P4 Production In Cells Research Articles

Steroidogenesis, proliferation and apoptosis in bovine granulosa cells: role of tumour necrosis factor-alpha and its possible signalling mechanisms.

This study was designed to investigate the presence of bioactive tumour necrosis factor-alpha (TNF-alpha) in bovine fluid collected from small (<5 mm) and large (>8 mm) follicles, as well as the production of the cytokine by the granulosa cells collected from the same type of follicles. Moreover, the effectiveness of 10, 1 and 0.1 ng mL(-1) of human TNF-alpha (hTNF-alpha) in affecting the main parameters of granulosa cell function, progesterone (P4) and oestradiol-17beta (E2) production, cell proliferation and apoptosis, was tested. In addition, the study aimed to determine whether the signalling mechanisms of TNF-alpha in these cells involve cAMP, nitric oxide or prostaglandin E2 (PGE2) and F2alpha (PGF2alpha). It emerged that bioactive TNF-alpha is present in follicular fluid from both types of follicles and can be measured in media conditioned by granulosa cells from large follicles. As for the effects of hTNF-alpha, it inhibits P4 production in cells from both types of follicles and stimulates E2 output in those from small follicles; it does not affect proliferation, but it stimulates granulosa cell apoptosis. Finally, the effects of hTNF-alpha on bovine granulosa cells are not mediated by nitric oxide or cAMP, as neither of these substances were affected by treatment with the cytokine; however, in some way, they could be mediated through PGE2 and PGF2alpha, the production of which was inhibited by TNF-alpha in cells from small follicles.

The lipoxygenase pathways are involved in LH-stimulated progesterone production in bovine corpus luteum

We have examined the effects of endogenous lipoxygenase products on basal progesterone (P4) production by cultured bovine mid-luteal cells. The involvement of lipoxygenase products in the stimulatory effect of LH on luteal cAMP accumulation and P4 production was also examined. Bovine luteal cells from mid-cycle corpora lutea (CL) were exposed for 16 h to a lipoxygenase inhibitor (nordihydroguaiaretic acid: NDGA; 0.33–33 μM). For the last 4 h of incubation, the cells were exposed to LH and/or three different lipoxygenase products, 5-, 12- and 15-hydroxyeicosatetraenoic acid (HETE). NDGA inhibited P4 production by the cells in a dose-dependent manner ( P < 0.05). NDGA-reduced P4 production was reversed by the addition of 12-HETE, but not 5- or 15-HETE, whereas 5-, 12- and 15-HETE alone showed no significant effect on P4 production in the intact cells. Furthermore, NDGA (33 μM) blocked the stimulatory action of LH on P4 production ( P < 0.05), without changing cAMP accumulation ( P > 0.1). When the cells were exposed to 5-, 12- or 15-HETE with LH and NDGA, only 15-HETE maintained the stimulatory effect of LH on P4 production in the cells ( P < 0.05). These results suggest that endogenous lipoxygenase products play important roles in P4 production by bovine CL, i.e. basal P4 production is supported by 12-HETE, and LH-stimulated P4 production is partially mediated via the activation of lipoxygenase and subsequent 15-HETE formation downstream of the LH-activated cAMP-PKA-phosphorylation pathway.