Effects of isoliquiritigenin on ovarian antral follicle growth and steroidogenesis

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

Progesterone Signaling and Uterine Fibroid Pathogenesis; Molecular Mechanisms and Potential Therapeutics

Uterine fibroids (UFs) are the most important benign neoplastic threat to women's health worldwide, with a prevalence of up to 80% in premenopausal women, and can cause heavy menstrual bleeding, pain, and infertility. Progesterone signaling plays a crucial role in the development and growth of UFs. Progesterone promotes the proliferation of UF cells by activating several signaling pathways genetically and epigenetically. In this review article, we reviewed the literature covering progesterone signaling in UF pathogenesis and further discussed the therapeutic potential of compounds that modulate progesterone signaling against UFs, including selective progesterone receptor modulator (SPRM) drugs and natural compounds. Further studies are needed to confirm the safety of SPRMs as well as their exact molecular mechanisms. The consumption of natural compounds as a potential anti-UFs treatment seems promising, since these compounds can be used on a long-term basis-especially for women pursuing concurrent pregnancy, unlike SPRMs. However, further clinical trials are needed to confirm their effectiveness.

Isoliquiritigenin induces neurodevelopmental-toxicity and anxiety-like behavior in zebrafish larvae

Isoliquiritigenin, a flavonoid compound, exhibits a variety of pharmacological properties, including anti-inflammatory, anti-oxidative, anti-microbial, anti-viral, and anti-tumor effects. In the past few years, the consumption of isoliquiritigenin-containing dietary supplements has increased due to their health benefits. Although the neuroprotective effects of isoliquiritigenin have been well-investigated, these studies were performed in cells and adult animals. The potential effects of isoliquiritigenin on the development, especially the neurodevelopment, of certain populations, such as zebrafish larvae, have not been investigated. In this study, zebrafish larvae were employed as a model to investigate the effects of isoliquiritigenin on development and neurodevelopment. Zebrafish embryos treated with high concentrations of isoliquiritigenin (10 and 15 μM) exhibited high rates of mortality, hatching, and malformation, indicating that isoliquiritigenin can affect zebrafish development. In addition, isoliquiritigenin impeded the development of central nervous system regions and the length of dopaminergic neurons located in midbrains and thalami of transgenic zebrafish larvae. The locomotor ability of zebrafish larvae exposed to high concentrations of isoliquiritigenin was negatively affected. The total distance and the average velocity significantly decreased, and anxiety-related behaviors were observed under light-dark challenge. Furthermore, the levels of gap43, tuba1b, mbp, hcrt, vmat2, and pomc, which mediate neurodevelopment, neurotoxicity, and anxiety were significantly decreased in zebrafish larvae exposed to isoliquiritigenin. These results indicate that isoliquiritigenin can disrupt the development of dopaminergic neurons and the function of the central nervous system in zebrafish, causing anxiety-like symptoms.

Isoliquiritigenin induces oxidative stress and immune response in zebrafish embryos

Isoliquiritigenin (ISL) is used in many households' personal hygiene and medicinal products, and the average human daily ISL exposure is 1-2 mg/kg. However, the molecular mechanisms of ISL toxicity in zebrafish embryos have not been fully elucidated. We investigated whether exposure to ISL induces oxidative stress and inflammatory responses in zebrafish. And exposure to ISL significantly affects the expression of immune response-related genes in zebrafish embryos following oxidative stress and the release of pro-inflammatory mediators through Toll-like receptor signaling.

Impact of fermented Broussonetia papyrifera on laying performance, egg quality, lipid metabolism, and follicular development of laying hens

