Expression of constitutive nitric oxide synthase in a primary neuronal culture.

Nitric oxide (NO), a short-lived, highly diffusible free radical, is a messenger molecule produced through the conversion of arginine to citrulline by NO synthase (NOS). In the CNS, NO functions as an important neuromodulator. We now report that cerebellar granule cells in culture express the constitutive form of NOS (cNOS). The expression is demonstrated both at the level of RNA, by RNA-specific reverse transcription-polymerase chain reaction (RT-PCR), and of protein, by immunostaining and by enzymatic activity. Cerebellar granule cells can thus serve as a tool to study the regulation of expression and activity of cNOS in a defined environment.