Epigallocatechin-3-gallate attenuates cyclophosphamide-induced damage in mouse ovarian tissue via suppressing inflammation, apoptosis, and expression of phosphorylated Akt, FOXO3a and rpS6

This study was conducted to evaluate the protective effects of epigallocatechin-3-gallate (EGCG) against ovarian toxicity in cyclophosphamide-treated mice and to verify the possible involvement of phosphorylated Akt, FOXO3a and rpS6 in the EGCG actions. Mice received saline solution (i.p.; control) or a single dose of cyclophosphamide (200 mg/kg body weight, i.p.) or mice were pretreated with N-acetylcysteine (150 mg/kg body weight, i.p.; positive control) or with EGCG (5, 25 or 50 mg/kg body weight, i.p.) once daily for three days followed by injection with single dose of cyclophosphamide (200 mg/kg body weight, i.p.). Thereafter, the mice were euthanized, and the ovaries were harvested and destined to histological (follicular morphology and activation), immunohistochemistry (cleaved caspase-3 and TNF-α) and fluorescence (mitochondrial activity and GSH concentrations) analyses. Furthermore, we examined the participation of p-Akt, p-FOXO3a and p-rpS6 in the protective effects of EGCG in cyclophosphamide-induced ovarian damage by immunohistochemical staining. The results showed that pretreatment with N-acetylcysteine or EGCG at 25 and 50 mg/kg before cyclophosphamide administration preserved the normal follicular morphology, prevented primordial follicle loss, reduced atresia, inflammation, and mitochondrial damage, and increased GSH concentrations compared to the only cyclophosphamide treatment. Additionally, pretreatment with 25 mg/kg EGCG regulated phosphorylated Akt, FOXO3a and rpS6 after cyclophosphamide treatment. In conclusion, short-time pretreatment with 25 mg/kg EGCG can prevent follicle loss in cyclophosphamide-treated mice by reducing oxidative damage, inflammation, and apoptosis, and regulating of p-Akt, p-FOXO3a and p-rpS6.

Immunolocalization of melatonin receptor type 1 in the sheep ovary and involvement of the PI3K/Akt/FOXO3a signaling pathway in the effects of melatonin on survival and in vitro activation of primordial follicles

This study characterized the expression of melatonin receptor type 1 (MT₁ ) protein in sheep ovaries, evaluated melatonin effects on primordial follicle survival and development after in vitro culture of ovarian tissue and verified the possible involvement of the phosphatidylinositol-3-kinase/protein kinase B/forkhead box O3a (PI3K/Akt/FOXO3a) pathway in the melatonin actions. Ovine ovarian fragments were cultured in α-modified minimum essential medium alone (α-MEM⁺ ) or supplemented with 100, 500, or 1000 pg/ml melatonin for 7 days. PI3K inhibition was performed through pretreatment of ovarian fragments with LY294002. Thereafter, immunohistochemistry was performed to evaluate the expression of cleaved caspase-3, Akt, phosphorylated-Akt, and phosphorylated-FOXO3a (p-FOXO3a). The immunohistochemical localization of the MT₁ receptor protein was documented in sheep preantral and antral follicles. After in vitro culture, 100 pg/ml melatonin showed higher follicular survival and activation than α-MEM⁺ and other melatonin concentrations. After PI3K inhibition, there was an increase in cleaved caspase-3-positive follicles, and a decrease in the primordial follicle activation, Akt phosphorylation, and nuclear exclusion of p-FOXO3a. In conclusion, MT₁ receptor protein is present in the sheep ovary. Furthermore, 100 pg/ml melatonin maintains survival and stimulates activation of primordial follicles through the PI3K/Akt/FOXO3a signaling pathway after in vitro culture of sheep ovarian tissue.

