Mouse models and the role of nitric oxide in reproduction

As a group, nitric oxide synthase (NOS) isoforms are localized to a wide variety of tissues. Understanding the role of NOS in reproductive physiology was facilitated by the introduction of genetically engineered mice. Specifically, "knock-out" mice with targeted disruptions in neuronal NOS, endothelial NOS and inducible NOS have been made. These models have been useful in addressing the of role of nitric oxide in areas of reproductive biology that include: hypothalamic-pituitary-ovarian axis, mating behavior, maternal blood pressure regulation and fetal development. Despite several promising observations using "knock-out" mouse models, one must exercise caution in interpreting data from individual experiments. Very often the need to draw on two mouse strains to generate the founder NOS deficient line, purity of the strain used for observing phenotypes (presence or absence of backcrossing to achieve a pure strain), and the strain used for comparison purposes (control strains are often not identical in their genetic make-up to the deficient line) make wide spread applicability of results open to criticism.