Responsiveness of the cheetah (Acinonyx jubatus) ovary to exogenous gonadotropins after preemptive oral progestin treatment

Abstract

Control of ovarian function in cheetahs is sub-optimal, which currently limits the integration of assisted reproductive techniques into the genetic management of that endangered species. The objective of this study was to determine the effect of preemptive progestin treatment on the quality of ovarian responses after exogenous gonadotropin stimulation in cheetahs. Adult females received either 1) 200 IU equine chorionic gonadotropin (eCG) followed with 3,000 IU porcine luteinizing hormone (pLH) (intramuscular route) (n = 5; control group) or 2) similar eCG/pLH administration preceded by a 7-day treatment with oral progestin (0.1 mg/kg altrenogest; ALT group; n = 7). At 42 h post-pLH administration, a series of metrics was assessed via laparoscopy (number of follicles ≥ 2 mm, number of corpora lutea, oviduct and uterine cornua diameter and overall vascularization). Concentrations of fecal estradiol, progesterone and glucocorticoid metabolites (FEM, FPM, and FGM, respectively) were measured by enzyme immunoassay for 3 wk before ALT treatment (Period 1), 7 d during ovarian suppression period (Period 2), throughout eCG/LH treatment and laparoscopy (Period 3), and 6 wk following laparoscopy (Period 4). Overall, nine out of 12 cheetahs (4/5 in control and 5/7 ALT group) had freshly-formed corpora lutea at the time of laparoscopy. Mean follicle and corpora lutea numbers in the control versus ALT group were not different (P > 0.05). Overall measurements and vascularization scores also did not differ (P > 0.05) among groups. FEM average concentrations increased (P ≤ 0.05) in response to eCG for the ALT-treated females between Periods 2 and 3 and were sustained during Period 4. However, FEM average concentrations did not vary (P > 0.05) for control females throughout Periods 1–4. Post-ovulatory FPM average concentrations (Period 4) did not differ (P > 0.05) between the ALT-treated females and controls. FPM average concentration from both groups increased in Period 4 compared to Periods 1–3 (P ≤ 0.05). Females receiving the ALT treatment also had lower (P ≤ 0.05) FGM metabolite average concentrations than control females during ovarian suppression (suggesting adrenal suppression). Collective results suggest that ovarian response to gonadotropin treatment in the cheetah was improved following oral progestin administration due to the normative increase in estradiol following stimulation for these females compared with control. This treatment should lead to more effective timed assisted reproduction procedures for this species.