Stromal-derived factor 1 directly promotes genes expressed within the ovulatory cascade in feline cumulus oocyte complexes.

PURPOSE: We hypothesized that the chemokine SDF1/CXCR4 system was present in feline cumulus-oocyte complexes (COCs) and that COCs cultured with SDF1 would directly upregulate gene expression in the ovulatory cascade. METHODS: Ovaries (n = 50) were obtained from adult domestic cats during the breeding season and COCs were recovered from antral follicles. Because IVM media triggers cumulus-oocyte expansion, culture conditions needed to be optimized to study periovulatory genes. After optimization, the effects of 25 ng/ml SDF1 and the CXCR4 inhibitor were examined in a COC culture for 3, 12, and 24 h. RESULTS: MEM-hepes with 1% of charcoal stripped-FBS was the optimized culture medium, assessed by the expansion of COCs at 24 h in the gonadotropin (GNT) group but not in the media with serum alone. The mRNA expression of HAS2, TNFAIP6, PTX3, and AREG peaked at 3 h in GNT group as compared to all other groups (p < 0.05). COCs cultured with SDF1 showed increased HAS2 and TNFAIP6 mRNA expression at 3 h compared to negative controls and to the CXCR4 inhibitor group. CXCR4 and SDF1 immunostaining was present in both cumulus cells and the oocyte. CONCLUSIONS: These results demonstrate that GNT stimulation upregulates key periovulatory genes and expansion in feline COCs from antral follicles, and support the use of this culture system to examine molecular processes within the COC. In addition, SDF1 directly promotes key periovulatory genes in feline COCs, suggesting that the SDF1-CXCR4 pathway may extend its function beyond a chemoattractant, and may play a direct role within the COC.

Felis catus ovary as a model to study follicle biology in vitro.

PURPOSE: The current study was designed to evaluate the response of individual intact antral follicles from adult female domestic cats to a luteinizing hormone (LH) stimulus in vitro by assessing cumulus-oocyte expansion (C-OE) and steroid production. METHODS: C-OE and steroid levels (estradiol [E2] and progesterone [P4]) obtained from individual antral feline follicles (n = 366 follicles; n = 56 cats) were analyzed after 12 or 24 h of culture in the presence or absence of LH (low [3.4 ng/ml] or high [100 ng/ml]). RESULTS: At the end of the culture, the highest percentage of expanded cumulus-oocyte complexes (COCs) was observed in the LH groups at 12 or 24 h in comparison to their controls (p < 0.001). There was a significant increase in expanded COCs when comparing LH concentrations (high vs. low) at 12 or 24 h. Higher levels of both E2 and P4 were observed in the media from antral follicles after 12 and 24 h of culture in the presence of LH (both concentration, p < 0.05). There was no association between hormone levels and follicle diameter; high variability was observed in the steroid levels produced by antral follicles within all treatment groups. CONCLUSIONS: These data indicate, for the first time, that feline antral follicles (0.5-2 mm) from different stages of the natural estrous cycle can be cultured and will respond to an LH stimulus, based on an increase in steroid levels as well as C-OE after 12 or 24 h in culture.