Hybrid Broussonetia papyrifera (BP) has been widely planted and commonly used as ruminant forage source after fermentation in China. Very less information is available to know the impact of fermented BP on laying hens, thus, we have investigated effects of dietary supplementation of Lactobacillus plantarum-fermented B. papyrifera (LfBP) on laying performance, egg quality, serum biochemical parameters, lipid metabolism, and follicular development of laying hens. A total of 288 HY-Line Brown hens (age, 23 wk) were randomly assigned into 3 treatment groups: control group (Con, a basal diet), LfBP1 and LfBP5 group (a basal diet supplemented with 1% or 5% LfBP). Each group has 8 replicates of twelve birds each. The results demonstrated that dietary supplementation of LfBP increased average daily feed intake (linear, P < 0.05), feed conversion ratio (linear, P < 0.05), and average egg weight (linear, P < 0.05) during the entire experimental period. In addition, dietary inclusion of LfBP enhanced the egg yolk color (linear, P < 0.01) but decreased the eggshell weight (quadratic, P < 0.05) and eggshell thickness (linear, P < 0.01). In serum, the LfBP supplementation linearly decreased the content of total triglyceride (linear, P < 0.01) but increased the content of high density lipoprotein-cholesterol (linear, P < 0.05). The gene expression related to hepatic lipid metabolism including acetyl-CoA carboxylase, fatty acid synthase, and peroxisome proliferator-activated receptor (PPARα) was down-regulated whereas liver X receptor was up-regulated in LfBP1 group. Moreover, LfBP1 supplementation remarkably reduced the F1 follicle number and ovarian gene expression of reproductive hormone receptors including estrogen receptor, follicle stimulating hormone receptor, luteinizing hormone receptor, progesterone receptor, prolactin receptor, and B cell lymphoma-2. In conclusion, dietary inclusion of LfBP could improve feed intake, egg yolk color, and lipid metabolism, but may cause a decline in eggshell quality with higher inclusion level, herein, 1% is suggested.

A pH/Time/Pectinase-Dependent Oral Colon-Targeted System Containing Isoliquiritigenin: Pharmacokinetics and Colon Targeting Evaluation in Mice

BACKGROUND AND OBJECTIVES

Oral colon-targeted gel beads containing isoliquiritigenin (ISL) were successfully designed in our study. In order to further explore the targeting of the colon by the gel beads, a systematic study of their in vivo pharmacokinetics and colon targeting was performed in mice.

METHODS

Eighteen male mice were included in this study. The mice were separated into six groups at random. We collected blood, stomach, duodenum, jejunum, ileum, and colon tissues at 2, 4, 6, 8, 12, and 24 h after oral administration of gel beads containing isoliquiritigenin at a dose of 20 mg/kg. Gel beads in tissues were recorded and taken out to observe their swelling and erosion. The total ISL concentrations in different tissues and gel beads were analyzed by high-performance liquid chromatography.

RESULTS

All gel beads reached the upper part of the stomach at 2 h with no obvious swelling. Most of the gel beads were still in the lower part of stomach, while a small amount had reached the small intestine at 4 h. A few gel beads reached the colon and swelled at 6 h. Furthermore, the gel beads in the colon were swollen and erosive at 8 h. Meanwhile, the plasma ISL concentration could be detected, which indicated that the ISL in the gel beads was absorbed. At 12 h, the gel beads were almost dissolved and the plasma concentration was 8.33 times that at 8 h. At 24 h, the gel beads had completely disappeared, and the plasma concentration was 2.55 times that at 12 h.

CONCLUSION

The gel beads containing ISL are a sustained, controlled, and colon-targeting delivery system that can alter the ISL distribution in the gastrointestinal tract.

MiR-31 targets HSD17B14 and FSHR, and miR-20b targets HSD17B14 to affect apoptosis and steroid hormone metabolism of porcine ovarian granulosa cells

Porcine 17-hydroxysteroid dehydrogenase type 14 (HSD17B14) and FSH reporter (FSHR) genes play important roles in the metabolism of steroid hormones and the apoptosis of ovarian granulosa cells (GCs). Our bioinformatics analyses and the dual luciferase reporter assays indicated that porcine miR-20b and miR-31 target the 3'-UTR region of HSD17B14 gene, and miR-31 also targets the 3'-UTR region of FSHR gene. Overexpression of porcine HSD17B14 gene promoted the conversion from estradiol (E2) to estrone (E1) and increased the apoptosis of porcine GCs. Overexpression of miR-20b down-regulated the mRNA and protein expression level of HSD17B14 gene, decreased the concentration of progesterone (P4) and E1, increased E2, as well as reduced apoptosis of GCs. Moreover, overexpression of miR-31 also down-regulated the protein expression level of HSD17B14 gene, decreased the concentration of P4 and E1, and increased E2. However, miR-31 promoted apoptosis of GCs by targeting to the 3'-UTR of porcine FSHR gene. Taken together, we found that both porcine miR-20b and miR-31 target HSD17B14 gene, but miR-31 also targets FSHR gene to regulate the metabolism of steroid hormones and the apoptosis of porcine ovarian GCs. These findings expand the epigenetic regulatory mechanism of porcine miR-31 and miR-20b in ovarian GCs.

