Metformin improves ovarian insulin signaling alterations caused by fetal programming.

Insulin resistance is the decreased ability of insulin to mediate metabolic actions. In the ovary, insulin controls ovulation and oocyte quality. Alterations in ovarian insulin signaling pathway could compromise ovarian physiology. Here, we aimed to investigate the effects of fetal programming on ovarian insulin signaling and evaluate the effect of metformin treatment. Pregnant rats were hyperandrogenized with testosterone and female offspring born to those dams were employed; at adulthood, prenatally hyperandrogenized (PH) offspring presented two phenotypes: irregular ovulatory (PHiov) and anovulatory (PHanov). Half of each group was orally treated with metformin. Metformin treatment improved the estrous cyclicity in both PH groups. Both PH groups showed low mRNA levels of IR, IRS1 and Glut4. IRS2 was decreased only in PHanov. Metformin upregulated the mRNA levels of some of the mediators studied. Protein expression of IR, IRS1/2 and GLUT4 was decreased in both PH groups. In PHiov, metformin restored the expression of all the mediators, whereas, in PHanov, metformin restored only that of IR and IRS1/2. IRS1 phosphorylation was measured in tyrosine residues, which activates the pathway, and in serine residues, which impairs insulin action. PHiov presented high IRS1 phosphorylation on tyrosine and serine residues, whereas PHanov showed high serine phosphorylation and low tyrosine phosphorylation. Metformin treatment lowered serine phosphorylation only in PHanov rats. Our results suggest that PHanov rats have a defective insulin action, partially restored with metformin. PHiov rats had less severe alterations, and metformin treatment was more effective in this phenotype.

Treatment with the synthetic PPARG ligand pioglitazone ameliorates early ovarian alterations induced by dehydroepiandrosterone in prepubertal rats.

BACKGROUND: Peroxisome proliferator-activated receptor gamma (PPARG) is a nuclear factor that may act on the early development of ovarian follicles and on follicular steroidogenesis. However, the exact mechanism of PPARG action remains unknown. We have previously found that androgen excess alters early ovarian function and the PPARG system. The aim of the present study was to evaluate whether PPARG activation (using the synthetic ligand pioglitazone (PGZ)) ameliorates the alterations in early ovarian function induced by androgen excess. METHODS: Female prepubertal rats were treated with equine chorionic gonadotropin (eCG) to induce folliculogenesis, together with dehydroepiandrosterone (DHEA) to induce hyperandrogenism and/or PGZ to evaluate PPARG activation. We assessed i) very early ovarian folliculogenesis, ii) PPARG activation, iii) ovarian steroidogenic enzymes, iv) the estradiol/testosterone ratio, v) the ovarian inflammatory status and vi) oxidative stress. RESULTS: PGZ prevented the inactivation of ovarian PPARG induced by androgen excess by increasing PPARG itself and the gene expression of PPARG-coactivator 1 alpha (PGC1A), and by decreasing the gene expression of nuclear co-repressor (NCOR). PGZ also prevented the altered ovarian steroidogenesis, pro-inflammatory status and oxidative stress induced by androgen excess. CONCLUSIONS: Our findings suggest that PPARG activation plays important roles in modulating early ovarian function, and highlight the importance of understanding the role(s) of PPARG activation in the ovary, and the possible involvement in the treatment of ovarian pathologies, and/or the impact in regulating/improving fertility.

Effect of hyperandrogenism on ovarian function.

The objective of this work was to study the ovarian function when follicular development is induced during a hyperandrogenic condition. Female rats were injected with either equine chorionic gonadotropin (eCG group) to induce folliculogenesis or eCG together with DHEA to induce folliculogenesis in a hyperandrogenic condition (eCG+HA group). The control group was injected with vehicle. Ovarian mRNA levels of the peroxisome proliferator-activated receptor gamma (PPARγ) co-activator PGC1α, the PPARγ co-repressor NCoR, the main enzymes involved in the ovarian steroidogenesis (CYP17, 3ß-hydroxysteroid dehydrogenase (3ß-HSD), 17ß-HSD, and CYP19A), and cyclooxygenase 2 (COX2) were evaluated only by real-time PCR. COX2 was evaluated by both real-time PCR and western blot. Serum steroid hormones and both the oxidative and inflammatory statuses were also quantified. We found that eCG-induced folliculogenesis induced increased mRNA levels of PGC1α and decreased those of NCoR when compared with controls. In addition, we found an increase in serum estradiol (E2) levels and enhanced mRNA expression of CYP19A. A pro-inflammatory status and a pro-oxidant status were also established. When folliculogenesis was induced in a hyperandrogenic condition, the mRNA levels of the PPARγ co-repressor NCoR remained higher than in controls and the pro-inflammatory and pro-oxidant statuses were enhanced. In addition, the enzymes involved in ovarian steroidogenesis were altered leading to the accumulation of testosterone and an unfavorable E2/testosterone ratio. These alterations led to abnormal follicular development.

