The aim of this study was to investigate the role
of Nitric Oxide (NO) in the atresia of ovarian follicles in an animal
model. Twenty adult, female rats (90 days old with body weights of 210 ± 10
g in the beginning of the experiments) were divided into 4 groups of 5
each. They were treated twice daily from the subcutaneous route for 21
successive days with either of the following chemicals: nitroglycerine,
L-arginine, L-NAME, or saline. On day 22, all animals were sacrificed.
Ovaries were dissected out free of connected tissue and were fixed in
formaline 10%. Later, paraffine blocks were prepared and serial sections
were made by means of H and E routine staining method. Intact and atretic
follicles were counted separately. In addition, damages were analyzed
qualitatively from the points of view of appearance and morphologic changes.
In the evaluation of ovarian follicular structures, different types of
healthy as well as atretic follicles were observed. In most of atretic
follicles, the oocytes were abnormally elongated and increnation of their
outlines were obvious. There were numerous macrophages around and inside
of the atretic follicles. Our investigation regarding the distribution
of atretic follicles in the ovaries of test groups revealed that atretic
follicles in the L-NAME treated group were increased in comparison to
the control group. Conversely, however, in the arginine-treated group,
the atretic follicles were reduced compared to the control animals. Treatment
with nitroglycerine of the rats decreased the number of atretic follicles
significantly (p<0.05) in comparison to the control group. In conclusion,
enhanced NO, either from endogenous or exogenous origins, prevents atresia
phenomenon, while inhibition of NO exerts an opposite effect.
Vahid Najati, Minoo Ilkhanipour, Shahpar Salehi and Goudarz Sadeghi-Hashjin, 2008. Role of Nitric Oxide on the Generation of Atretic Follicles in the Rat Ovaries. Pakistan Journal of Biological Sciences, 11: 250-254.