The Effect of Sildenafil on Mouse Oocyte Development in Vivo - Literature review Example

Although there has been remarkable progress in the field of assisted reproduction technology (ART) since 1978, pregnancy rates have not yet reached the expected levels. Two of the most common problems in ART are poor ovarian response and implantation failure after ovarian stimulation and embryo transfer respectively. The use of Viagra for recreational use is well documented, and the drug is widely used by men to treat erectile dysfunction.

However, prolonged use by men could cause infertility. In research by David Glenn, who works with the Queen's University, Belfast, Glenn took samples of sperm from volunteers and bathed them in weak solutions of sildenafil citrate, to produce a dosage, equal to that found in the blood of a male who had consumed a tablet of the drug. The behavior of the treated sperm was compared with another sample of untreated sperm. The findings indicate that sildenafil citrate increased the activity level of the sperms, but found that it damaged the acrosome of the sperm, which contains enzymes needed to dissolve the membrane of a woman's oocyte.

This meant that the acrosome breaks down early, and thus, it is not able to act on the woman's eggs, and fertilization does not take place (McKie, 2008). Sildenafil has been used with great success for the treatment of erectile problems in males since 1997 (Sher et al. 2000). The fact that NO synthase is present in the ovarian cells, the endometrium (Hattori and Tabata, 2006), and within the ovarian vascular network (Sher, et al. 2000) combined with the finding that its vasodilatory effects show a positive correlation to its concentration, oriented the researchers (Tamanini, et al., 2002) to use sildenafil as a treatment for hypertension and Intrauterine Growth Restriction (IUGR) during pregnancy (Sasser and Baylis, 2010).

Research by Neithardt et al. (2005) studied the process of the embryo after loading, by placing the catheter and a dose of sildenafil citrate, applied vaginally for 127 women who had difficulty in conceiving. After some time, the researchers found that the pregnancy rate of women with ET, was 52.4%, and at the same time, it was 34.9% for the group who were not administered the dose. The researchers, therefore, concluded that sildenafil citrate impacts the success of embryo transplant after loading.

In related research, Zinger et al. (2006) used sildenafil citrate to treat two infertile women, who suffered from the Ashermans syndrome. The women had a thin endometrium and had subsequently failed to conceive in previous IVF treatment.