Leptin, Insulin Like growth factor-I, Nitric oxide, thyroid and ovarian hormones in serum of early pregnant and cyclic Arab mares with or without clinical endometritis

This study hypothesize that some metabolic hormones increase during clinical endometritis and modulate immune responses to combat this inflammation in mares. 45 mares of different ages were used. Mares were examined by ultrasound and underwent weekly blood sampling from the day of estrus detection till determination of early pregnancy. Mares were classified according ultrasound examination into early pregnant mares (N=16), non-lactating during estrus (N=17), clinical endometritis (N=3) and lactating during foal heat (N=9). Blood serum leptin, IGF-I, T3, T4, estradiol, progesterone, testosterone were assayed using commercial ELISA kits. Copper, zinc and iron was measured using Atomic Flame absorption spectrophotometer. Nitric oxide (NO) was measured calorimetrically using spectrophotometer. Results of this study showed that mares with endometritis days 7-14 after ovulation had significantly high IGF-I (P=0.0001) and T4 (P=0.009), low progesterone (P=0.0001) and NO (P=0.18) compared to those cyclic without clinical endometritis or early pregnant mares and insignificantly (P=0.74) slight increase in leptin. A direct significant (P < 0.05) correlation existed between IGF-I and NO (P=0.02), between IGF-1 and T4 (P=0.05) and between leptin and testosterone (P < 0.05) but an inverse relation existed between T4 and Estradiol (P < 0.01) and Estradiol and testosterone (P < 0.01). Inverse non significant (P > 0.05) correlations existed between NO and leptin. This study proved our assumption that leptin, IGF-I and thyroxin increase during mare endometritis to combat inflammation beside their physiological role during estrus, ovulation, and early pregnancy.