Pituitary and gonadal response to GnRH in prepubertal buffaloes (Bubalus bubalis)

The objective of this study was to investigate the responsiveness of hypophysis and gonads to synthetic GnRH among prepubertal buffalo heifers at 12 months of age. Peripheral plasma FSH, LH, estradiol and progesterone level were measured in blood samples collected at 1 hr before and up to 18 days subsequent to the administration of 200 mu g GnRH (n=6) or saline (n=6) in Murrah buffalo heifers. The pretreatment peripheral plasma FSH, LH, estradiol and progesterone among GnRH treated heifers were 7.35 +/- 0.45 ng/ml, 1.08 +/- 0.3 ng/ml, 22.93 +/- 1.06 pg/ml and 0.27 +/- 0.04 ng/ml respectively. A quick elevation (p < 0.01) of FSH and LH within five min of GnRH administration was observed in all heifers. Although the peak FSH (89.57 +/- 23.43 ng/ml) and LH (7.52 +/- 3.08 ng/ml) reached by 10 min of GnRH administration, yet the animals differed both in terms of their amplitude response of FSH and LH release as well as in terms of time which animals took to exhibit maximum response to GnRH administration. The GnRH administration did not cause alteration in plasma estradiol and progesterone level. The present study suggests that the pituitary of 12 month buffalo heifers has capacity to synthesize and store of gonadotropin and have developed receptors for GnRH for a spike of gonadotropin release.