Felis catus as a model to study follicle biology in vitro

ROJO, JL; MUSSE, MP; PELUFFO, MC

Grand Rapids, Muchigan

Congreso; 47th SSR Annual Meeting; 2014

Society for the Study of Reproduction

Felis catus as a model to study follicle biology in vitro Julieta L. Rojo, Mariana P. Musse, Marina C. Peluffo Centro de Investigaciones Endocrinológicas "Dr. César Bergadá" (CEDIE),CONICET  FEI   División de Endocrinología, Hospital de Niños Ricardo Gutiérrez, Gallo 1330. CABA. C1425EFD The domestic cat (Felis catus) is classically defined as an induced ovulator with seasonal polyestrous. The cat is commonly used for the study of oocyte cryopreservation based on its potential to serve as a model species for biomedical research and the conservation of endangered felids. The cat also provides a unique and valuable physiological model to study molecular processes within the preovulatory follicle due to the fact that each animal provides between 3 to 7 preovulatory follicles, naturally selected in an "ovulation-ready" state "waiting" for the LH surge during estrous. Highly conserved reproductive mechanisms between humans and feline species have been recently reported, providing an excellent surrogate for understanding events within the ovary. Thus, the aim of this study was to evaluate the response of isolated feline antral follicles to LH. To test this, ovaries were removed from adult female domestic cats (n=15) during the breeding season at unknown stages of the estrous cycle. Antral follicles larger than 0.5 mm were mechanically dissected from the ovary, measured and individually cultured (n=112) for 12 or 24 hr in the absence (Control group) or presence of recombinant human LH (75 mIU/ml; LH group). Out of the total isolated antral follicles one was a preovulatory follicle (3.5 mm). Thus, results from this follicle were analyzed separately. At the end of the culture period, levels of estradiol (E2) and progesterone (P4) in the media were measured from representative samples from each group and time point (n=72) to evaluate their response to LH. Higher levels of P4 in the LH group (p<0.001) were observed after 12 or 24 hr of culture in comparison to their controls (0.82 ng/ml ± 0.094 vs. 0.016 ng/ml ± 0.004 and 1.08 ng/ml ± 0.11 vs. 0.064 ng/ml ± 0.022; respectively). Similar results were obtained for E2, with higher levels (p<0.05) in the LH group at 12 or 24 hr (1799.01 pg/ml ± 491.67 vs. 303.69 pg/ml ± 108.33 and 3499.01 pg/ml ± 1090.22 vs. 1055.90 pg/ml ± 288.34; respectively). The obtained results showed a wide range of hormone values within each group. At 12 hr of culture, levels of P4 varied from 0.001 up to 0.062 ng/ml (Control group) and from 0.208 up to 1.354 ng/ml (LH group).  Also 24 hr after culture, P4 levels varied from 0.001 up to 0.224 ng/ml in the Control group and from 0.404 up to 2.092 ng/ml in the LH group. In addition, E2 levels also varied at both time point (between 0.7 to 1592.4 pg/ml and 6.86 to 3589.0 pg/ml in the Control group; between 96.2 to 7477.0 pg/ml and 120.7 pg/ml to 14658.0 pg/ml in the LH group; at 12 or 24 hr, respectively). But, surprisingly, when hormone levels were analyzed according the follicle diameter (divided into 2 categories: < 1mm and ≥ 1 mm) within each treatment, this parameter did not correlate with E2 and P4 producing potential (p> 0.05). However, LH induced high levels of steroids in the isolated single preovulatory after 24 hr of culture (20476.5 pg/ml and 7.29 ng/ml; E2 and P4, respectively). These data indicate, for the first time in felines, that antral follicles of different diameters are able to respond to LH in vitro, supporting their use to study follicular development, steroidogenesis, periovulatory events as well as follicle biology in general. This study was supported by PRESTAMO BID PICT 2012 Nº 025 and by the Fogarty International Center, of the National Institutes of Health under Award Number R01TW009163.