Quantitative analysis of nitric oxide synthase expressed in developing and differentiating rat cerebellum

In order to investigate quantitatively the differentiation and maturation process of granule cells in the postnatal development of rat cerebellum, nitric oxide synthase (NOS) activities were determined in the micro-dissected developing cerebellar layers, using our microassay method. NOS activities were increased in the molecular and internal granular layers (IGLs) during development and the activity was measurable in the neuroblastic external granular layers (EGLs). Newly devised micro-immunoblot analysis semi-quantitatively showed more amount of endothelial NOS (eNOS) and non-negligible amount of neuronal NOS (nNOS) in microsamples from EGL, compared with other developing and adult cerebellar layers. nNOS mRNA was also detected using RT-PCR (reverse transcriptase-polymerase chain reaction) in the microsamples from this germinal layer. Intraperitoneal administration of NG-nitro-l-arginine inhibited NOS activity in vivo and disturbed the layer formation in developing cerebellum.