Changes in the concentrations of steroids and prostaglandin F in preovulatory follicles of the mare after administration of hCG.

This research studied the effects of injecting hCG (human chorionic gonadotropin) on hormone levels inside a horse’s maturing ovarian follicle. It found that hCG increases progesterone and testosterone levels but does not impact oestradiol and prostaglandin F levels.

Experimental Procedure

• The researchers group mares into three distinct groups.
• The first group (Group 1 mares), fluid was taken from the preovulatory follicle when they reached a particular size (32-34 mm).
• The second group (Group 2 mares) received an intravenous injection of hCG when the preovulatory follicle reached a larger size (35 mm). This group’s follicular fluids were aspired 28-32 hours after the hCG treatment.
• For the third group (Group 3 mares), the follicular fluid was aspired 28 to 32 hours after the preovulatory follicle reached the 35 mm size, but this group did not receive any hCG treatment.

Research Findings

• The study found that the concentration of progesterone was significantly higher in the follicular fluid from Group 2 mares (i.e., those that had received the hCG injection).
• Similarly, testosterone levels were significantly higher in follicular fluid from both hCG-treated mares (Group 2) and the mares whose follicular fluid was aspired at a larger size without hCG treatment (Group 3) compared to Group 1 mares.
• However, there were no significant differences in concentrations of oestradiol and prostaglandin F (PGF) among the three groups.

This indicates that hCG may influence progesterone and testosterone levels in the preovulatory follicles but does not appear to significantly impact concentrations of oestradiol and prostaglandin F.