Isoliquiritigenin, a potent human monoamine oxidase inhibitor, modulates dopamine D1, D3, and vasopressin V1A receptors

Isoliquiritigenin (= 4,2′,4′-Trihydroxychalcone) (ILG) is a major constituent of the Glycyrrhizae Rhizoma that has significant neuroprotective functions. In the present study, we re-examined the potential of ILG to inhibit human monoamine oxidase (hMAO) in vitro and established its mechanism of inhibition through a kinetics study and molecular docking examination. ILG showed competitive inhibition of hMAO-A and mixed inhibition of hMAO-B with IC₅₀ values of 0.68 and 0.33 µM, respectively, which varied slightly from the reported IC₅₀ values. Since ILG has been reported to reduce dopaminergic neurodegeneration and psychostimulant-induced toxicity (both of which are related to dopamine and vasopressin receptors), we investigated the binding affinity and modulatory functions of ILG on dopamine and vasopressin receptors. ILG was explored as an antagonist of the D₁ receptor and an agonist of the D₃ and V_1A receptors with good potency. An in silico docking investigation revealed that ILG can interact with active site residues at target receptors with low binding energies. These activities of ILG on hMAO and brain receptors suggest the potential role of the compound to ameliorate dopaminergic deficits, depression, anxiety, and associated symptoms in Parkinson’s disease and other neuronal disorders.

Molecular mechanisms underlying the anticancer activities of licorice flavonoids

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice has been commonly used in traditional Chinese medicine for treatment of gastric, liver, and respiratory disease conditions for more than two thousand years. It is a major component of several Chinese patent medicines certificated by National Medical Products Administration that possess great anticancer activities.

AIM OF THE STUDY

To comprehensively summarize the anticancer activities of licorice flavonoids, explain the underlying molecular mechanisms, and assess their therapeutic potentials and side-effects.

METHODS

PubMed, Research Gate, Web of Science, Google Scholar, academic journals, and Science Direct were used as information sources, with the key words of "anticancer", "licorice", "flavonoids", and their combinations, mainly from 2000 to 2019.

RESULTS

Sixteen licorice flavonoids are found to possess anticancer activities. These flavonoids inhibit cancer cells through blocking cell cycle and regulating multiple signaling pathways. The major pathways targeted by licorice flavonoids include: the MAPK pathway, PI3K/AKT pathway, NF-κB pathway, death receptor - dependent extrinsic signaling pathway, and mitochondrial apoptotic pathway.

CONCLUSION

Licorice flavonoids are a group of versatile molecules that have pleiotropic effects on cell growth, survival and cell signaling. Many of the flavonoids possess inhibitory activities toward cancer cell growth and hence have a great therapeutic potential in cancer treatment. However, additional preclinical studies are still needed to assess their in vivo efficacy and possible toxicities. It is also imperative to evaluate the effects of licorice flavonoids on the metabolism of other drugs and explore the potential synergistic mechanism.

Perspectives on the Role of Isoliquiritigenin in Cancer

Isoliquiritigenin (2',4',4-trihydroxychalcone, ISL), one of the most important bioactive compounds with a chalcone structure, is derived from licorice root. Licorice is commonly known as Glycyrrhiza, including Glycyrrhiza uralensis, Glycyrrhiza radix, and Glycyrrhiza glabra, which are generally available in common foods and Chinese herbal medicines based on a wide variety of biological functions and pharmacological effects, and its derivative (ISL) is utilized as a food additive and adjunct disease treatment. In this review, we summarized the progress over the last 10 years in the targeted pathways and molecular mechanisms of ISL that are involved in the regulation of the onset and progression of different types of cancers.

The anti-diabetic activity of licorice, a widely used Chinese herb

ETHNOPHARMACOLOGICAL RELEVANCE

A great deal of valuable experience has been accumulated in the traditional Chinese medicine (TCM) system for the treatment of "Xiaoke" disease which is known as diabetes mellitus now. As the most-commonly used Chinese herb, licorice has been used in TCM for more than two thousand years. It is often used in combination with other herbs to treat metabolic disorders, especially diabetes mellitus.

