Use of a combination of synthetic oral progesterone and prostaglandin F2-alpha for ovulation induction protocols in Chinchilla lanigera

CANTARELLI VERÓNICA INÉS; GABRIELA F. MASTROMONACO; PONZIO MARINA FLAVIA

Congreso; International Society of Wildlife Endocrinology Virtual Event 2021; 2021

Altrenogest is a synthetic oral progesterone agonist used in farm animals as pre-treatment for suppressingthe natural estrous cycle, thus mimicking an extended luteal phase for as long as the progestin isadministered. Because progesterone has an inhibitory effect on the release of LH, the rationale is toartificially maintain an elevated concentration of progesterone until the corpora lutea regresses. Followingwithdrawal, estrus and ovulation should occur at a predictable time. The effectiveness of this syntheticprogestagen was evaluated in an ovulation induction protocol for Chinchilla lanigera applied togetherwith prostaglandin-F2α (PG-F2α). Two i.m. injections of PG-F2α (100 μg cloprostenol-sodium; Ciclase-DL) were applied 7 days apart to sixteen females. During those 7 days, 0.1 mg/kg/day of altrenogest(Progestal) was orally administrated to each animal. Half of the females also received 100 U.I. of eCG(Novormon-5000) at time of the second PG-F2α dose. All urine samples produced by the animals werecollected one week before, during and one week after the injections. Samples were analyzed for creatinine(CRT, Sigma #C3613), pregnanediol glucuronide and estrone conjugates (PdG-R13904, EC-R522-2,C.Munro) by EIA. The results obtained in both protocols showed that altrenogest applied with PG-F2αsuccessfully suppressed ovarian activity evidenced by the basal EC and PdG concentrations observedduring the days of administration, with the exception of a slight increment in PdG levels in one of theprotocols, attributed to oral administration of the synthetic progestagen, which is excreted mainly as PdG.After altrenogest withdrawal, an increase in EC and PdG levels as sign of ovarian activation, was observedonly in the protocol that also included an eCG injection. It is likely that the altrenogest dose administeredwas too high and probably produced an excessive reduction in ovarian activity and therefore, theprogesterone withdrawal alone was not enough to induce ovulation. The study reported here was approvedby the IACUC of the Faculty of Medicine.