Expression and plasticity of NO synthase in the neuroendocrine system.

The expression of the nitric oxide (NO)-synthase enzyme (NOS) was analyzed in several hypothalamic nuclei and in the pituitary gland using in situ hybridization and immunohistochemistry. The effects of physiological and experimental stimuli on the expression of NOS was also investigated. Moreover, the role of NO in the secretion of anterior pituitary hormone luteinizing hormone (LH) was studied using primary culture of pituitary cells. The findings indicate that the expression of neuronal NOS is hormonally regulated and suggest that NO plays a role in hormone secretion.