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Cytochrome P450 1B1 (CYP1B1) has been widely associated with the development of cardiac pathologies due to its ability to produce cardiotoxic metabolites like midchain hydroxyeicosatetraenoic acids (HETEs) from arachidonic acid (AA) through an allylic oxidation reaction. 16-HETE is a subterminal HETE that is also produced by CYP-mediated AA metabolism. 19-HETE is another subterminal HETE that was found to inhibit CYP1B1 activity, lower midchain HETEs, and have cardioprotective effects. However, the effect of 16-HETE enantiomers on CYP1B1 has not yet been investigated. We hypothesized that 16(R/S)-HETE could alter the activity of CYP1B1 and other CYP enzymes. Therefore, this study was carried out to investigate the modulatory effect of 16-HETE enantiomers on CYP1B1 enzyme activity, and to examine the mechanisms by which they exert these modulatory effects. To investigate whether these effects are specific to CYP1B1, we also investigated 16-HETE modulatory effects on CYP1A2. Our results showed that 16-HETE enantiomers significantly increased CYP1B1 activity in RL-14 cells, recombinant human CYP1B1, and human liver microsomes, as seen by the significant increase in 7-ethoxyresorufin deethylation rate. On the contrary, 16-HETE enantiomers significantly inhibited CYP1A2 catalytic activity mediated by the recombinant human CYP1A2 and human liver microsomes. 16R-HETE showed stronger effects than 16S-HETE. The sigmoidal binding mode of the enzyme kinetics data demonstrated that CYP1B1 activation and CYP1A2 inhibition occurred through allosteric regulation. In conclusion, our study provides the first evidence that 16R-HETE and 16S-HETE increase CYP1B1 catalytic activity through an allosteric mechanism., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Cytochrome P450 (CYP) metabolizes arachidonic acid to produce bioactive metabolites such as EETs and HETEs: mid-chain, subterminal, and terminal HETEs. Recent studies have revealed the role of CYP1B1 and its associated cardiotoxic mid-chain HETE metabolites in developing cardiac hypertrophy and heart failure. Subterminal HETEs have also been involved in various physiological and pathophysiological processes; however, their role in cardiac hypertrophy has not been fully defined., Objective: The objective of the current study is to determine the possible effect of subterminal HETEs, R and S enantiomers of 16-HETE, on CYP1B1 expression in vitro using human cardiomyocytes RL-14 cells., Methods: In the study, RL14 cell line was treated with vehicle and either of the 16-HETE enantiomers for 24 h. Subsequently, the following markers were assessed: cell viability, cellular size, hypertrophic markers, CYP1B1 gene expression (at mRNA, protein, and activity levels), luciferase activity, and CYP1B1 mRNA and protein half-lives., Results: The results of the study showed that 16-HETE enantiomers significantly increased hypertrophic markers and upregulated CYP1B1 mRNA and protein expressions in RL-14 cell line. The upregulation of CYP1B1 by 16-HETE enantiomers occurs via a transcriptional mechanism as evidenced by transcriptional induction and luciferase reporter assay. Furthermore, neither post-transcriptional nor post-translational modification was involved in such modulation since there was no change in CYP1B1 mRNA and protein stabilities upon treatment with 16-HETE enantiomers., Conclusion: The current study provides the first evidence that 16R-HETE and 16S-HETE increase CYP1B1 gene expression through a transcriptional mechanism., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Abstract: Cytochrome P450 1B1 (CYP1B1) is known to be involved in the pathogenesis of several cardiovascular diseases, including cardiac hypertrophy and heart failure, through the formation of cardiotoxic metabolites named as mid-chain hydroxyeicosatetraenoic acids (HETEs). Recently, we have demonstrated that fluconazole decreases the level of mid-chain HETEs in human liver microsomes, inhibits human recombinant CYP1B1 activity, and protects against angiotensin II-induced cellular hypertrophy in H9c2 cells. Therefore, the overall purpose of this study was to elucidate the potential cardioprotective effect of fluconazole against cardiac hypertrophy induced by abdominal aortic constriction (AAC) in rats. Male Sprague-Dawley rats were randomly assigned into 4 groups such as sham control rats, fluconazole-treated (20 mg/kg daily for 4 weeks, intraperitoneal) sham rats, AAC rats, and fluconazole-treated (20 mg/kg) AAC rats. Baseline and 5 weeks