Protective Effects of Antioxidants on Cyclophosphamide-Induced Ovarian Toxicity

The most common limitation of anticancer chemotherapy is the injury to normal cells. Cyclophosphamide, which is one of the most widely used alkylating agents, can cause premature ovarian insufficiency and infertility since the ovarian follicles are extremely sensitive to their effects. Although little information is available about the pathogenic mechanism of cyclophosphamide-induced ovarian damage, its toxicity is attributed to oxidative stress, inflammation, and apoptosis. The use of compounds with antioxidant and cytoprotective properties to protect ovarian function from deleterious effects during chemotherapy would be a significant advantage. Thus, this article reviews the mechanism by which cyclophosphamide exerts its toxic effects on the different cellular components of the ovary, and describes 24 cytoprotective compounds used to ameliorate cyclophosphamide-induced ovarian injury and their possible mechanisms of action. Understanding these mechanisms is essential for the development of efficient and targeted pharmacological complementary therapies that could protect and prolong female fertility.

Amburana cearensis leaf extract protects against cisplatin-induced ovarian damage through regulation of p-PTEN and p-Akt proteins in mice

Objectives

To evaluate the effects of Amburana cearensis leaf extract against cisplatin-induced ovarian toxicity in mice and involvement of p-PTEN and p-Akt proteins.

Materials and Methods

A. cearensis ethanolic leaf extract was analyzed by high-performance liquid chromatography (HPLC). Mice were pretreated once daily for 3 days as follows: (1) the control group was pretreated with oral administration (o.p.) of saline solution, followed by intraperitoneal (IP) injection of saline solution. The other groups were pretreated (o.p.) with (2) saline solution (cisplatin group), (3) N-acetylcysteine (positive control), with (4) 50, or (5) 200 mg/kg body weight of A. cearensis extract, followed by injection of 5 mg/kg body weight (IP) of cisplatin. The ovaries were harvested and destined for histological (follicular morphology), immunohistochemistry (apoptosis and cell proliferation), and fluorescence (reactive oxygen species [ROS], glutathione concentrations [GSH], and active mitochondria) analyses. Furthermore, immunoexpression of p-PTEN and p-Akt was evaluated to elucidate a potential mechanism by which A. cearensis extract could prevent cisplatin-induced ovarian damage.

Results

After HPLC analysis, protocatechuic acid was detected in the extract. The pretreatment with N-acetylcysteine or A. cearensis extract maintained the percentage of normal follicles and cell proliferation, reduced apoptosis and ROS concentrations, and increased GSH concentrations and mitochondrial activity compared with cisplatin treatment. Furthermore, pretreatment with A. cearensis extract regulated p-PTEN and p-Akt immunoexpression after cisplatin exposure.

Conclusion

Pretreatment with A. cearensis extract prevented cisplatin-induced ovarian damage through its anti-oxidant actions and by modulating the expression of phosphorylated PTEN and Akt proteins.

Rutin promotes activation and reduces apoptosis of primordial follicles by regulating Akt phosphorylation after in vitro culture of ovine ovarian tissue

The aims of this study were to analyze the effects of different concentrations of rutin on primordial follicle survival and development after in vitro culture of sheep ovarian tissue, and to verify the possible involvement of the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) pathway in the rutin actions. Ovarian fragments were fixed for histological analysis (fresh control) or cultured in α-minimum essential medium alone (α-MEM⁺: control medium) or in α-MEM⁺supplemented with different concentrations of rutin (0.1; 1 or 10 μg/mL) for 7 days. Inhibition of the PI3K activity was performed in fragments cultured with 50 μM LY294002. Thereafter, immunohistochemistry was performed to evaluate the expression of cleaved caspase-3 (apoptosis) and Akt phosphorylation (p-Akt). The results showed that 1 μg/mL rutin has a greater percentage of normal follicles (P < 0.05) than those of α-MEM⁺ and other rutin treatments. In addition, 1 μg/mL rutin maintained the follicular apoptosis similar (P > 0.05) to that of the fresh control and lower than α-MEM⁺ and 10 μg/mL rutin. All rutin concentrations increased (P < 0.05) follicular activation compared to fresh control and α-MEM⁺. Furthermore, follicular and oocyte diameters increased (P < 0.05) only after culture with 1 μg/mL rutin. After PI3K inhibition, there was a reduction (P < 0.05) of rutin follicular effects. In conclusion, rutin at 1 μg/mL reduces apoptosis, promotes activation and growth of sheep primordial follicles through the modulation of the PI3K/Akt signaling pathway after in vitro culture of ovine ovarian tissue.