AIM OF THE STUDY

To summarize the characteristics, mechanisms, and clinical use of licorice and its active components for treating diabetes mellitus.

METHODS

PubMed, Web of Science, Research Gate, Science Direct, Google Scholar, and Academic Journals were used as information sources by the inclusion of the search terms 'diabetes', 'licorice', 'licorice extracts', 'flavonoids', 'triterpenoids', and their combinations, mainly from 2005 to 2019.

RESULTS

Licorice extracts, five flavonoids and three triterpenoids isolated from licorice possess great antidiabetic activities in vivo and in vitro. This was done by several mechanisms such as increasing the appetency and sensitivity of insulin receptor site to insulin, enhancing the use of glucose in different tissues and organs, clearing away the free radicals and resist peroxidation, correcting the metabolic disorder of lipid and protein, and improving microcirculation in the body. Multiple signaling pathways, including the PI3K/Akt, AMPK, AGE-RAGE, MAPK, NF-кB, and NLRP3 signaling pathways, are targets of the licorice compounds.

CONCLUSION

Licorice and its metabolites have a great therapeutic potential for the treatment of diabetes mellitus. However, a better understanding of their pharmacological mechanisms is needed for evaluating its efficacy and safety.

In vitro ovarian follicle growth: a comprehensive analysis of key protocol variables†

Folliculogenesis is a complex process that requires integration of autocrine, paracrine, and endocrine factors together with tightly regulated interactions between granulosa cells and oocytes for the growth and survival of healthy follicles. Culture of ovarian follicles is a powerful approach for investigating folliculogenesis and oogenesis in a tightly controlled environment. This method has not only enabled unprecedented insight into the fundamental biology of follicle development but also has far-reaching translational applications, including in fertility preservation for women whose ovarian follicles may be damaged by disease or its treatment or in wildlife conservation. Two- and three-dimensional follicle culture systems have been developed and are rapidly evolving. It is clear from a review of the literature on isolated follicle culture methods published over the past two decades (1980-2018) that protocols vary with respect to species examined, follicle isolation methods, culture techniques, culture media and nutrient and hormone supplementation, and experimental endpoints. Here we review the heterogeneity among these major variables of follicle culture protocols.

Isoliquiritigenin triggers developmental toxicity and oxidative stress-mediated apoptosis in zebrafish embryos/larvae via Nrf2-HO1/JNK-ERK/mitochondrion pathway

Isoliquiritigenin (ISL) is an emerging natural flavonoid found in the roots of licorice, exhibits antioxidant, anti-cancer, anti-inflammatory, anti-allergic, cardioprotective, hepatoprotective and neuroprotective properties. However, the effect of ISL in embryonic development is yet to be elucidated, and the mechanisms underlying its target-organ toxicity and harmful side effects are still unclear. In the present study, we employed zebrafish embryos to study the developmental toxicity effect of ISL and its underlying mechanisms. Zebrafish embryos upon treatment with either vehicle control (0.1% DMSO) or ISL solutions for 4-96 h post fertilization (hpf) showed that ISL exposure instigated severe developmental toxicity in heart, liver, and nervous system. Mortality and morphological abnormalities were also observed. High concentrations of ISL exposure resulted in abnormal phenotypes and embryonic malformations including pericardial edema, swim bladder defects, yolk retention, curved body shape and shortening of body length. Moreover, ISL exposure led to significant loss of dopaminergic neurons accompanied by reduced locomotor behaviour. Apoptotic cells were predominantly located in the heart area of 96 hpf embryo. Additionally, ISL significantly increased the levels of reactive oxygen species, lipid peroxidation content and decreased antioxidant enzyme activities. The expressions pattern of apoptosis-related genes Bad, Cyto c, Caspase-9, Caspase-3 and Bax/Bcl-2 indicated that the oxidative stress-induced apoptosis triggered by ISL suggest involvement of Nrf2-HO1/JNK-ERK/mitochondrion pathways. In conclusion, here we provide first evidence that demonstrate ISL-induced dose-dependent developmental toxicity in zebrafish embryos. Furthermore, gene expression patterns in the embryos correlate the above and reveal potential genetic mechanisms of developmental toxicity.

