Porcine follicular fluids: Comparison of solid-phase extraction and matrix solid-phase dispersion for the GC–MS determination of hormones during follicular growth

The role of estrogen metabolites in human ovarian function

Estrogens produced by the ovary play diverse roles in controlling physiological changes in the function of the female reproductive system. Although estradiol acts through classical nuclear receptors, its metabolites (EMs) act by alternative pathways. It has been postulated that EMs act through paracrine-autocrine pathways to regulate key processes involved in normal follicular growth, corpus luteum (CL) development, function, and regression. The present review describes recent advances in understanding the role of EMs in human ovarian physiology during the menstrual cycle, including their role in anovulatory disorders and their action in other target tissues.

17β-estradiol improves the developmental ability, inhibits reactive oxygen species levels and apoptosis of porcine oocytes by regulating autophagy events

OBJECTIVES

Estrogen plays a critical role in the development and apoptosis of oocytes. Autophagy is an evolutionarily conserved and exquisitely regulated self-eating cellular process with important biological functions including the regulation of reproduction. This study aimed to determine the effect of autophagy regulated by the biologically active form of estrogen (17β-estradiol) in porcine oocyte maturation in vitro.

MATERIALS AND METHODS

We measured the effects of oocyte developmental competencies and autophagic activity in the porcine oocyte regulated by 17β-estradiol using autophagic inhibitor (Autophinib). In addition, we studied the role of autophagy in reactive oxygen species (ROS) levels, mitochondrial distribution, Ca²⁺ production, mitochondrial membrane potential (ΔΨm), and early apoptosis by caspase-3, -8 activity in the mature oocytes.

RESULTS

The results showed that the oocyte meiotic progression and early embryonic development were gradually decreased with Autophinib treatment, which was improved by 17β-estradiol. Immunofluorescence experiments revealed that 17β-estradiol primarily could promote the autophagy in the mature oocytes, and block the reduced-autophagic events by Autophinib. Moreover, 17β-estradiol improved the Autophinib induced high ROS levels, abnormal mitochondrial distribution and low Ca²⁺ production in mature oocytes. Analyses of early apoptosis and ΔΨm showed that autophagy inhibition was accompanied by increased cellular apoptosis, and 17β-estradiol reduced apoptosis rates of mature oocytes. Importantly, autophagy was downregulated by treatment with Autophinib, an activation of caspase-8 and cleaved caspase-3 increased. Those effects were abolished by 17β-estradiol, which could upregulate autophagy.

CONCLUSIONS

Our study have showed important implications that 17β-estradiol could promote efficacy of the development of porcine oocytes, enhance the autophagy, reduce ROS levels and apoptosis activity in vitro maturation.

Phospholipase C inhibits apoptosis of porcine primary granulosa cells cultured in vitro

Phospholipase C (PLC) can participate in cell proliferation, differentiation and aging. However, whether it has a function in apoptosis in porcine primary granulosa cells is largely uncertain. The objective of this study was to examine the effects of PLC on apoptosis of porcine primary granulosa cells cultured in vitro. The mRNA expression of BAK, BAX and CASP3, were upregulated in the cells treated with U73122 (the PLC inhibitor). The abundance of BCL2 mRNA, was upregulated, while BAX and CASP3 mRNA expression was decreased after treatment with m-3M3FBS (the PLC activator). Both the early and late apoptosis rate were maximized with 0.5 μM U73122 for 4 h. The rate of early apoptosis was the highest at 4 h and the rate of late apoptosis was the highest at 12 h in the m-3M3FBS group. The protein abundance of PLCβ1, protein kinase C β (PKCβ), calmodulin-dependent protein kinaseII α (CAMKIIα) and calcineurinA (CalnA) were decreased by U73122, and CAMKIIα protein abundance was increased by m-3M3FBS. The mRNA expression of several downstream genes (CDC42, NFATc1, and NFκB) was upregulated by PLC. Our results demonstrated that apoptosis can be inhibited by altering PLC signaling in porcine primary granulosa cells cultured in vitro, and several calcium^-sensitive targets and several downstream genes might take part in the processes.

