eCG stimulation in domestic cats increases the expression of gonadotrophin-induced genes improving oocyte competence during the non-breeding season.

The objective of this study was to evaluate the eCG stimulation on domestic cat oocyte competence during the non-breeding season. Four experimental groups were made: (a) untreated cycling cats (Breeding season group; BS), (b) untreated anestrous cats (Non-breeding group; NB), (c) anestrous cats treated with 200 IU of eCG (eCG group) and (d) anestrous cats treated with 200 IU of eCG and 100 IU of hCG four days later (hCG group). In the BS, NB and eCG groups, grade I and II immature cumulus-oocyte complexes (COCs) were subjected to in vitro maturation or used for the gene expression analysis of FSHR, LHCGR, EGFR, EGR1, ESR2, PTGS2, GDF9, BMP15 and GATM. The in vitro matured oocytes from the BS, NB and eCG groups and the in vivo matured oocytes from the hCG group were subjected to parthenogenetic activation. The grade I and II COCs from the eCG group had an increased expression of FSHR, LHCGR, EGFR, EGR1 and ESR2 and a higher maturation rate than the BS and NB groups (p < 0.05). After parthenogenetic activation, the blastocyst rate from the hCG, eCG and BS groups was higher than the NB group (p < 0.05). However, no significant improvement was observed in the blastocyst rate in the hCG group compared to the eCG group (p > 0.05). In conclusion, the eCG treatment increases the expression of specific genes improving the oocyte competence during the cat non-breeding season, which is reflected in an enhanced in vitro maturation and in vitro embryo development after parthenogenetic activation.

FSH stimulation of anestrous cats improves oocyte quality and development of parthenogenetic embryos.

In the domestic cat, the efficiency of in vitro embryo production systems is negatively affected during the nonbreeding season. The objective of this research was to evaluate the effect of FSH stimulation in anestrous cats, on quality of cumulus-oocyte complexes (COCs) and in vitro developmental competence after parthenogenetic activation. To accomplish this purpose, anestrous cats were grouped into: (1) FSH treated (serial doses of 5 mg of porcine FSH each, every 24 hours, for 4 days) and (2) untreated control. The COCs were classified morphologically and a proportion of grade I and II COCs was used for expression analysis of FSHR, LHCGR, EGFR, PTGS2, EGR1, GDF9, and GATM by RT-qPCR. In addition, another proportion of grade I and II COCs was matured in vitro and used for parthenogenetic activation. After 8 days in culture, blastocyst and hatching blastocyst rates were assessed, and the expression of OCT4, SOX2, NANOG, CDX2, and GATA6 was evaluated. The COCs in the FSH group had an enhanced quality, a higher expression of LHCGR and a lower expression of GATM than did COCs from the control group (P < 0.05). Furthermore, embryos in the FSH group had increased blastocyst and hatching blastocyst rates, and those embryos had a higher expression of OCT4 and GATA than their counterparts from the control group (P < 0.05). In conclusion, ovarian stimulation of anestrous cats with FSH improved quality and increased the expression of LHCGR in COCs. The enhanced in vitro developmental competence, after parthenogenetic activation of oocytes from FSH-treated cats, coincided with an increased expression of OCT4 and GATA6 in blastocysts and hatching blastocysts.