MiR-31 and miR-143 affect steroid hormone synthesis and inhibit cell apoptosis in bovine granulosa cells through FSHR

The regulatory role of microRNAs (miRNAs) has been explored in ovarian cells, and the effects of miRNAs on gonadal development, apoptosis, ovulation, and steroid production have been reported. In this study, we analyzed the effects of follicle stimulating hormone (FSH) on miR-31 and miR-143 expression levels in bovine granulosa cells (GCs). Our results demonstrated that the FSH receptor (FSHR) is a common target gene of miR-31 and miR-143 in bovine GCs. We further analyzed the roles of miR-31 and miR-143 in bovine GCs by transfecting miR-31 and miR-143 mimics and inhibitors. The Western blot and RT-PCR results showed that miR-31 and miR-143 reduced the mRNA and protein expression levels of FSHR. Moreover, miR-31 overexpression decreased the secretion of progesterone (P4), and miR-143 overexpression decreased both the synthesis of P4 and the secretion of estrogen (E2). In contrast, miR-31 inhibition increased the secretion of progesterone (P4), and miR-143 inhibition increased both the synthesis of P4 and the secretion of E2. Finally, we analyzed the possible effects of miR-31 and miR-143 on bovine GC apoptosis. The results showed that transfection with miR-31 and miR-143 mimics promoted GC apoptosis and that miR-143 and miR-31 inhibition reduced the rate of apoptosis in bovine GCs. Taken together, our results indicate that miR-31 and miR-143 decrease steroid hormone synthesis and inhibit bovine GC apoptosis by targeting FSHR.

Isoliquiritigenin Protects Against Pancreatic Injury and Intestinal Dysfunction After Severe Acute Pancreatitis via Nrf2 Signaling

Severe acute pancreatitis (SAP) is a digestive system disease that is associated with a range of complications including intestinal dysfunction. In this study, we determined that the chalcone compound, isoliquiritigenin (ISL), reduces pancreatic and intestinal injury in a mouse model of SAP. These effects were achieved by suppressing oxidative stress and the inflammatory responses to SAP. This was evidenced by a reduction in histological score, and malondialdehyde (MDA), interleukin (IL)-6, tumor necrosis factor (TNF)-α and cleaved-caspase-3 (c-caspase-3) protein along with an increase in Nrf2, hemeoxygenase-1 (HO-1), quinone oxidoreductase 1 (NQO1), and superoxide dismutase (SOD). We then used Nrf2^-/- mice to test the protective effect of Nrf2 during ISL treatment of SAP. Our results indicated that Nrf2^-/- mice had greater pancreatic injury and intestinal dysfunction than wild-type mice. They also had reduced adherens junctions (P120-catenin) and tight junctions (occludin), and increased activated nuclear factor-κB (NF-κB) protein. In Nrf2^-/- mice, ISL was less effective at these functions than in the WT mice. In conclusion, this study demonstrated that ISL exerts its protective effects against oxidative stress and inflammatory injury after SAP via regulation of the Nrf2/NF-κB pathway. It also showed that the efficacy of ISL in repairing the intestinal barrier damage caused by SAP is closely related to the Nrf2 protein. Our findings demonstrated that Nrf2 is an important protective factor against SAP-induced injuries in the pancreas and intestines.

Mechanisms of Triptolide-Induced Hepatotoxicity and Protective Effect of Combined Use of Isoliquiritigenin: Possible Roles of Nrf2 and Hepatic Transporters