Gallic acid promotes the in vitro development of sheep secondary isolated follicles involving the phosphatidylinositol 3-kinase pathway

This study was conducted to evaluate the effect of addition of gallic acid as the single antioxidant to the base medium for in vitro culture of sheep secondary follicles and if the phosphatidylinositol 3-kinase (PI3K) pathway is involved in the action of gallic acid. Secondary follicles were isolated and cultured for 12 days in α-MEM supplemented with bovine serum albumin (BSA), insulin, glutamine, hypoxanthine, transferrin, selenium, and ascorbic acid (control medium: α-MEM⁺) or in α-MEM supplemented with BSA, insulin, glutamine, hypoxanthine and different concentrations of gallic acid (25, 50 or 100 μM), thus replacing transferrin, selenium and ascorbic acid in the medium. Follicle morphology, glutathione (GSH), and mitochondrial activity, and meiotic resumption were evaluated. Furthermore, inhibition of PI3K pathway was performed by pretreatment with LY294002. After 12 days of culture, the follicle survival in a medium containing 100 μM gallic acid was similar (P > 0.05) to α-MEM⁺ and greater (P < 0.05) compared with other gallic acid concentrations. Antrum formation, follicle diameter, GSH, and mitochondrial activity, and meiotic resumption, however, were greater (P < 0.05) when 100 μM gallic acid was included in the α-MEM⁺ culture medium compared with the control medium. Furthermore, LY294002 inhibited (P < 0.05) follicle survival, development, and meiotic resumption stimulated by 100 μM gallic acid. In conclusion, concentration of 100 μM of gallic acid can be a substitute for transferrin, selenium, and ascorbic acid in the base medium during in vitro culture of sheep secondary follicles, inducing follicle development likely through the PI3K pathway.

Rutin prevents cisplatin-induced ovarian damage via antioxidant activity and regulation of PTEN and FOXO3a phosphorylation in mouse model

The aims of the present study were to evaluate the protective effects of rutin during cisplatin-induced ovarian toxicity in mice and to verify the possible involvement of the phosphatase and tension homolog (PTEN)/Forkhead box O3a (FOXO3a) pathway in the rutin actions. Mice received saline solution (control, 0.15 M, i.p.) or cisplatin (5 mg/Kg body weight, i.p.) or they were pretreated with N-acetylcysteine (positive control; 150 mg/Kg of body weight [p.o.]) or with rutin (10, 30 or 50 mg/Kg body weight, p.o.) before cisplatin (5 mg/Kg body weight, i.p.) once daily for 3 days. Next, the ovaries were harvested and destined to histological (follicular morphology and activation), immunohistochemical (cell proliferation and apoptosis) and fluorescence (reactive oxygen species [ROS], glutathione [GSH] and mitochondrial activity) analyses. Moreover, the expression of phosphorylated PTEN (p-PTEN) and FOXO3a (p-FOXO3a) were evaluated to investigate a molecular mechanism by which rutin would prevent the cisplatin-induced ovarian damage. The results showed that pretreatment with N-acetylcysteine or 10 mg/Kg rutin before cisplatin preserved the percentage of normal follicles and cell proliferation, reduced apoptosis and ROS levels and increased active mitochondria and GSH levels compared to the cisplatin treatment (P < 0.05). Cisplatin treatment increased p-PTEN and decreased p-FOXO3a expression in follicles, which was prevented by 10 mg/kg rutin. In conclusion, treatment with 10 mg/Kg rutin has the potential to protect the ovarian follicles against cisplatin-induced toxicity through its antioxidant effects and PTEN/FOXO3a pathway.

