The nitric oxide synthase expression of rat cortical and hippocampal neurons changes after early lead exposure

The effect of lead exposure in nitric oxide synthase containing neurons (nNOS) within rat cortex and hippocampus was studied. Lead administration (1 g% lead acetate in drinking water) was commenced prior to mating and continued until 30 postnatal (PN) days. Immunohistochemical studies using antibody to nNOS showed, after lead treatment at PN21-PN30, a reduction in neuronal size and optical density (OD) of nNOS+ cells. In both regions, non-pyramidal immunoreactive neurons exhibited smaller soma size and less developed dendrites. A significant difference in cell areas and OD of lead exposed versus control rats and no variation in the number of nNOS+ neurons was seen. Morphological modifications after early lead exposure, induced nNOS reduction in NOS expressing neurons thereby interfering in NO synthesis.