CONICET | Buscador de Institutos y Recursos Humanos

The domestic cat (Felis catus) serves as a good model for biomedical research in reproduction based on highly conserved reproductive mechanisms it shares with humans. In addition, a better understanding of feline reproduction it may contribute to the conservation of endangered felids. Thus, the aim of this study was to analyze the expression of the chemokine (C-C) motif ligand 2 (MCP1, also known as CCL2) and its receptor CCR2 in the cat ovary. First, MCP1 and CCR2 protein expression was assessed in the domestic cat ovary during the natural estrous cycle. Ovaries from adult cats (n=32) at estrus (E), diestrus (D) and anestrus (A) stages were fixed in 10% neutral-buffered formalin and embedded in paraffin for general histology and immunohistochemistry. Second, we used a feline antral culture system, developed by our laboratory, to study the mRNA expression of MCP1 and CCR2 within the follicle wall after an LH stimulus. We previously showed that these antral follicles were able to respond to the gonadotropin stimulus in vitro, supporting their use to study follicle biology in general. Consequently, ovaries were removed from adult cats (n= 51) during the breeding season at unknown stages of the estrous cycle. Antral follicles larger than 0.5 mm were mechanically dissected, measured and individually cultured (n=131) for 0, 6, 12, 24 or 36 h in the absence (Control) or presence of recombinant human LH (75 mIU/ml; LH group). At the end of the culture period, the follicle walls were dissected and used for RNA extraction. Following cDNA synthesis, MCP1 and CCR2 mRNA expression was assessed by quantitative real-time PCR (qPCR). Higher CCR2 immunostaining was observed in theca and luteal cells in comparison to granulosa cells. Stroma cells showed scattered staining in all stages. MCP1 immunostaining intensity was high at all stages and in most cell types, including stroma, theca, granulosa and luteal cells. LH treatment showed a significant increased (p