Epigallocatechin-3-gallate (EGCG) reduces apoptosis of preantral follicles through the phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) signaling pathway after in vitro culture of sheep ovarian tissue

The aims of this study were to analyze the effects of different concentrations of epigallocatechin-3-gallate (EGCG) on the primordial follicle survival and development after in vitro culture of ovarian tissue, and to verify the possible involvement of the phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathway in the EGCG actions in the sheep ovary. Ovarian fragments were fixed for histological analysis (fresh control) or cultured in α-minimum essential medium alone (α-MEM⁺: control medium) or with different concentrations of EGCG (0.01; 0.1; 1; 10 or 100 μg/mL) for 7 days. Inhibition of PI3K activity was performed in fragments cultured with 1 μg/mL EGCG plus LY294002. Thereafter, immunohistochemistry was performed to evaluate the expression of cleaved caspase-3 and AKT phosphorylation (p-AKT). The results showed that 1 μg/mL EGCG maintained the follicular survival similar (P > 0.05) to that of the fresh control and higher (P < 0.05) than that of the α-MEM⁺ and other EGCG treatments. No difference (P > 0.05) in the follicular activation was observed. However, both follicle and oocyte diameters increased after in vitro culture with 1 μg/mL EGCG compared to other treatments (P < 0.05), except for 10 μg/mL EGCG (P > 0.05). After PI3K inhibition, there was an increase (P < 0.05) of the follicular apoptosis and a reduction of p-AKT immunolocalization. In conclusion, EGCG at 1 μg/mL reduces apoptosis of preantral follicles through the PI3K/AKT pathway after in vitro culture of sheep ovarian tissue.

Effects of melatonin on the in vitro growth of early antral follicles and maturation of ovine oocytes

This study aimed to evaluate the effect of melatonin on the in vitro culture and maturation of isolated sheep early antral follicles. Isolated early antral follicles were cultured for 12 d in α-minimum essential medium (MEM⁺) alone (control) or α-MEM⁺ added with fixed different concentrations (100, 500, or 1,000 pg/mL) or a sequential concentration of melatonin (MelSeq; day 6 = 100; day 12 = 500 pg/mL). The percentage of morphologically normal follicles was higher (P < 0.05) in 500 pg/mL melatonin than the other treatments at 6 d. Mel 500 also showed a higher rate of fully grown oocytes (P < 0.05) than other treatments. After in vitro culture, reactive oxygen species (ROS) levels in oocytes were similar between Mel 500 and MelSeq, with both being lower (P < 0.05) than other treatments. Oocytes cultured in both Mel 500 and Mel 1000 showed glutathione peroxidase levels similar (P > 0.05) to the control group and higher (P < 0.05) than other treatments. Mitochondrial activity was similar (P > 0.05) among control, Mel 500, and Mel 1000 treatments. Mel 500 treatment presented a higher percentage of germinal vesicle breakdown oocytes than the control group and similar percentages to the other treatments. Follicles cultured in melatonin followed by oocyte maturation with the addition of 500 pg/mL melatonin in maturation medium showed increased (P < 0.05) levels of mitochondrial activity compared to α-MEM⁺ alone. In conclusion, the concentration of 500 pg/mL of melatonin promotes development and decreases ROS levels of ovine oocytes from in vitro grown early antral follicles. Moreover, melatonin increases mitochondrial activity and promotes the acquisition of meiotic competence of these oocytes.

Insulin-like growth factor-1 (IGF-1) promotes primordial follicle growth and reduces DNA fragmentation through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signalling pathway

We investigated the effects of insulin-like growth factor 1 (IGF-1) on the morphology and follicular activation of ovine preantral follicles cultured in situ and whether the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway is involved in IGF-1 action in the sheep ovary. Ovine ovarian fragments were fixed for histological and terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) analyses (fresh control) or cultured in supplemented alpha-minimum essential medium (α-MEM+; control) or α-MEM+ with IGF-1 (1, 10, 50, 100 or 200ngmL-1) for 7 days. Follicles were classified as normal or atretic, primordial or growing and the oocyte and follicle diameters were measured. DNA fragmentation was evaluated by TUNEL assay. Proliferating cell nuclear antigen (PCNA) immunohistochemistry was performed on the fresh control, α-MEM+ and 100ngmL-1 IGF-1 samples. Inhibition of PI3K activity was performed through pretreatment with the PI3K inhibitor LY294002 and phosphorylated AKT (pAKT) expression was analysed after culture in the absence or presence of LY294002. IGF-1 at 100ngmL-1 increased (P<0.05) follicular activation compared with α-MEM+ and decreased TUNEL-positive cells (P<0.05) compared with other treatments. PCNA-positive cells also increased (P<0.05) in 100ngmL-1 IGF-1. LY294002 significantly inhibited follicular activation stimulated by α-MEM+ and 100ngmL-1 IGF-1 and reduced pAKT expression in follicles. Overall, IGF-1 at 100ngmL-1 promoted primordial follicle activation, cell proliferation and reduced DNA fragmentation after in situ culture through the PI3K/AKT pathway.

