The role of nitric oxide in reproduction

Abstract

Nitric oxide (NO) plays a crucial role in reproduction at every level in the organism. In the brain, it activates the release of luteinizing hormone-releasing hormone (LHRH). The axons of the LHRH neurons project to the mating centers in the brain stem and by afferent pathways evoke the lordosis reflex 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 gonadotropins by activating neural NO synthase (nNOS) in the pituitary gland. In the gonad, NO plays an important role in inducing ovulation and in causing luteolysis, whereas in the reproductive tract, it relaxes uterine muscle via cGMP and constricts it via prostaglandins (PG).

Effects of Neonatal Handling on Central Noradrenergic and Nitric Oxidergic Systems and Reproductive Parameters in Female Rats

“…The precise mechanisms by which estradiol stimulates the rapid increase in GnRH and LH remain unclear, but the participation of neurotransmitters in the control of the preovulatory GnRH and gonadotropin surges has been well established [for reviews, see [14, 15]]. This process appears to depend on both the positive-feedback actions of preovulatory estradiol secretion and specific neural signals to initiate the surge.…”

An agonist-induced switch in G protein coupling of the gonadotropin-releasing hormone receptor regulates pulsatile neuropeptide secretion

“…Although the dependence of GnRH secretion on [Ca 2ϩ ] i and its sensitivity to cAMP are well established, relatively little is known about the mechanism(s) that determine the pulsatility of GnRH neuronal secretion. The sparsely distributed GnRH neurons are known to be interconnected (9), and their release of GnRH at the median eminence has been proposed to be synchronized by nitric oxide (10,11).…”

Mısır-Soya Küspesi Diyetine Eklenen Guanidino Asetik Asitin Yumurta Tavuklarının Üretim Performansı, Kan Biyokimyasal Parametreleri ve Üreme Hormonlarına Etkisi

“…In the present study, it seems that GAA could not spare arginine and subsequently did not influence EP. Other status was that GAA addition to diet increases EP by increasing NO which subsequently increases reproductive hormones [12] and the hormones increase EP [15] . In the current study NO was not affected by dietary treatments and EP was not increased.…”

“…It is well known that nitric oxide releases gonadotropin-releasing hormone (GnRH) by activating pituitary nitric oxide synthase which finally influences FSH and LH hormones [12] . It can be found from Table 7 that nitric oxide was numerically higher in 0.114% GAA group, but the differences were not significant.…”

“…Earlier studies have shown the importance of arginine for nitric oxide and protein synthesis, growth and development in vertebrata [10,11] . Nitric oxide releases gonadotropinreleasing hormone (GnRH) by activating pituitary nitric oxide synthase which finally influences FSH and LH hormones [12] . Studies have indicated that FSH is involved in the recruitment of new follicles into the ovarian hierarchy and also the maturation and rapid growth of these new follicles [13,14] .…”