post-AAC echocardiography were performed. Gene and protein expressions were measured using real-time PCR and Western blot analysis, respectively. The level of mid-chain HETEs was determined using liquid chromatography-mass spectrometry. Echocardiography results showed that fluconazole significantly prevented AAC-induced left ventricular hypertrophy because it ameliorated the AAC-mediated increase in left ventricular mass and wall measurements. In addition, fluconazole significantly prevented the AAC-mediated increase of hypertrophic markers. The antihypertrophic effect of fluconazole was associated with a significant inhibition of CYP1B1, CYP2C23, and 12-LOX and a reduction in the formation rate of mid-chain HETEs. This study demonstrates that fluconazole protects against left ventricular hypertrophy, and it highlights the potential repurposing of fluconazole as a mid-chain HETEs forming enzymes' inhibitor for the protection against cardiac hypertrophy., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background and Objectives: Cytochrome P450 (CYP) 1A1 and CYP1B1 enzymes play a significant role in the pathogenesis of cancer and cardiovascular diseases (CVD) such as cardiac hypertrophy and heart failure. Previously, we have demonstrated that R- and S-enantiomers of 19-hydroxyeicosatetraenoic acid (19-HETE), an arachidonic acid endogenous metabolite, enantioselectively inhibit CYP1B1. The current study was conducted to test the possible inhibitory effect of novel synthetic analogues of R- and S-enantiomers of 19-HETE on the activity of CYP1A1, CYP1A2, and CYP1B1., Methods: The O-dealkylation rate of 7-ethoxyresorufin (EROD) by recombinant human CYP1A1 and CYP1B1, in addition to the O-dealkylation rate of 7-methoxyresorufin (MROD) by recombinant human CYP1A2, were measured in the absence and presence of varying concentrations (0-40 nM) of the synthetic analogues of 19(R)- and 19(S)-HETE. Also, the possible inhibitory effect of both analogues on the catalytic activity of EROD and MROD, using RL-14 cells and human liver microsomes, was assessed., Results: The results showed that both synthetic analogues of 19(R)- and 19(S)-HETE exhibited direct inhibitory effects on the activity of CYP1A1 and CYP1B1, while they had no significant effect on CYP1A2 activity. Nonlinear regression analysis and comparisons showed that the mode of inhibition for both analogues is noncompetitive inhibition of CYP1A1 and CYP1B1 enzymes. Also, nonlinear regression analysis and Dixon plots showed that the R- and S-analogues have K I values of 15.7 ± 4.4 and 6.1 ± 1.5 nM for CYP1A1 and 26.1 ± 2.9 and 9.1 ± 1.8 nM for CYP1B1, respectively. Moreover, both analogues were able to inhibit EROD and MROD activities in a cell-based assay and human liver microsomes., Conclusions: Therefore, the synthetic analogues of 19-HETE could be considered as a novel therapeutic approach in the treatment of cancer and CVD., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In March 2020, The World Health Organization (WHO) has declared that the coronavirus disease 2019 (COVID-19) is characterized as a global pandemic. As of September 2020, infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread to 213 countries and territories around the world, affected more than 31.5 million people, and caused more than 970,000 deaths worldwide. Although COVID-19 is a respiratory illness that mainly targets the lungs, it is currently well established that it is a multifactorial disease that affects other extra-pulmonary systems and strongly associated with a detrimental inflammatory response. Evidence has shown that SARS-CoV-2 causes perturbation in the arachidonic acid (AA) metabolic pathways; this disruption could lead to an imbalance between the pro-inflammatory metabolites of AA including mid-chain HETEs and terminal HETE (20-HETE) and the anti-inflammatory metabolites such as EETs and subterminal HETEs. Therefore, we propose novel therapeutic strategies to modulate the level of endogenous anti-inflammatory metabolites of AA and induce the patient's endogenous resolution mechanisms that will ameliorate the virus-associated systemic inflammation and enhance the primary outcomes in COVID-19 patients. Also, we propose that using nanoencapsulation of AA and its associated metabolites will contribute to the development of safer and more efficacious treatments for the management of COVID-19., Competing Interests: Conflict of interestThe authors declare that they have no conflicts of interest., (© Qatar University and Springer Nature Switzerland AG 2020.)

