Effects of protein kinase A and C inhibitors on follicular inhibin and activin during ovulation

Pharmacological investigation of vitamin E with combined oral contraceptives on INHBA gene against PCOS that intricate through melatonin PKC pathway

The most prevalent endocrine and metabolic condition in women of reproductive age are polycystic ovary syndrome (PCOS) with significant risk factors such as circadian rhythm and melatonin disruption. The aim of this study is to assess the effect of vitamin E in combination with a combined oral contraceptive (COC) on continuous light-induced PCOS using hormonal measures, oxidative stress (OS) indicators, and the inhibin beta-A (INHBA) gene, which targets the melatonin protein kinase C (PKC) pathway. An in silico technique anticipated INHBA's binding affinity for vitamin E and COC. For the in vivo investigation (IAEC/240/2021), female SD rats were divided into six groups and subjected to a 16-week induction period, followed by a 2-month test drug treatment with drospirenone (DRSP) as a standard. Serum testosterone, FSH, melatonin, and OS were calculated as hormonal markers. The expression of the INHBA gene was studied to see if it could be linked to the circadian rhythm and OS via the melatonin PKC pathway. According to the in silico study, vitamin E and DRSP had higher binding energy for the INHBA (-8.6 kcal/mol and -8.4 kcal/mol, respectively). When compared to the control group, in vivo results showed a substantial decrease in testosterone levels (p = .05), as well as changes in FSH (p = .78) and melatonin (p = .13). IHNBA gene expression has also dramatically increased, stimulating FSH production in the pituitary gland. Vitamin E and COC concomitantly are beneficial against PCOS because it modulates OS, which in turn influences circadian rhythm and the melatonin PKC pathway.

PKC-βII is downregulated in the premature ovarian failure SD rat model

We investigated the role of protein kinase c (PKC) -α and -β during the ovarian follicular dynamics using estrous cycle, gonadotropin-induced ovulation, and antral follicle culture, 4-vinylcyclohexene diepoxide (VCD)-induced premature ovarian failure (POF) in the SD rat models. We found the higher activity of PKC during the proestrus stage along with expression of PKC-α during the estrus and metestrus stages of the estrous cycle while PKC-β expression was increased during the diestrus, proestrus, and estrus stages. In response to pregnant mare gonadotropin (PMSG)-induced follicular recruitment and ovulation, the phosphorylated (Thr-642) PKC-β was increased. PKC activity inhibition by hispidin during the proestrus stage resulted in decreased antral follicles and corpus luteum. Treatment with hispidin resulted in the downregulation of granulosa cell (GC) biomarker, follicle stimulating hormone receptor (FSHR) expression in the cultured pre-antral follicle. During the forskolin-induced luteinization of human granulosa cells, the expression level of PKC-α and β (I and II) was decreased. In the POF condition, the activity of total PKC and the expression levels of PKC-α and β (I and II) were increased. Immunostaining depicted ubiquitous expression of PKC-α in the ovary during the estrous cycle and POF conditions. Taken together, we conclude the association of PKC-α and -β (I and II) during ovarian follicular dynamics where the expression level of PKC-α is increased, but the expression level of PKC-β (I and II) is suppressed in the POF condition in the SD rat model.

An Update on In Vitro Folliculogenesis: A New Technique for Post-Cancer Fertility

Introduction: Obtaining in vitro mature oocytes from ovarian tissue to preserve women’s fertility is still a challenge. At present, there is a therapeutic deadlock for girls and women who need emergency fertility preservation in case of a high risk of ovary invasion by malignant cells. In such a case, ovarian tissue cannot be engrafted; an alternative could be in vitro folliculogenesis. Methods: This review focuses on the progress of in vitro folliculogenesis in humans. PubMed and Embase databases were used to search for original English-language articles. Results: The first phase of in vitro folliculogenesis is carried out in the original ovarian tissue. The addition of one (or more) initiation activator(s) is not essential but allows better yields and the use of a 3D culture system at this stage provides no added value. The second stage requires a mechanical and/or enzymatic isolation of the secondary follicles. The use of an activator and/or a 3D culture system is then necessary. Conclusion: The current results are promising but there is still a long way to go. Obtaining live births in large animals is an essential step in validating this in vitro folliculogenesis technique.