Immunolocalization of leptin and its receptor in the sheep ovary and in vitro effect of leptin on follicular development and oocyte maturation

The aims of the study were to characterize leptin and it is receptor (LEPR) proteins immunoexpression in ovine ovaries and to evaluate the effects of leptin on development of secondary follicles cultured in vitro. The ovaries were collected and fixed for immunohistochemical analysis. Additional pairs of ovaries were collected and secondary follicles were isolated and cultured, for 18 days, in α-MEM⁺ alone or supplemented with 10 or 25 ng/mL of leptin. The antrum formation and fully grown oocytes rates were higher in 25 ng/mL leptin than all treatments. GSH levels and mitochondrial activity were higher in 10 or 25 ng/mL leptin than α-MEM⁺. 25 ng/mL leptin showed a higher percentage of MII than the α-MEM⁺. In conclusion, leptin and its receptor are expressed in ovine ovaries and 25 ng/mL leptin promoted higher in vitro maturation rates by improving follicular development, GSH levels and mitochondrial activity of ovine oocytes compared to control medium.

Effects of leptin on the follicular development and mitochondrial activity of ovine isolated early antral follicles cultured in vitro

This study evaluated the effect of leptin on the in vitro culture of isolated sheep early antral follicles. Early antral follicles (300-450 μm) were isolated and cultured for 12 days in tissue culture medium 199 (TCM 199) supplemented with glutamine, hypoxanthine, transferrin, insulin, selenium, ascorbic acid, bovine serum albumin (BSA) and recombinant follicle stimulating hormone (rFSH) (TCM 199⁺: control medium) or TCM 199⁺ supplemented with 2 or 10 ng/mL leptin. After culture, oocytes were subjected to in vitro maturation (IVM). The parameters analyzed were morphology, extrusion rate, follicular diameter, growth and fully-grown oocytes (oocytes ≥110 μm) rates. After IVM, reactive oxygen species (ROS) levels, mitochondrial activity, meiotic stages and meiotic resumption rates were also analyzed. After 12 days of culture, the concentration of 2 ng/mL of leptin showed a higher percentage of morphologically normal follicles, fully-grown oocytes (≥110 μm), active mitochondria and meiotic resumption compared to the control medium (TCM 199⁺; P < 0.05) but did not differ when compared to leptin concentration of 10 ng/mL (P > 0.05). After culturing, no significant differences existed among treatments in terms of the follicle diameter and ROS levels. In conclusion, the addition of 2 ng/mL leptin to the base culture medium is capable of improving follicular survival, oocyte growth, mitochondrial activity and meiotic resumption after the in vitro culture of isolated sheep early antral follicles.

Growth differentiation factor-9 improves development, mitochondrial activity and meiotic resumption of sheep oocytes after in vitro culture of secondary follicles

This study analysed the effect of growth differentiation factor-9 (GDF-9) on the in vitro culture of isolated ovine secondary follicles. The follicles were cultured in α-MEM supplemented with BSA, insulin, glutamine, hypoxanthine, transferrin, selenium, ascorbic acid and FSH (α-MEM⁺ -control medium) or α-MEM⁺ supplemented with 1, 10, 50 or 100 ng/ml GDF-9. Next, the oocytes were destined to in vitro maturation (IVM). After 12 days of culture, there were no differences regarding the percentage of normal follicles, antrum formation and follicle diameter between the treatments (p > 0.05). The rates of fully grown oocytes (≥110 µm) were higher (p < 0.05) in 100 ng/ml GDF-9 than other treatments, except for 10 ng/ml of GDF-9 (p > 0.05). Treatment containing 100 ng/ml GDF-9 showed higher (p < 0.05) mitochondrial activity than the control group. Moreover, 100 ng/ml GDF-9 showed more oocytes in MI than α-MEM⁺ , 1 or 50 ng/ml GDF-9 (p < 0.05). In conclusion, 100 ng/ml GDF-9 increased the growth, mitochondrial function and meiotic resumption of oocytes from in vitro grown sheep secondary follicles.