At the end of 2019, the entire world has witnessed the birth of a new member of coronavirus family in Wuhan, China. Ever since, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has swiftly invaded every corner on the planet. By the end of April 2020, almost 3.5 million cases have been reported worldwide, with a death toll of about 250,000 deaths. It is currently well-recognized that patient's immune response plays a pivotal role in the pathogenesis of Coronavirus Disease 2019 (COVID-19). This inflammatory element was evidenced by its elevated mediators that, in severe cases, reach their peak in a cytokine storm. Together with the reported markers of liver injury, such hyperinflammatory state may trigger significant derangements in hepatic cytochrome P450 metabolic machinery, and subsequent modulation of drug clearance that may result in unexpected therapeutic/toxic response. We hypothesize that COVID-19 patients are potentially vulnerable to a significant disease-drug interaction, and therefore, suitable dosing guidelines with therapeutic drug monitoring should be implemented to assure optimal clinical outcomes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Several reports demonstrated the direct contribution of cytochrome P450 1B1 (CYP1B1) enzyme and its associated cardiotoxic mid-chain, hydroxyeicosatetraenoic acid (HETEs) metabolites in the development of cardiac hypertrophy. Resveratrol is commercially available polyphenol that exerts beneficial effects in wide array of cardiovascular diseases including cardiac hypertrophy, myocardial infarction and heart failure. Nevertheless, the underlying mechanisms responsible for these effects are not fully elucidated. Since resveratrol is a well-known CYP1B1 inhibitor, the purpose of this study is to test whether resveratrol attenuates angiotensin II (Ang II)-induced cellular hypertrophy through inhibition of CYP1B1/mid-chain HETEs mechanism. RL-14 and H9c2 cells were treated with vehicle or 10 μM Ang II in the absence and presence of 2, 10 or 50 μM resveratrol for 24 h. Thereafter, the level of mid-chain HETEs was determined using liquid chromatography-mass spectrometry (LC/MS). Hypertrophic markers and CYP1B1 gene expression and protein levels were measured using real-time PCR and Western blot analysis, respectively. Our results demonstrated that resveratrol, at concentrations of 10 and 50 μM, was able to attenuate Ang-II-induced cellular hypertrophy as evidenced by substantial inhibition of hypertrophic markers, β-myosin heavy chain (MHC)/α-MHC and atrial natriuretic peptide. Ang II significantly induced the protein expression of CYP1B1 and increased the metabolite formation rate of its associated mid-chain HETEs. Interestingly, the protective effect of resveratrol was associated with a significant decrease of CYP1B1 protein expression and mid-chain HETEs. Our results provided the first evidence that resveratrol protects against Ang II-induced cellular hypertrophy, at least in part, through CYP1B1/mid-chain HETEs-dependent mechanism.

Cytochrome P450 1B1 (CYP1B1) has been reported to have a major role in metabolizing arachidonic acid (AA) into cardiotoxic metabolites, mid-chain hydroxyeicosatetraenoic acids (HETEs). Recently, we have shown that fluconazole decreases the level of mid-chain HETEs in human liver microsomes. Therefore, the objectives of this study were to investigate the effect of fluconazole on CYP1B1 mediated mid-chain HETEs and to explore its potential protective effect against angiotensin II- (Ang II)-induced cellular hypertrophy. To do this, Sprague Dawley rats were injected intraperitoneally with a single dose of fluconazole (20 mg/kg) for 24 h. Also, H9c2 and RL-14 cells were treated with 10 μM Ang II in the presence and absence of 50 μM fluconazole for 24 h. Our results demonstrated that treatment of rats with fluconazole significantly decreased the expression of CYP1B1 enzyme and the level of mid-chain HETEs in the heart. Furthermore, fluconazole was able to attenuate Ang-II-induced cellular hypertrophy as evidenced by a significant down-regulation of hypertrophic markers; β-myosin heavy chain (MHC)/α-MHC and brain natriuretic peptide (BNP) as well as cell surface area. In