Triptolide (TP), the main bioactive component of Tripterygium wilfordii Hook F, can cause severe hepatotoxicity. Isoliquiritigenin (ISL) has been reported to be able to protect against TP-induced liver injury, but the mechanisms are not fully elucidated. This study aims to explore the role of nuclear transcription factor E2-related factor 2 (Nrf2) and hepatic transporters in TP-induced hepatotoxicity and the reversal protective effect of ISL. TP treatment caused both cytotoxicity in L02 hepatocytes and acute liver injury in mice. Particularly, TP led to the disorder of bile acid (BA) profiles in mice livers. Combined treatment of TP with ISL effectively alleviated TP-induced hepatotoxicity. Furthermore, ISL pretreatment enhanced Nrf2 expressions and nuclear accumulations and its downstream NAD(P)H: quinine oxidoreductase 1 (NQO1) expression. Expressions of hepatic P-gp, MRP2, MRP4, bile salt export pump, and OATP2 were also induced. In addition, in vitro transport assays identified that neither was TP exported by MRP2, OATP1B1, or OATP1B3, nor did TP influence the transport activities of P-gp or MRP2. All these results indicate that ISL may reduce the hepatic oxidative stress and hepatic accumulations of both endogenous BAs and exogenous TP as well as its metabolites by enhancing the expressions of Nrf2, NQO1, and hepatic influx and efflux transporters. Effects of TP on hepatic transporters are mainly at the transcriptional levels, and changes of hepatic BA profiles are very important in the mechanisms of TP-induced hepatotoxicity.

Doxorubicin Has Dose-Dependent Toxicity on Mouse Ovarian Follicle Development, Hormone Secretion, and Oocyte Maturation

Doxorubicin (DOX), one of the most commonly used anticancer medications, has been reported to affect fertility by damaging ovarian follicles; however, the dose-dependent toxicity of DOX on the dynamic follicle development and oocyte maturation has not been well-defined. Our objective is to determine the effects of human-relevant exposure levels of DOX on follicular functions across developmental time. In vitro cultured multilayered secondary mouse follicles were treated with DOX at 0, 2, 20, 100, and 200 nM for 24 h, and follicle development, hormone secretion, and oocyte maturation were analyzed. DOX caused dose-dependent toxicity on follicle growth, survival, and secretion of 17β-estradiol (E2). At 200 nM, DOX induced DNA damage and apoptosis in follicle somatic cells first and then in oocytes, which was correlated with the uptake of DOX first to the somatic cells followed by germ cells. Follicles treated with DOX at 0, 2, and 20 nM showed similar oocyte metaphase II (MII) percentages after in vitro oocyte maturation; however, 20 nM DOX significantly increased the number of MII oocytes with abnormal spindle morphology and chromosome misalignment. In an effort to harmonize the in vitro study to in vivo treatment, dose-dependent toxicity on oocyte meiotic maturation was found in 16-day-old CD-1 mice treated with DOX at 0, 0.4, 2, and 10 mg/kg, consistent with the in vitro oocyte maturation outcomes. Our study demonstrates that DOX has dose-dependent toxicity on ovarian follicle development, hormone secretion, and oocyte maturation, which are three key factors to support the female reproductive and endocrine functions.

High diluted and dynamised follicle stimulating hormone modulates steroid production in isolated porcine preantral follicles cultured in vitro

Objective: This study investigated the effect of two different follicle stimulating hormone (FSH) preparations (diluted/dynamised and diluted) on the in vitro development and steroid production (estradiol, progesterone and testosterone) of isolated porcine preantral follicle after in vitro culture.

Methods: Secondary follicles were cultured in Alpha Minimum Essential Medium (α-MEM+) supplemented with grain ethanol (AL – 0.2%, v/v), diluted/dynamised FSH (rFSH 6cH – 0.05 fg/mL) or diluted-only FSH (1.5 ng/mL) for 4 days. Follicle development was evaluated on the basis of follicular growth, morphology and hormone production.

Results: The percentage of follicular integrity and extrusion were not affected by the treatments after culture. For all treatments, follicular diameter increased significantly from Day 0 to Day 4. On Day 2 of culture, the estradiol production was significantly higher in AL and diluted-only FSH treatments compared with diluted/dynamised FSH. However, diluted/dynamised FSH showed a significantly higher progesterone production on Day 2. Only on Day 4, the testosterone production was higher in the AL than diluted-only FSH treatments, but similar to diluted/dynamised FSH treatment. Except for diluted/dynamised FSH treatment, progesterone production increased (P < 0.05) from Day 2 to Day 4; only for AL treatment, a significant increase of testosterone production was observed during culture.

Conclusion: Compared to control the diluted/dynamised FSH addition increased progesterone production but decreased the estradiol production after in vitro culture of isolated porcine preantral follicles. Taken together the results suggest that at least for progesterone production the mechanism of action of diluted/dynamised FSH differs from its vehicle.