expression regulation.It has been reported that the p300 acetyltransferase may acetylate the p50 subunit of NF-kappaB to regulate gene transcription.In the present study,the expression ofnNOS gene in rat glioma cell line C6 was found to be upregulated by Trichostain A (TSA,a histone deacetylase inhibitor,an activator of p300) in a concentration dependent manner by using real-time PCR.In functional analysis,an important p50 response elment was verified to locate within the nNOS promoter region by electrophoresis mobility shift assassy (EMSA).EMSA results also showed increasing of p50 binding to this element in nNOS promoter when induced by TSA.