Is uterine blood flow influenced by hCG and mare age?

The research paper investigates whether human chorionic gonadotropin (hCG) and the age of a mare influence uterine blood flow. The study found that administering pre-ovulatory hCG did not have significant effects on uterine artery blood flow, or concentrations of estradiol in serum or follicular fluid. It also suggested that the uterine artery resistance index might decrease in young mares after ovulation due to an increase in uterine perfusion.

Research Methodology

• The scientists selected 27 Arabian mares and divided them into two age groups: ‘young’ (ages 3 to 10) and ‘old’ (ages 19 to 23).
• Doppler ultrasonography was used to examine the uterine arteries when an ovarian follicle was visible. This technique is noninvasive and allows for the observation of physiological and pathophysiological changes in tissue blood flow. It is becoming increasingly important in veterinary medicine.
• After initial measurements, 14 mares, chosen at random, were given human chorionic gonadotropin (hCG).
• Doppler ultrasonography was repeated the following day, and dominant follicles were aspirated to collect follicular fluid in all the mares.
• On the third day, Doppler indices of the uterine artery blood flow were measured again.
• Additionally, blood samples were taken prior to each ultrasonography session to measure serum estradiol and progesterone levels.

Research Findings

• Results showed that hCG administration prior to ovulation did not have any substantial effects on the uterine artery blood flow or the concentration of estradiol in serum or follicular fluid.
• The research also demonstrated that in younger mares, the resistance index of the uterine artery might decrease post-ovulation, potentially indicating a rise in uterine perfusion.

Implications of the Research

• The study helps enhance understanding of the reproductive physiology of horses, particularly in relation to how hormones and age affect uterine blood flow during ovulation.
• These findings could potentially improve breeding strategies and veterinary care for horses, although no direct influence from hCG was found in this study.
• The possible increase in uterine perfusion in younger mares following ovulation offers new avenues for research into age-related changes in the reproductive system of horses.