conclusion, our findings indicate that fluconazole protects against Ang II-induced cellular hypertrophy by repressing CYP1B1 and its associated mid-chain HETEs., (Copyright © 2020 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Hepatic inflammation is a key pathologic mediator in a wide array of acute and chronic liver diseases. Hepatitis is a crucial driver of liver tissue damage provoking the progression to severe fibrosis, cirrhosis and hepatocellular carcinoma, irrespective of the etiologic cause. Inflammatory liver diseases are collectively considered one of the most critical public health risks. Cytochrome P450 (CYP) enzymes are superfamily of monooxygenases which possess the greater diversity of substrate structures amidst all other enzyme families. Members of omega-3 as well as omega-6 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid and arachidonic acid, respectively, can be metabolized by CYP isoforms leading to the production of biologically active lipid mediators called eicosanoids. CYP-derived eicosanoids have been shown to play significant roles in the pathophysiology and protection of multiple inflammatory liver diseases. In this review, we elucidate the intricate role of CYP-derived eicosanoids in inflammation in liver diseases paving the way for better therapeutic approaches., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Cytochrome P450 (P450) enzymes are superfamily of monooxygenases that hold the utmost diversity of substrate structures and catalytic reaction forms amongst all other enzymes. P450 enzymes metabolize arachidonic acid (AA) to a wide array of biologically active lipid mediators. P450-mediated AA metabolites have a significant role in normal physiological and pathophysiological conditions, hence they could be promising therapeutic targets in different disease states. P450 monooxygenases mediate the (ω-n)-hydroxylation reactions, which involve the introduction of a hydroxyl group to the carbon skeleton of AA, forming subterminal hydroxyeicosatetraenoic acids (HETEs). In the current review, we specified different P450 isozymes implicated in the formation of subterminal HETEs in varied tissues. In addition, we focused on the role of subterminal HETEs namely 19-HETE, 16-HETE, 17-HETE and 18-HETE in different organs, importantly the kidneys, heart, liver and brain. Furthermore, we highlighted their role in hypertension, acute coronary syndrome, diabetic retinopathy, non-alcoholic fatty liver disease, ischemic stroke as well as inflammatory diseases. Since each member of subterminal HETEs exist as R and S enantiomer, we addressed the issue of stereoselectivity related to the formation and differential effects of these enantiomers. In conclusion, elucidation of different roles of subterminal HETEs in normal and disease states leads to identification of novel therapeutic targets and development of new therapeutic modalities in different disease states., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The overexpression of cytochrome P450 1B1 (CYP1B1) is a common characteristic of several diseases and conditions, such as inflammation, cancer, and cardiac hypertrophy. CYP1B1 is believed to contribute to pathogenesis of these diseases by mediating the formation of toxic compounds, either from exogenous or endogenous origin. We recently reported that an arachidonic acid metabolite, 19( S/R- )hydroxyeicosatetraenoic (HETE) acid, protects from cardiac hypertrophy by inhibiting the formation of toxic compounds, midchain HETEs, known to be formed by CYP1B1. This raised the question whether 19( S/R )-HETE can directly inhibit CYP1B1. In the current study, we report that 19( S/R )-HETE enantioselectively inhibits human recombinant CYP1B1 activity measured by 7-ethoxyresorufin O-deethylation assay. 19( S )-HETE is more potent than the R enantiomer ( K i = 37.3 and 89.1 nM, respectively). Noncompetitive inhibition was identified as the mechanism of CYP1B1 inhibition, which underlines the potentially important physiologic role of 19( S/R )-HETE as an endogenous CYP1B1 inhibitor; to our knowledge, 19( S/R )-HETE is the first inhibitor of its kind to be reported., (Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics.)

