Stereological Study of Number of Follicles and Mean Follicular Diameters of Spleen Following L-NAME Administration in Pregnant Rat

Background: Nitric oxide is involved in many physiological functions of the body. And its important roles in biological process is still the matter of investigation. Nitric oxide is synthesized from the amino acid L-arginine by NO synthase in the presence of oxygen and NADHP (Nicotinamide Adenine Dinucleotide Phosphate). It has been recognized that NO has many protective roles in the immune system as well as cytotoxic effects. The present study was conducted to investigate the stereological changes of white pulp of spleen in pregnant rats following L-NAME administration as a NO synthase inhibitor. Methods: Twenty four female Sprague Dawley rats of 8 weeks old and 200-250 gr weight were selected. They were divided into three groups including 8 rats in each group after mating and observing vaginal plaque. All groups except the control group received 2 ml/Kg saline and 20 mg/Kg L-NAME intraperitoneally on days 3rd, 4th and 5th of pregnancy. On the 18th day of pregnancy, the rats were  sacrificed and their spleen were removed. The spleen were fixed in 10% formalin and sections were stained with H&E. Quantitative measurement such as the number and mean diameter of white pulps were performed through light microscopy and Image tools III software. Results: In the L-NAME group we found no statistical significant in the mean diameters of white pulp in comparison with control and saline groups. However, the number of white pulps were decreased in L-NAME group which statistically was significant (P<0.05). Conclusion: We conclude that the L-NAME as NO synthase inhibitor could decrease the number of white pulps in spleen of pregnant rats.