Activin A in Mammalian Physiology

Activins are dimeric glycoproteins belonging to the transforming growth factor beta superfamily and resulting from the assembly of two beta subunits, which may also be combined with alpha subunits to form inhibins. Activins were discovered in 1986 following the isolation of inhibins from porcine follicular fluid, and were characterized as ovarian hormones that stimulate follicle stimulating hormone (FSH) release by the pituitary gland. In particular, activin A was shown to be the isoform of greater physiological importance in humans. The current understanding of activin A surpasses the reproductive system and allows its classification as a hormone, a growth factor, and a cytokine. In more than 30 yr of intense research, activin A was localized in female and male reproductive organs but also in other organs and systems as diverse as the brain, liver, lung, bone, and gut. Moreover, its roles include embryonic differentiation, trophoblast invasion of the uterine wall in early pregnancy, and fetal/neonate brain protection in hypoxic conditions. It is now recognized that activin A overexpression may be either cytostatic or mitogenic, depending on the cell type, with important implications for tumor biology. Activin A also regulates bone formation and regeneration, enhances joint inflammation in rheumatoid arthritis, and triggers pathogenic mechanisms in the respiratory system. In this 30-yr review, we analyze the evidence for physiological roles of activin A and the potential use of activin agonists and antagonists as therapeutic agents.

Growth Hormone Releasing Peptide-2 Attenuation of Protein Kinase C-Induced Inflammation in Human Ovarian Granulosa Cells

Cyclooxygenase-2 (COX-2) and interleukin-8 (IL-8) are two important inflammatory mediators in ovulation. Ghrelin may modulate inflammatory signaling via growth hormone secretagogue receptors. We investigated the role of ghrelin in KGN human ovarian granulosa cells using protein kinase C (PKC) activator phorbol 12, 13-didecanoate (PDD) and synthetic ghrelin analog growth hormone releasing peptide-2 (GHRP-2). GHRP-2 attenuated PDD-induced expression of protein and mRNA, the promoter activity of COX-2 and IL-8 genes, and the secretion of prostaglandin E2 (PGE₂) and IL-8. GHRP-2 promoted the degradation of PDD-induced COX-2 and IL-8 proteins with the involvement of proteasomal and lysosomal pathways. PDD-mediated COX-2 production acts via the p38, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways; PDD-mediated IL-8 production acts via the p38, JNK and ERK pathways. GHRP-2 reduced the PDD-induced phosphorylation of p38 and JNK and activator protein 1 (AP-1) reporter activation and PDD-induced NF-κB nuclear translocation and reporter activation. The inhibitors of mitogen-activated protein kinase phosphatase-1 (MKP-1) and protein phosphatase 2 (PP2A) reduced the inhibitory effect of GHRP-2 on PDD-induced COX-2 and IL-8 expression. Our findings demonstrate an anti-inflammatory role for ghrelin (GHRP-2) in PKC-mediated inflammation of granulosa cells, at least in part, due to its inhibitory effect on PKC-induced activation of p38, JNK and NF-κB, possibly by targeting to MKP-1 and PP2A.

Identification of new ovulation-related genes in humans by comparing the transcriptome of granulosa cells before and after ovulation triggering in the same controlled ovarian stimulation cycle

STUDY QUESTION

Which genes and molecular mechanisms are involved in the human ovulatory cascade and final oocyte maturation?

SUMMARY ANSWER

Up-regulated genes in granulosa cells (GC) represented inflammation, angiogenesis, extracellular matrix, growth factors and genes previously associated with ovarian cancer, while down-regulated genes mainly represented cell cycle and proliferation.

WHAT IS KNOWN ALREADY

Radical changes occur in the follicle during final follicle maturation after the ovulatory trigger: these range from ensuring an optimal milieu for the oocyte in meiotic arrest to the release of a mature oocyte and remodeling into a corpus luteum. A wide range of mediators of final follicle maturation has been identified in rodents, non-human primates and cows.

STUDY DESIGN, SIZE, DURATION

Prospective cohort study including 24 women undergoing ovarian stimulation with the long gonadotrophin-releasing hormone agonist protocol during 2010-2012 at Holbæk Fertility Clinic. Nine paired samples of GC and 24 paired samples of follicular fluid (FF) were obtained before and after recombinant human chorionic gonadotrophin (rhCG) administration.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Nine paired (nine arrays before rhCG and nine arrays after rhCG) samples of GC mRNA were amplified and hybridized to Affymetrix Human Gene 1.0 ST GeneChip arrays, compared and bioinformatically analyzed. Eleven selected genes were validated by quantitative reverse transcriptase PCR. FF hormones were analyzed by enzyme-linked immunosorbent assay.

