Noninvasive monitoring of ovarian endocrine activity in the chinchilla (Chinchilla lanigera).

BUSSO JM; PONZIO MF; CHIARAVIGLIO M; FIOL DE CUNEO M,; RUIZ RD

GENERAL AND COMPARATIVE ENDOCRINOLOGY

Elsevier Science.

Lugar: Gainesville, Florida; Año: 2007 vol. 150 p. 288 - 297

0016-6480

Reproductive endocrinology information is limited for Chinchilla lanigera; a south American species characterized by extremely long gestation and estrus cycle compared to others rodents. This study was designed to validate a non invasive technique for monitoring ovarian endocrine activity. Animals were exposed indoors to natural photoperiod (31° S - 64° W, Argentina); temperature range: 17-26 °C, with food and water ad libitum. Radiolabeled infusion (n=4): 3H-estradiol (2H-E2) and 14C-progesterone (14C-P4) were injected (i.p). Biochemical validation: HPLC-UV detector was employed to determine natural steroids in urine and fecal extracts and to determine immunoreactive metabolites. Physiological validation: 1) Pregnancy (n=5): body weight and urinary and fecal steroidal metabolites were measured until birth; 2) Seasonality (n=9): urine and feces were collected in May, August, November, and February. Total 2H-E2 and 14C-P4 radioactivity recovered was 60.5 ± 15.5 and 74.5 ± 19.4 %, respectively. After 2H-E2 injection, urinary radioactivity peaked at 7.0 ± 0.6 hr; in contrast, urinary 14C-P4 excretion peaked at 44.0 ± 4.0 hr (p=0.000). Peak radioactivity in feces occurred between 24-48 hr. Several correlations were detected for body weight vs. urinary progestagens/day (r= 0.44, p< 0.03); vs. urinary progestagens/creatinine (r= 0.73, p = 2.9x10-5); vs. urinary estrogens/day (r= 0.74; p<0.02); and vs. urinary estrogens/creatinine (r= 0.74; p<2.0x10-5). On the other hand, urinary and fecal progestagen excretion exhibited significant seasonal fluctuations and urinary estrogen concentrations showed a similar pattern (p= 0.062 for winter-spring vs. summer-autumn); hormone variation in urine was correlated (r=0.55; p=0.0024). This methodology proved to be useful for monitoring ovary endocrine activity in chinchilla.