Neuronal and endothelial nitric oxide synthase isoforms: Quantification ofprotein and mRNA in the normal rat penis

Nitric oxide synthase (NOS) is an important enzyme for erection. We evaluat ed the content of neuronal (nNOS) and endothelial (eNOS) isoforms and their mRNA in the penis and major pelvic ganglion (MPG) of adult male rats by We stern and Northern blot analysis. The cerebellum was evaluated as a control . nNOS protein and its mRNA were detected in abundance in the MPG, cerebellum , pelvic urethra and within the crura of the penis. In contrast, the penile urethra, neurovascular bundle and the shaft of penis contained smaller amo unts of this protein. eNOS protein was most abundant in the penile and pelvic parts of the urethr a, whereas a moderate level was found in the penile shaft, crura, neurovasc ular bundle, MPG and cerebellum, Similarly eNOS mRNA was abundant in the pe nile and pelvic parts of the urethra, MPG and cerebellum. Penile shaft, cru ra and neurovascular bundle showed moderate amounts of eNOS mRNA. In conclusion, nNOS and its mRNA are most abundant in the MPG and crura of penis whereas eNOS is most abundant in the urethra and to a lesser extent p resent in the penis. Importantly eNOS protein and mRNA were demonstrated in the MPG, where eNOS function has to be studied.