TRPV2, a novel player in the human ovary and human granulosa cells

The cation channel 'transient receptor potential vanilloid 2' (TRPV2) is activated by a broad spectrum of stimuli, including mechanical stretch, endogenous and exogenous chemical compounds, hormones, growth factors, reactive oxygen species, and cannabinoids. TRPV2 is known to be involved in inflammatory and immunological processes, which are also of relevance in the ovary. Yet, neither the presence nor possible roles of TRPV2 in the ovary have been investigated. Data mining indicated expression, for example, in granulosa cells (GCs) of the human ovary in situ, which was retained in cultured GCs derived from patients undergoing medical reproductive procedures. We performed immunohistochemistry of human and rhesus monkey ovarian sections and then cellular studies in cultured GCs, employing the preferential TRPV2 agonist cannabidiol (CBD). Immunohistochemistry showed TRPV2 staining in GCs of large antral follicles and corpus luteum but also in theca, endothelial, and stromal cells. TRPV2 transcript and protein levels increased upon administration of hCG or forskolin. Acutely, application of the agonist CBD elicited transient Ca2+ fluxes, which was followed by the production and secretion of several inflammatory factors, especially COX2, IL6, IL8, and PTX3, in a time- and dose-dependent manner. CBD interfered with progesterone synthesis and altered both the proteome and secretome, as revealed by a proteomic study. While studies are somewhat hampered by the lack of highly specific TRPV2 agonist or antagonists, the results pinpoint TRPV2 as a modulator of inflammation with possible roles in human ovarian (patho-)physiology. Finally, as TRPV2 is activated by cannabinoids, their possible ovarian actions should be further evaluated.

Human granulosa cells: insulin and insulin-like growth factor-1 receptors and aromatase expression modulation by metformin

BACKGROUND/AIM

Granulosa cells are the source of the most important ovarian steroids. Even in patients without significant improvement in metabolic parameters, metformin has apparently an important effect on the ovary. The aim of this study was to evaluate gene and protein expression of an insulin receptor (IR), insulin-like growth factor-1 (IGF1) receptor (IGF1R) and aromatase in granulosa cells treated with metformin and insulin.

METHODS

Luteinized granulosa cells were collected from 27 patients during in vitro fertilization procedures. Cells were isolated, stored in culture for 24 h and divided into four groups: control; metformin for 30 min, and metformin for 30 min plus insulin for 30 or 60 min.

RESULTS

IR and IGF1R mRNA expression was significantly enhanced by metformin but was not affected by insulin. Aromatase mRNA expression was significantly reduced in metformin-incubated cells following stimulation with insulin for 30 min. No statistical differences were found in IGF1R and aromatase protein expression, and IR expression was not detected.

CONCLUSION

A direct effect of metformin on the gene expression of IGF1R, IR and aromatase was observed. Further studies should investigate the role of IGF1R, IR and aromatase in ovarian physiology for a better understanding of the effect of metformin.