Prenatal hyperandrogenism and lipid profile during different age stages: an experimental study.

OBJECTIVE: The present study investigates the effect of prenatal hyperandrogenization on lipid metabolism and oxidant/antioxidant balance. DESIGN: Experimental study. SETTING: Research institute. ANIMAL(S): Pregnant Sprague Dawley rats were subcutaneously injected with 2 mg free T between days 16 and 19 of pregnancy, and controls (C) received vehicle (0.1 mL of sesame oil). Prenatally hyperandrogenized female offspring (T2) had a condition that resembles polycystic ovary (PCO). Animals were weighed and killed at 21 and 60 days of age (N = 15 rats/group). INTERVENTION(S): Ovarian tissue and truncal blood were obtained from the C and T2 groups. MAIN OUTCOME MEASURE(S): Circulating lipid profile (total cholesterol, high-density lipoprotein [HDL], low-density lipoprotein [LDL] cholesterol, and triglycerides) was quantified by colorimetric-enzymatic methods. Ovarian oxidative stress was evaluated by quantifying lipid peroxidation and glutathione content by spectofotometric assays. Ovarian fat content was evaluated by Red Oil staining and ovarian messenger RNA (mRNA) expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) by real-time polymerase chain reaction (PCR). RESULT(S): At 60 days of age, 100% of group C rats and 20% of group T2 rats ovulated. At 21 days of age the T2 rats displayed lower body weight than C rats; however, at 60 days of age T2 and C rats showed similar body weights. The lipid profile (total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides) was altered in the anovulatory and ovulatory phenotype of the T2 group, but the levels were higher in the anovulatory phenotype. Lipid peroxidation of rats at 21 and 60 days of age from T2 was similar to C but the antioxidant glutathione level was decreased in 21-day-old rats compared with C rats. The lipid content of ovarian tissue, determined by Red Oil staining, was higher in the T2 than in the C group. The mRNA expression of ovarian PPAR-γ, quantified by real time PCR, decreased in anovulatory rats at 60 days of age from T2 compared to C rats. CONCLUSION(S): Our findings reveal the importance of evaluating the complete lipid profile, especially at early stages of life after the prenatal hyperandrogenism condition. In addition, we demonstrated that the antioxidant-reduced glutathione would represent a good marker of oxidative stress as it is altered before lipid peroxidation. Prenatal hyperandrogenization also alters the gene expression of PPAR-γ in rats. Here we demonstrated for the first time that abnormalities in PPAR-γ and lipid profile were higher in rats showing an anovulatory phenotype than those displaying an ovulatory phenotype.

[The role of prenatal hyperandrogenism on lipid metabolism during adult life in a rat model]. / Hiperandrogenización prenatal en ratas y el metabolismo lipídico en la vida adulta.

Polycystic ovary syndrome (PCOS) is one of the commonest endocrine diseases that affect women in their reproductive ages; however, the etiology of the syndrome remains unknown. A hypothesis proposes that during gestation increased exposure of androgen would induce fetal programming that may increase the risk of PCOS development during the adult life. By means of a prenatally hyperandrogenized (HA) rat model we demonstrated the importance of determining the lipid profile at early ages. HA induced two different phenotypes: ovulatory and anovulatory PCOS. HA did not modify total cholesterol but decreased HDL cholesterol and increased both LDL and tryglicerides (TG) when compared with controls. Both, the ratio total cholesterol: HDL (marker of cardiovascular risk) and TG:HDL (marker of metabolic syndrome) were increased in the HA group with respect to controls. In addition, these abnormalities were stronger in the anovulatory than ovulatory phenotype. Our results point out the need to find early markers of PCOS in girls or adolescents with increased risk to develop PCOS (as in daughters of women with PCOS).