Kaempferol can be used as the single antioxidant in the in vitro culture medium, stimulating sheep secondary follicle development through the phosphatidylinositol 3-kinase signaling pathway

This study evaluated the effect of addition of kaempferol alone or combined with other antioxidants (transferrin, selenium and ascorbic acid) on in vitro culture of sheep isolated secondary follicles and if PI3K pathway is involved in kaempferol action. Secondary follicles were isolated and cultured for 12 days in α-Minimal Essential Medium (α-MEM) supplemented with BSA, insulin, glutamine and hypoxanthine (α-MEM: antioxidant free-medium) or in this medium also added by transferrin, selenium and ascorbic acid (AO: base medium with antioxidants). Moreover, different concentrations of kaempferol (0.1; 1 or 10 μM) were added to the different base media (α-MEM or AO). After culture, glutathione (GSH) levels, mitochondrial activity and meiotic resumption were evaluated. In addition, inhibition of PI3K activity was performed through pretreatment in medium supplemented with LY294002. After 12 days, the percentage of normal follicles was higher (P < 0.05) in AO base medium than the other treatments and similar (P > 0.05) to α-MEM supplemented with 1 or 10 μM kaempferol Moreover, α-MEM plus 1 or 10 μM kaempferol and AO medium showed similar (P > 0.05) follicular diameter, fully-grown oocytes, and GSH levels. However, at the end of the culture, antrum formation was higher (P < 0.05) in α-MEM + 1 μM kaempferol than in AO, and similar (P > 0.05) to α-MEM + 10 μM kaempferol. In addition, oocytes cultured in α-MEM supplemented with 1 μM kaempferol showed greater (P < 0.05) levels of active mitochondria than α-MEM + 10 μM kaempferol and AO medium. The rates of meiotic resumption were similar (P > 0.05) among α-MEM + 1 μM kaempferol and AO medium. LY294002 significantly inhibited antrum formation, follicular diameter and the percentage of fully grown oocytes stimulated by 1 μM kaempferol. In conclusion, 1 μM kaempferol can be used as the single antioxidant present in the base medium, replacing the addition of transferrin, selenium and ascorbic acid during in vitro culture of ovine secondary follicles, maintaining follicular survival, increasing active mitochondria levels, and promoting the oocyte meiotic resumption. Moreover, the development of the ovine secondary follicle stimulated by kaempferol is mediated by PI3K pathway.

Resveratrol promotes in vitro activation of ovine primordial follicles by reducing DNA damage and enhancing granulosa cell proliferation via phosphatidylinositol 3-kinase pathway

We aimed to study the effects of resveratrol on the morphology, DNA fragmentation, follicular activation and cell proliferation after in vitro culture of ovine ovarian tissue, and to verify if PI3K pathway is involved in resveratrol action in the sheep ovary. Ovaries were collected and divided into fragments. One fragment was fixed for histology (fresh control). The remaining fragments were cultured for 7 days in control medium (α-MEM⁺ ) alone or with resveratrol (2, 10 or 30 µM). After culture, ovarian tissue was destined to morphological analysis. TUNEL and proliferating cell nuclear antigen (PCNA) analyses were performed in the fresh control, α-MEM⁺ and 2 µM resveratrol. Inhibition of PI3K activity was performed through pre-treatment with LY294002. The percentage of normal follicles was similar between α-MEM⁺ and 2 µM resveratrol, and higher than those in other resveratrol treatments. An increase in follicular activation was observed in all treatments compared to fresh control. DNA fragmentation decreased in tissues cultured in 2 µM resveratrol compared to α-MEM⁺ . Moreover, PCNA-positive cells were higher in 2 µM resveratrol than in α-MEM⁺ . LY294002 inhibited follicular activation stimulated by α-MEM⁺ and 2 µM resveratrol. In conclusion, 2 µM resveratrol promotes primordial follicle activation compared to the fresh control by reducing DNA fragmentation and stimulating granulosa cell proliferation through activation of the PI3K pathway.