Numerous epidemiological studies have demonstrated that approximately 40% of myocardial infarctions (MI) are associated with heart failure (HF). Resveratrol, a naturally occurring polyphenol, has been shown to be beneficial in the treatment of MI-induced HF in rodent models. However, the mechanism responsible for the effects of resveratrol are poorly understood. Interestingly, resveratrol is known to inhibit cytochrome P450 1B1 (CYP1B1) which is involved in the formation of cardiotoxic hydroxyeicosatetraenoic acid (HETE) metabolites. Therefore, we investigated whether resveratrol could improve MI-induced cardiac remodeling and HF in rats through the inhibition of CYP1B1 and its metabolites. To do this, rats were subjected to either sham surgery or a surgery to ligate the left anterior descending artery to induce a MI and subsequent HF. Three weeks post-surgery, rats with established HF were treated with control diet or administered a diet containing low dose of resveratrol. Our results showed that low dose resveratrol treatment significantly improves % ejection fraction in MI rats and reduces MI-induced left ventricular and atrial remodeling. Furthermore, non-cardiac symptoms of HF such as reduced physical activity improved with low dose resveratrol treatment. Mechanistically, low dose resveratrol treatment of rats with established HF restored levels of fatty acid oxidation and significantly improved cardiac energy metabolism as well as significantly inhibited CYP1B1 and cardiotoxic HETE metabolites induced in MI rats. Overall, the present work provides evidence that low dose resveratrol reduces the severity of MI-induced HF, at least in part, through the inhibition of CYP1B1 and cardiotoxic HETE metabolites., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We had recently demonstrated that the racemic mixture of 19-hydroxyeicosatetraenoic acid (19-HETE) protects against angiotensin II (Ang II)-induced cardiac hypertrophy. Therefore, the purpose of this study was to investigate whether the R- or S- enantiomer of 19-HETE confers cardioprotection against Ang II-induced cellular hypertrophy in RL-14 and H9c2 cells. Both cell lines were treated with vehicle or 10 μ M Ang II in the absence and presence of 20 μ M 19( R ) - HETE or 19( S ) - HETE for 24 hours. Thereafter, the level of midchain HETEs was determined using liquid chromatography-mass spectrometry. Gene- and protein-expression levels were measured using real-time polymerase chain reaction and Western blot analysis, respectively. The results showed that both 19( R ) - HETE and 19( S ) - HETE significantly decreased the metabolite formation rate of midchain HETEs, namely 8-, 9-, 12-, and 15-HETE, compared with control group, whereas the level of 5-HETE was selectively decreased by S- enantiomer. Moreover, both 19( R ) - HETE and 19( S ) - HETE significantly inhibited the catalytic activity of CYP1B1 and decreased the protein expression of 5- and 12-lipoxygenase (LOX) as well as cyclo-oxygenase-2 (COX-2). Notably, the decrease in 15-LOX protein expression was only mediated by 19( S ) - HETE. Interestingly, both enantiomers protected against Ang II-induced cellular hypertrophy, as evidenced by a significant decrease in mRNA expression of β / α -myosin heavy chain ratio, atrial natriuretic peptide, and interleukins 6 and 8. Our data demonstrated that S- enantiomer of 19-HETE preferentially protected against Ang II-induced cellular hypertrophy by decreasing the level of midchain HETEs, inhibiting catalytic activity of CYP1B1, decreasing protein expression of LOX and COX-2 enzymes, and decreasing mRNA expression of IL-6 and IL-8., (Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.)

Benign prostate hyperplasia (BPH) is a common age-related health problem affecting almost 3 out of 4 men in their sixties. Chrysin is a dietary phytoestrogen found naturally in bee propolis and various plant extracts. It possesses antioxidant, anti-inflammatory and anti-proliferative properties. The current study was conducted to explore the role chrysin plays in protection against testosterone-induced BPH in rats. On grounds of a preliminary experiment, a dose of chrysin (50 mg/kg) was chosen for further investigation. Testosterone significantly depleted glutathione, suppressed superoxide dismutase and catalase activities, and elevated lipid peroxidation. Moreover, it markedly scaled down the level of cleaved caspase-3 enzyme, reduced Bax/Bcl-2 ratio and mRNA expression of p53 and p21; conversely, protein expression of proliferating cell nuclear antigen was enhanced. Chrysin alleviated testosterone-induced oxidative stress and restored cleaved caspase-3 level, Bax/Bcl-2 ratio and mRNA expression of p53 and p21 to almost control levels. Chrysin prevented the increase in binding activity of nuclear factor kappa B (NF-κB) p65 subunit, mRNA expression of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 1 receptor (IGF-1R). These data highlight the protective role of chrysin against experimentally-induced BPH. This is attributed - at least partly - to its antioxidant, antiproliferative and proapoptotic properties., (Copyright © 2017. Published by Elsevier Ltd.)