The effects of phospholipase C on oestradiol and progesterone secretion in porcine granulosa cells cultured in vitro

Granulosa cells play important roles in the regulation of ovarian functions. Phospholipase C is crucial in several signalling pathways and could participate in the molecular mechanisms of cell proliferation, differentiation and ageing. The objective of this study was to identify the effects of phospholipase C on the steroidogenesis of oestradiol and progesterone in porcine granulosa cells cultured in vitro. Inhibitor U73122 or activator m-3M3FBS of phospholipase C was added to the in vitro medium of porcine granulosa cells, respectively. The secretion of oestradiol decreased after 2 hr, 8 hr, 12 hr, 24 hr and 48 hr of treatment with 500 nM U73122 (p < .05) and decreased after 2 hr of treatment in the 500 nM m-3M3FBS addition group (p < .05). The secretion of progesterone increased after 4 hr of treatment with 500 nM U73122 (p < .05) and increased after 2 hr and 8 hr of treatment in the 500 nM m-3M3FBS addition group (p < .05). The ratio of oestradiol to progesterone decreased at each time point, except 8 hr after the addition of 500 nM U73122 (p < .05). The ratio of oestradiol to progesterone decreased after 2 hr (p < .05) of treatment with 500 nM m-3M3FBS. In genes that regulate the synthesis of oestradiol or progesterone, the mRNA expression of CYP11A1 was markedly increased (p < .05), and the mRNA expression of other genes did not change significantly in the U73122 treatment group, while the addition of m-3M3FBS did not change those genes significantly despite the contrary trend. Our results demonstrated that phospholipase C can be a potential target to stimulate the secretion of oestradiol and suppress progesterone secretion in porcine granulosa cells cultured in vitro, which shed light on a novel biological function of phospholipase C in porcine granulosa cells.

2-hydroxyoestradiol and 2-methoxyoestradiol, two endogenous oestradiol metabolites, induce DNA fragmentation in Sertoli cells

Elevated intratesticular levels of hydroxyoestradiols and methoxyoestradiols, two classes of endogenous oestradiol metabolites, have been associated with male infertility. The aim of this study was to explore the effects of 2-hydroxyoestradiol (2OHE₂ ), 4-hydroxyoestradiol (4OHE₂ ), 2-methoxyoestradiol (2ME₂ ) and 4-methoxyoestradiol (4ME₂ ) on Sertoli cell viability. For this, TM4 cells were incubated with different concentrations of these metabolites for 24 h to then evaluate the viability and DNA integrity by MTS and TUNEL assay respectively. The participation of classical oestrogen receptors and the involvement of oxidative stress and apoptotic mechanisms were also evaluated co-incubating TM4 cells with these estradiol metabolites and with the drugs ICI182780, N-acetylcysteine and Z-VAD-FMK respectively. Only high concentrations of 2OHE₂ and 2ME₂ decreased cell viability inducing DNA fragmentation. In addition, ICI182780 did not block the effect of 2OHE₂ and 2ME₂ , while N-Acetylcysteine and Z-VAD-FMK only blocked the effect of 2OHE₂ . Moreover, 2OHE₂ but not 2ME₂ induced PARP and caspase-3 cleavage. Finally, lower 2OHE₂ and 2ME₂ concentrations (0.01-0.1-1.0 μmol l^-1 ) decreased Sertoli cell viability 48 h post-treatment. Our results support the hypothesis that elevated intratesticular 2OHE₂ or 2ME₂ concentrations could be related to male infertility since 2OHE₂ by apoptosis and 2ME₂ by undetermined mechanisms induce DNA fragmentation in Sertoli cells.

Hypoxia stimulates the production of the angiogenesis inhibitor 2-methoxyestradiol by swine granulosa cells

We previously demonstrated the presence of 2-methoxyestradiol (2-ME) in swine follicular fluid. Present study was aimed first of all to investigate if swine granulosa cell produce 2-ME; in addition, we tried to assess a potential effect of hypoxia in modulating 2-ME output. Finally, we explored the effect of 2-ME in an angiogenesis bioassay set up in our lab. Our data show that cultured granulosa cells are able to produce 2-ME; interestingly, the secretion of the hormone appeared to be stimulated by hypoxia. Angiogenesis bioassay points out that 2-ME displays an inhibitory effect on neovascularisation. Therefore our data suggest that 2-ME could be a local effector in determining the fine tuning responsible for follicle angiogenesis. These data deserve special attention since the ovary is a valuable experimental model in angiogenesis research.