Comparative investigation of neuronal nitric oxide synthase immunoreactivity in rat and human claustrum.

ABSTRACT

We compared the distribution, density and morphological characteristics of nitric oxide synthase-immunoreactive (NOS-ir) neurons in the rat and human claustrum. These neurons were categorized by diameter into three main types large, medium and small. In the human claustrum, large neurons ranged from 26 to 40µm in diameter, medium neurons from 20 to 25µm and small neurons from 13 to 19µm. In the rat claustrum, large neurons ranged from 19 to 23µm in diameter, medium neurons from 15 to 18µm and small neurons from 10 to 14µm. The cell bodies of large and medium neurons varied broadly in shape - multipolar, elliptical, bipolar and irregular, consistent with a projection neuron phenotype. The small neurons were most seen as being oval or elliptical in shape, resembling an interneuron phenotype. Based on a quantitative comparison of their dendritic characteristics, the NOS-ir neurons of humans and rats displayed a statistically significant difference.