Tumor Necrosis Factor alpha and Ovulation in the Zebrafish (Danio rerio)
This study investigated the expression, regulation and actions of pro-inflammatory cytokines within the zebrafish ovary during the periovulatory period. Genes indicative of macrophages and representing the four major cytokines classes (Chemokines, Interferons, Interleukins and Tumor Necrosis Factors) were expressed in the zebrafish ovary. Only TNFαA, TNFαB, and the macrophage indicator CSF1-1 changed expression during the periovulatory period. Injections of Ovaprim to induce ovulation increased TNFαA expression. Full grown ovarian follicle incubations showed an increase in TNFαA and B mRNA and protein after treatment with protein kinase C (PKC) activators. Moreover, lipopolysaccharide treatment increased TNFαA and B mRNA, while prostaglandin E2 (PGE2) treatment reduced TNFαA. Other studies showed that murine TNFα stimulated the production of PGE2 and prostaglandin F2α (PGF2α) and a TNFα receptor blocker attenuated PKC induced PGE2 production, but stimulated PGF2α production. Collectively, these results suggest that cytokines, particularly TNFαA, play a role in prostaglandin production and the regulation of ovulation.