ABSTRACT
Kisspeptin is a neuropeptide that governs the reproductive axis upstream to GnRH. We wanted to study whether kisspeptin modulates plasma LH and FSH levels and ovarian follicular dynamics in buffaloes and whether kisspeptin can be used for fixed time artificial insemination (FTAI). We carried out these studies in comparison with buserelin, a potent GnRH agonist. Kisspeptin dose-dependently increased plasma LH levels. However, the kisspeptin-induced increase in LH was short-lived as the peak reached in 15-30 min returned to basal values by 1-2 h. The kisspeptin-induced increase in LH level was less compared to buserelin-induced increase in LH level which sustained over time. Kisspeptin did not enhance FSH release while buserelin resulted in a gradual increase over time. LH response to repeated injections of kisspeptin was greater than that induced by buserelin. While buserelin induced an increase in the number of follicles, kisspeptin induced an increase in the growth rate of the follicle. In adult cycling animals, while both the drugs increased plasma LH levels, the increase was greater in buserelin group compared to kisspeptin group. In contrast to the findings in pre-pubertal animals, kisspeptin induced an increase in both the number as well as the size of follicles compared to buserelin. Our studies on oestrus synchronization, using either kisspeptin-PGF2α-kisspeptin protocol or buserelin-PGF2α-buserelin Ovsynch protocol on day 0, 7, and 9, respectively, revealed that kisspeptin increased the number of follicles at wave emergence and the diameter of dominant follicle after 2nd dose of drug, the oestrus response rate and duration of oestrus, compared to buserelin. However, conception rate was not significantly different among the groups. From our studies, it appears that Kp and Buserelin differentially modulate follicular dynamics depending on the reproductive age of the animals.However, studies in a larger herd are required to confirm whether kisspeptin can be used for oestrous synchronization in buffaloes.
ABSTRACT
AIM: The aim of this study was to investigate the effect of kisspeptin (KP) on in vitro maturation (IVM) of sheep oocytes aspirated from the ovaries collected from slaughterhouse. MATERIALS AND METHODS: Two different experiments were conducted to investigate the effect of KP (5, 10 and 15 µg/ml) alone (experiment 1) or in combination with follicle-stimulating hormone (FSH), luteinizing hormone (LH), and Estradiol (E2) (experiment 2) on IVM of sheep oocytes. Tissue culture medium 199 supplemented with Gentamicin was used as control medium. Good quality oocytes were randomly allocated into different IVM media and cultured at 38.5°C in 5% CO2 under humidified atmosphere for 24 h. The oocytes were evaluated for their cumulus cell expansion (CCE) and extrusion of the 1st polar body (PB) at the end of maturation. RESULTS: The proportion of oocytes showing CCE and extrusion of PB was highest when the oocytes were matured in the medium supplemented with 10 µg/ml of KP. In experiment 2, oocytes were matured in 12 different maturation media (G1-G12: G1: Control, G2: KP alone, G3: FSH, G4: FSH+KP, G5: LH, G6: LH+KP, G7: E2, G8: E2+KP, G9: FSH+LH+E2, G10: FSH+LH+E2+KP, G11: FSH+LH+E2+fetal bovine serum (FBS), G12: FSH+LH+E2+FBS+KP). The proportion of oocytes showing cumulus expansion and PB extrusion was highest (98.33±1.05 and 89.17±2.38) when they were matured in FSH+LH+E2+FBS+KP (G12) and was significantly higher than other groups. The proportion of CCE and extrusion of PB was significantly increased when KP was supplemented to FSH and E2, but no effect was observed with LH. The maturation rates were significantly increased when FSH, LH, and E2 (G9) containing media were additionally supplemented with KP (G10). CONCLUSION: This study demonstrated that the addition of KP (10 µg/ml) to the FSH, LH, and E2 supplemented media would enhance the sheep oocyte maturation in vitro.