Localization of nitric oxide synthase positive neurons in periaqueductal gray and raphe nuclear complex in rat

Densely NOS-positive neuronal cell bodies and fibers were mainly distributed in the dorsolateral subdivision at the rostral level, ventrolateral subdivision at the middle or caudal level of PAG. In addition, densely NOS-positive neuronal cell bodies and fibers were also detected in nucleus raphe dorsalis and nucleus linearis. Moderate density of NOS-positive neuronal cell bodies and fibers were localized in nucleus raphe median and nucleus raphe obscurus. Sparsely NOS-positive neuronal cell bodies were occasionally seen in the nucleus raphe magnus.