Nitric Oxide: A Prime Signaling Molecule in Bovine Male Reproduction
R. A. Siddique Shabana N. Ali M. K. Bharti Ajit Kumar Anand Kumar T. Ambwani
Nitric oxide (NO•) is an important bioactive molecule with a short half-life. It is synthesized from the enzymatic conversion of L-Arg to L-citrulline in presence of nitric oxide synthases (NOS) and cofactors. The level of NO• is very important as it shows beneficial effects at lower concentration whereas cytotoxic at higher concentration. It acts as protective agent and maintains post thaw motility and viability of spematozoa. NO• plays critical importance in penile erection by relaxing the smooth muscle via inhibiting Rho A/ Rho-kinase pathway. It also participates in spermatogenesis, capacitation and acrosome reaction via cAMP/ cGMP pathways in mammals. Systemic inhibition of NOS caused impaired copulation, decreased erections and alteration in aggressive behaviour. Inhibition of cNOS significantly reduced the invitro fertilization, sperm-zona pellucida binding and proper embryonic development. Therefore, the cross talk and multiple systems induced by NO• act parallelly, safeguard the timely function of the spermatozoa responsible for fertilization.
Keywords : Aggression Capacitation and Acrosome Reaction Erectile Dysfunction Mating Behaviour Nitric Oxide Signaling Event Spermatozoa Protective Action
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