Melatonin protects against cisplatin-induced ovarian damage in mice via the MT1 receptor and antioxidant activity

This study evaluated the receptor- and/or antioxidant stress-mediated mechanisms by which melatonin prevents the ovarian toxicity of cisplatin treatment. The expression of the MT1 receptor in mouse ovaries was investigated by immunohistochemistry. Pretreatment with melatonin (5, 10, or 20 mg/kg body weight, i.p.) before cisplatin (5 mg/kg body weight, i.p.) was administered to mice once daily for 3 days (phase I). The pharmacological modulation via melatonin type 1 and/or 2 receptors was analyzed by administration of receptor antagonists (luzindole: nonselective MT1/MT2 antagonist; 5 mg/kg body weight or 4-phenyl-2-propionamidotetralin: selective MT2 antagonist; 4 mg/kg body weight) once daily for 3 days, 15 min before the treatment with melatonin and cisplatin (phase II). Thereafter, the ovaries were harvested and used for histological (morphology and activation), immunohistochemical (PCNA, activated caspase-3 and bcl-2 expression), terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, and fluorescence (reactive oxygen species [ROS], glutathione [GSH], and active mitochondria levels) analyses. The expression of the MT1 protein in mouse ovaries was documented. Pretreatment with 20 mg/kg melatonin before cisplatin administration preserved the normal follicular morphology and cell proliferation rate, reduced apoptosis, ROS production, mitochondrial damage and increased GSH expression, as compared to the cisplatin treatment alone. Additionally, administration of the nonselective MT1/MT2 receptor antagonist inhibited the melatonin ovarian protection from the cytotoxic effects of cisplatin. However, administration of a selective MT2 antagonist did not modify the protective effects observed at 20 mg/kg melatonin. In conclusion, pretreatment with 20 mg/kg melatonin effectively protected the ovaries against cisplatin-induced damage. Moreover, the MT1 receptor and melatonin antioxidant effects mediated this cytoprotective activity.

Supplemented Morus nigra extract-based medium associated with FSH enables the survival and growth of isolated ovine secondary ovarian follicles

The effects of Morus nigra ethanolic extract, without or with addition of supplements associated or not with FSH, on in vitro culture of ovine secondary follicles were evaluated. In experiment 1, isolated secondary follicles were cultured for 12 days in α-MEM alone (control) or in different concentrations of M. nigra extract (MN 0.025; 0.05 or 0.1 mg/ml). In experiment 2, culture media were α-MEM supplemented with BSA, insulin, transferrin, selenium, glutamine, hypoxanthine and ascorbic acid (α-MEM⁺ ) or this medium associated with FSH (α-MEM⁺  + FSH), or 0.1 mg/ml M. nigra without supplements (MN 0.1) or supplemented (MN 0.1⁺ ) without or with FSH (MN 0.1⁺  + FSH). In experiment 1, 0.1 mg/ml M. nigra showed the highest percentages (p < .05) of normal follicles and fully grown oocytes, besides a higher follicular diameter than α-MEM and other M. nigra extract concentrations. Moreover, MN 0.1 showed lower (p < .05) glutathione (GSH) levels and similar (p > .05) mitochondrial activity compared to α-MEM. In experiment 2, MN 0.1⁺  + FSH showed similar results (p > .05) to α-MEM⁺  + FSH for all parameters evaluated, except for the daily growth rate, which was higher (p < .05) in MN 0.1⁺  + FSH. The GSH levels were higher in MEM⁺ than all treatments. In addition, oocytes from follicles cultured in MN 0.1⁺  + FSH showed ability to resume meiosis. In conclusion, M. nigra extract (0.1 mg/ml) added by supplements and FSH can be an efficient medium for ovine secondary follicle development.

