Effect of nitric oxide synthase inhabitors on ovulation in hCG-stimulated mares.

This study investigates the role of nitric oxide in the process of ovulation in mares and whether blocking the production of nitric oxide by using specific inhibitors affects the timing of ovulation, indicating a regulatory role of nitric oxide in reproductive processes.

Introduction

• Nitric Oxide (NO) is a chemical compound that has been observed to have potential regulatory impacts on the functioning of the ovaries.
• The aim of this study is to understand the role of NO in the ovulation process in mares, which are female horses, by using inhibitors to block the production of NO.

Methodology

• The study used forty cycling mares, which were split into three different treatment groups.
• These different groups were given either a simple saline solution, a known NO production inhibitor (Nomega-nitro-L-arginine methyl ester hydrochloride, or L-NAME), or a second NO production inhibitor (aminoguanidine hemisulfate, or AG).
• The treatments were applied once a follicle of a certain size (between 27 and 35mm in diameter) was detected in the mares.
• Ovulation was then stimulated through the administration of human Chorionic Gonadotropin (hCG).

Results

• The study found a significant variation in the median ovulation times for the different treatment groups.
• Mares treated with the saline solution had a median ovulation time of 42 hours, while those treated with L-NAME and AG had median ovulation times of 84 and 54 hours respectively.
• There was no significant difference between the ovulation times for the groups treated with the NO inhibitors (L-NAME and AG).
• However, both these groups had significantly different ovulation times from the control group, which received the saline solution.

Conclusion

• The researchers concluded that the delay in ovulation observed in the mares treated with the NO inhibitor suggests that NO plays a significant role in follicular development and ovulation in horses.