Hiperandrogenización prenatal en ratas y el metabolismo lipídico en la vida adulta / The role of prenatal hyperandrogenism on lipid metabolism during adult life in a rat model

El síndrome del ovario poliquístico (PCOS) es una afección de alta incidencia en mujeres en edad fértil. Si bien la etiología de la enfermedad se desconoce, se cree que la exposición a andrógenos durante la vida intrauterina generaría reprogramación fetal afectando vías endocrinas y metabólicas que, junto a alteraciones génicas y ambientales, inducirían la aparición de PCOS en etapas muy tempranas de la vida. Es por ello que se buscan marcadores tempranos del desarrollo de PCOS. Utilizando un modelo murino de hiperandrogenización prenatal (HA) recreamos dos fenotipos de PCOS: ovulatorio y anovulatorio. La HA no alteró el colesterol circulante pero disminuyó el colesterol HDL y aumentó el LDL y los triglicéridos (TG) con respecto a los controles. La relación colesterol total/HDL como marcador de riesgo cardiovascular y la relación TG/HDL se vieron incrementadas con respecto a los controles, resultando mayor en el grupo PCOS anovulatorio. El presente trabajo demuestra la importancia de la determinación del perfil lipídico a edades tempranas en poblaciones de riesgo (como es el caso de hijas de madres con PCOS).

Polycystic ovary syndrome (PCOS) is one of the commonest endocrine diseases that affect women in their reproductive ages; however, the etiology of the syndrome remains unknown. A hypothesis proposes that during gestation increased exposure of androgen would induce fetal programming that may increase the risk of PCOS development during the adult life. By means of a prenatally hyperandrogenized (HA) rat model we demonstrated the importance of determining the lipid profile at early ages. HA induced two different phenotypes: ovulatory and anovulatory PCOS. HA did not modify total cholesterol but decreased HDL cholesterol and increased both LDL and tryglicerides (TG) when compared with controls. Both, the ratio total cholesterol: HDL (marker of cardiovascular risk) and TG:HDL (marker of metabolic syndrome) were increased in the HA group with respect to controls. In addition, these abnormalities were stronger in the anovulatory than ovulatory phenotype. Our results point out the need to find early markers of PCOS in girls or adolescents with increased risk to develop PCOS (as in daughters of women with PCOS).

Hiperandrogenización prenatal en ratas y el metabolismo lipídico en la vida adulta / The role of prenatal hyperandrogenism on lipid metabolism during adult life in a rat model

El síndrome del ovario poliquístico (PCOS) es una afección de alta incidencia en mujeres en edad fértil. Si bien la etiología de la enfermedad se desconoce, se cree que la exposición a andrógenos durante la vida intrauterina generaría reprogramación fetal afectando vías endocrinas y metabólicas que, junto a alteraciones génicas y ambientales, inducirían la aparición de PCOS en etapas muy tempranas de la vida. Es por ello que se buscan marcadores tempranos del desarrollo de PCOS. Utilizando un modelo murino de hiperandrogenización prenatal (HA) recreamos dos fenotipos de PCOS: ovulatorio y anovulatorio. La HA no alteró el colesterol circulante pero disminuyó el colesterol HDL y aumentó el LDL y los triglicéridos (TG) con respecto a los controles. La relación colesterol total/HDL como marcador de riesgo cardiovascular y la relación TG/HDL se vieron incrementadas con respecto a los controles, resultando mayor en el grupo PCOS anovulatorio. El presente trabajo demuestra la importancia de la determinación del perfil lipídico a edades tempranas en poblaciones de riesgo (como es el caso de hijas de madres con PCOS).(AU)

Polycystic ovary syndrome (PCOS) is one of the commonest endocrine diseases that affect women in their reproductive ages; however, the etiology of the syndrome remains unknown. A hypothesis proposes that during gestation increased exposure of androgen would induce fetal programming that may increase the risk of PCOS development during the adult life. By means of a prenatally hyperandrogenized (HA) rat model we demonstrated the importance of determining the lipid profile at early ages. HA induced two different phenotypes: ovulatory and anovulatory PCOS. HA did not modify total cholesterol but decreased HDL cholesterol and increased both LDL and tryglicerides (TG) when compared with controls. Both, the ratio total cholesterol: HDL (marker of cardiovascular risk) and TG:HDL (marker of metabolic syndrome) were increased in the HA group with respect to controls. In addition, these abnormalities were stronger in the anovulatory than ovulatory phenotype. Our results point out the need to find early markers of PCOS in girls or adolescents with increased risk to develop PCOS (as in daughters of women with PCOS).(AU)