MAIN RESULTS AND THE ROLE OF CHANCE

Eleven hundred and eighty-six genes were differentially expressed (>2-fold, P<0.0001, false discovery rate <0.0012) when comparing GC isolated before and 36 h after hCG, among those were genes known to be expressed at ovulation, i.e. ADAMTS1 and HAS2. Many new ovulation-related genes were revealed, such as CD24, ANKRD22, CLDN11 and FBXO32. FF estrogen, androstenedione and anti-Müllerian hormone decreased significantly while progesterone increased, accompanied by radical changes in the expression of steroidogenic genes (CYP17A, CYP19A, HSD11B1 and HSD11B2, StAR). Genes related to inflammation, angiogenesis, extracellular matrix formation, growth factors and cancer were up-regulated while cell cycle genes were massively down-regulated. Seventy-two genes previously described in connection with ovarian cancer were among the highly regulated genes. In silico analysis for top upstream regulators of the ovulatory trigger suggested--besides LH--TNF, IGF1, PGR, AR, EGR1 (early growth response 1), ERK1/2 (extracellular signal regulated kinase 1/2) and CDKN1A (cyclin-dependent kinase inhibitor 1A) as potential mediators of the LH/hCG response.

LIMITATIONS, REASONS FOR CAUTION

The present dataset was generated from women under hormonal stimulation. However, comparison with a macaque natural cycle whole follicle ovulation dataset revealed major overlap, supporting the idea that the ovulation-related genes found in this study are relevant in the human natural cycle.

WIDER IMPLICATIONS OF THE FINDINGS

These data will serve as a research resource for genes involved in human ovulation and final oocyte maturation. Ovulation-related genes might be good candidate biomarkers of follicle and oocyte health. Further, some of the ovulation-related genes may serve as future ovarian cancer biomarkers.

STUDY FUNDING/COMPETING INTEREST(S)

Grants from the Research Fund of Region Sjælland are gratefully acknowledged. None of the authors declared any conflict of interest.

TRIAL REGISTRATION NUMBER

Not applicable.

Expression of INHβA and INHβB proteins in porcine oocytes cultured in vitro is dependent on the follicle size

The current study aimed to investigate differential expression of inhibin βA (INHβA) and inhibin βB (INHβB) in porcine oocytes before or after in vitro maturation (IVM) isolated from follicles of various sizes. Porcine oocytes isolated from large, medium and small follicles (40 from each) were used to study the INHβA and INHβB protein expression pattern using western blot analysis before or after 44 h of oocyte IVM. An increased expression of INHβA was found in oocytes collected from large and medium follicles compared with small follicles before or after IVM (P < 0.001, P < 0.05, respectively). Similarly, higher INHβB levels were observed in oocytes recovered from large follicles compared with small (P < 0.01). As INHβA and INHβB are expressed in both porcine follicular somatic cells and oocytes, it can be assumed that these transforming growth factor beta (TGFβ) superfamily factors are involved in the regulation of molecular bi-directional pathways during follicle and oocyte development, and can be recognized as markers of follicle and oocyte maturation. Moreover, the current study clearly demonstrated that inhibin expression is substantially associated with porcine follicle growth and development.

The cAMP analogue, dbcAMP affects release of steroid hormones by cultured rabbit ovarian cells and their response to FSH, IGF-I and ghrelin

The aim of the present study was to examine possible involvement of cAMP-dependent intracellular mechanisms in control of ovarian cell steroidogenesis and its response to hormonal regulators. For this purpose, we examined the influence of administration of dbcAMP, a cAMP analogue (50 microg/animal) in vivo, on release of progesterone, testosterone and estradiol by isolated ovarian fragments, as well their response to hormonal regulators of ovarian steroidogenesis-FSH, IGF-I and ghrelin (all added at doses of 100 ng/ml). It was observed, that administration of dbcAMP resulted reduction in progesterone and testosterone, but not of estradiol release by isolated ovarian fragments. In ovarian tissue isolated from control animals, additions of hormones were able to reduce release of progesterone (FSH, IGF-I and ghrelin) and increase release of testosterone (ghrelin) but did not change estradiol output. Previous administration of dbcAMP modified action of exogenous hormones: it inverted inhibitory action of FSH, IGF-I and ghrelin on progesterone release to stimulatory action and induced stimulatory action of IGF-I on testosterone release and stimulatory effect of FSH on estradiol output. The present observations confirm involvement of peptide hormones FSH, IGF-I and ghrelin in the control of rabbit ovarian steroid hormones release and demonstrate the involvement of cAMP-dependent intracellular mechanisms in down-regulation of rabbit ovarian steroidogenesis and in modification, but not in mediating effect of FSH, IGF-I and ghrelin on ovarian steroid hormones release.