The role of nitric oxide in reproduction

Nitric oxide (NO) plays a crucial role in reproduction at every level in th e organism. In the brain. it activates the release of luteinizing hormone-r eleasing hormone (LHRH), The axons of the LHRH neurons project to the matin g centers in the brain stem and by afferent pathways evoke the lordosis ref lex in female rats. In males, there is activation of NOergic terminals that release NO in the corpora cavernosa penis to induce erection by generation of cyclic guanosine monophosphate (cGMP). NO also activates the release of LHRH which reaches the pituitary and activates the release of gonadotropin s by activating neural NO synthase (nNOS) in the pituitary gland. In the go nad, NO plays an important role in inducing ovulation and in causing luteol ysis, whereas in the reproductive tract, it relaxes uterine muscle via cGMP and constricts it via prostaglandins (PG).