Recent data demonstrated the role of CYP1B1 in cardiovascular disease. It was, therefore, necessary to examine whether the inhibition of CYP1B1 and hence inhibiting the formation of its metabolites, using 2,4,3',5'-tetramethoxystilbene (TMS), would have a cardioprotective effect against angiotensin II (Ang II)-induced cardiac hypertrophy. For this purpose, male Sprague Dawley rats were treated with Ang II with or without TMS (300 μg/kg every third day i.p.). Thereafter, cardiac hypertrophy and the formation of mid-chain HETEs and arachidonic acid were assessed. In vitro, RL-14 cells were treated with Ang II (10 μM) in the presence and absence of TMS (0.5 μM). Then, reactive oxygen species, mitogen-activated protein kinase phosphorylation levels, and nuclear factor-kappa B-binding activity were determined. Our results demonstrated that TMS protects against Ang II-induced cardiac hypertrophy as indicated by the improvement in cardiac functions shown by the echocardiography as well as by reversing the increase in heart weight to tibial length ratio caused by Ang II. In addition, the cardioprotective effect of TMS was associated with a significant decrease in cardiac mid-chain HETEs levels. Mechanistically, TMS inhibited reactive oxygen species formation, the phosphorylation of ERK1/2, p38 mitogen-activated protein kinase, and the binding of p65 NF-κB.

Cytochrome P450-mediated metabolism of arachidonic acid (AA) is an important pathway for the formation of eicosanoids. The ω-hydroxylation of AA generates significant levels of 20-hydroxyeicosatetraenoic acid (20-HETE) in various tissues. In the current review, we discussed the role of 20-HETE in the kidney, liver, lung, and brain during physiological and pathophysiological states. Moreover, we discussed the role of 20-HETE in tumor formation, metabolic syndrome and diabetes. In the kidney, 20-HETE is involved in modulation of preglomerular vascular tone and tubular ion transport. Furthermore, 20-HETE is involved in renal ischemia/reperfusion (I/R) injury and polycystic kidney diseases. The role of 20-HETE in the liver is not clearly understood although it represents 50%-75% of liver CYP-dependent AA metabolism, and it is associated with liver cirrhotic ascites. In the respiratory system, 20-HETE plays a role in pulmonary cell survival, pulmonary vascular tone and tone of the airways. As for the brain, 20-HETE is involved in cerebral I/R injury. Moreover, 20-HETE has angiogenic and mitogenic properties and thus helps in tumor promotion. Several inhibitors and inducers of the synthesis of 20-HETE as well as 20-HETE analogues and antagonists are recently available and could be promising therapeutic options for the treatment of many disease states in the future.

Benign prostatic hyperplasia (BPH) is uncontrolled proliferation of prostate tissue. Metformin, a widely prescribed anti-diabetic agent, possesses anticancer activity through induction of apoptotic signaling and cell cycle arrest. This study aimed to investigate the protective effect of metformin against experimentally-induced BPH in rats. Treatment with 500 and 1000 mg/kg metformin orally for 14 days significantly inhibited testosterone-mediated increase in the prostate weight &prostate index (prostate weight/body weight [mg/g]) and attenuated the pathological alterations induced by testosterone. Mechanistically, metformin significantly protected against testosterone-induced elevation of estrogen receptor-α (ER-α) and decrease of estrogen receptor-β (ER-β) expression, with no significant effect of androgen receptor (AR) and 5α-reductase expression. It decreased mRNA expression of IGF-1 and IGF-1R and protein expression ratio of pAkt/total Akt induced by testosterone. Furthermore, it significantly ameliorated testosterone-induced reduction of mRNA expression Bax/Bcl-2 ratio, P21 and phosphatase and tensin homolog (PTEN) and AMPK [PT-172] activity. In conclusion, these findings elucidate the effectiveness of metformin in preventing testosterone-induced BPH in rats. These results could be attributed, at least partly, to its ability to enhance expression ratio of ER-β/ER-α, decrease IGF-1, IGF-1R and pAkt expressions, increase P21, PTEN, Bax/Bcl-2 expressions and activate AMPK with a subsequent inhibition of prostate proliferation.