Expression of TNF-α system members in bovine ovarian follicles and the effects of TNF-α or dexamethasone on preantral follicle survival, development and ultrastructure in vitro

This study was conducted to detect the protein expression of TNF-α system members (TNF-α/TNFR1/TNFR2) in bovine ovarian follicles and to evaluate the effects of TNF-α or dexamethasone on the survival and growth of primordial follicles in vitro, as well as on gene expression in cultured ovarian tissue. It was hypothesized that TNF-α induces follicular atresia in ovarian tissues cultured in vitro, and that dexamethasone suppresses the production of endogenous TNF-α, which can improve follicle viability in vitro. Ovarian fragments were cultured for 6days in α-MEM⁺ supplemented with TNF-α (0, 1, 10, 100 or 200ng/ml) or dexamethasone (0, 1, 10, 100 or 200ng/ml). After culture, the expression of mRNAs for BCL-2, BAX, P53, TNF-α, and CASP3 and CASP6 were evaluated. Immunohistochemical results showed that the TNF-α system members, were detected in bovine preantral and antral follicles. After 6days, the TNF-α (10ng/ml) treatment reduced the percentage of normal preantral follicles and increased the number of TUNEL-positive cells in cultured tissue. Dexamethasone (10ng/ml) during 6days of culture did maintain the percentage of normal follicles and the ultrastructure of follicles, while the presence of TNF-α or dexamethasone did not influence primordial follicle activation. However, TNF-α or dexamethasone had no effect on the levels of mRNA for P53, BCL-2, BAX and CASP6, in cultured tissues, but the presence of dexamethasone reduced the levels of CASP3 compared to ovarian slices cultured in control medium (α-MEM⁺). In conclusion, proteins of the TNF-α system are expressed at different bovine follicle stages. The addition of TNF-α in culture reduces follicle survival and increases the number of apoptotic cells in ovarian tissue, while the presence of dexamethasone maintains follicle ultrastructure in cultured tissue.

Immunohistochemical localization of fibroblast growth factor-2 in the sheep ovary and its effects on pre-antral follicle apoptosis and development in vitro

Studies with sheep are important to improve our knowledge about the factors that control folliculogenesis in mammals and to explore possible physiological differences among species. The aims of this study were to characterize FGF-2 protein expression in ovine ovaries and to verify the effect of FGF-2 on the morphology, apoptosis and growth of ovine pre-antral follicles cultured in vitro. After collection, one fragment of ovarian tissue was fixed for histological analysis and TUNEL analysis (fresh control). The remaining fragments were cultured for 7 days in control medium (α-MEM(+) ) alone or supplemented with FGF-2 at different concentrations (1, 10, 50, 100 or 200 ng/ml). After culturing, ovarian tissue was destined to histology and TUNEL analysis, and oocyte and follicle diameters were measured. The immunostaining for FGF-2 was observed in oocytes from primordial, primary and secondary follicles, as well as in granulosa cells of secondary and antral follicles. The percentage of normal follicles was similar among control medium, 1 and 10 ng/ml FGF-2, and significantly higher than those observed in 50, 100 or 200 ng/ml FGF-2. A significant increase in follicle diameter was observed when tissues were cultured in 10, 50, 100 or 200 ng/ml FGF-2 compared with the fresh control and the other treatments. Similar results were observed for oocyte diameter in tissues cultured with 50, 100 or 200 ng/ml FGF-2 (p < 0.05). However, the percentage of apoptotic cells only decreased (p < 0.05) in ovarian tissues cultured in 1 or 10 ng/ml FGF-2 compared with the control medium and other FGF-2 treatments. In conclusion, this study demonstrated the presence of FGF-2 in ovine ovaries. Furthermore, 10 ng/ml FGF-2 inhibits apoptosis and promotes ovine follicle growth. As the sheep ovary is more similar to that of humans, the culture system demonstrated in this work seems to be an appropriate tool for studies towards human folliculogenesis.