Non-invasive endocrine monitoring of ovarian and adrenal activity in chinchilla (Chinchilla lanigera) females during pregnancy, parturition and early post-partum period

MASTROMONACO GF; CANTARELLI VI; GALEANO MG; BOURGUIGNON NS; GILMAN C; PONZIO MF

GENERAL AND COMPARATIVE ENDOCRINOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2015 vol. 213 p. 81 - 89

0016-6480

The chinchilla is a rodent that bears one of the finest and most valuable pelts in the world. The wild counterpartis, however, almost extinct because of a drastic past and ongoing population decline. The presentwork was developed to increase our knowledge of the reproductive physiology of pregnancy and postpartumestrus in the chinchilla, characterizing the endocrine patterns of urinary progesterone, estradiol,LH and cortisol metabolites throughout gestation and post-partum estrus and estimating the ovulationtiming at post-partum estrus.Longitudinal urine samples were collected once per week throughout pregnancy and analyzed for creatinine,cortisol, LH, estrogen and progesterone metabolite concentrations. To indirectly determine theovulation timing at post-partum estrus, a second experiment was performed using pregnant females subjectedto a post-partum in vivo fertilization scheme. Urinary progestagen metabolites increased abovebaseline levels in early pregnancy between weeks-8 and -11 respectively to parturition, and slightlydeclined at parturition time. Urinary estrogens showed rising levels throughout mid- and late pregnancy(weeks-9 to -6 and a further increase at week-5 to parturition) and decreased in a stepwise manner afterparturition, returning to baseline levels two weeks thereafter. Cortisol metabolite levels were relativelyconstant throughout pregnancy with a tendency for higher levels in the last third of gestation and afterthe pups? birth. Parturition was associated with dramatic reductions in urinary concentrations of sex steroids(especially progestagens). Observations in breeding farms indicated that the females that resulted ina second pregnancy after mating, did so on the second day after parturition. These data were in agreementwith an LH peak detected 24 h after parturition. Urinary steroid hormone patterns of estrogenand progestagen metabolites provided valuable information on endocrine events during pregnancy andafter parturition in the chinchilla. Results presented in this study enhance our understanding of naturalreproductive dynamics in the chinchilla and support empirical observations of breeders that post-partumovulation occurs 48 h after parturition