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Arnold S.L.,University of Washington | Kent T.,Washington State University | Hogarth C.A.,Washington State University | Schlatt S.,Center for Reproductive Medicine and Andrology | And 7 more authors.
Journal of Lipid Research | Year: 2015

Retinoic acid (RA), the active metabolite of vitamin A, is required for spermatogenesis and many other biological processes. RA formation requires irreversible oxidation of retinal to RA by aldehyde dehydrogenase enzymes of the 1A family (ALDH1A). While ALDH1A1, ALDH1A2, and ALDH1A3 all form RA, the expression pattern and relative contribution of these enzymes to RA formation in the testis is unknown. In this study, novel methods tomeasure ALDH1A protein levels and intrinsic RA formation were used to accurately predict RA formation velocities in individual human testis samples and an association between RA formation and intratesticular RA concentrations was observed. The distinct localization of ALDH1A in the testis suggests a specifi c role for each enzyme in controlling RA formation. ALDH1A1 was found in Sertoli cells,while only ALDH1A2 was found in spermatogonia, spermatids, and spermatocytes. in theabsence of cellular retinol binding protein (CRBP)1, ALDH1A1 was predicted to be the main contributor to intratesticular RA formation, but when CRBP1 was present, ALDH1A2 was predicted to be equally important in RA formation as ALDH1A1. This study provides a comprehensive novel methodology to evaluate RA homeostasis in human tissues and provides insight to how the individual ALDH1A enzymes mediate RA concentrations in specifi c cell types. - Arnold, S. L., T. Kent, C. A. Hogarth, S. Schlatt, B. Prasad, M. Haenisch, T. Walsh, C. H. Muller, M. D. Griswold, J. K. Amory,and N. Isoherranen. Importance of ALDH1A enzymes in determining human testicular retinoic acid concentrations. J. Lipid Res. 2015. 56:342-357. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc. Source

Traish A.M.,Boston University | Guay A.T.,Tufts University | Zitzmann M.,Center for Reproductive Medicine and Andrology
Hormone Molecular Biology and Clinical Investigation | Year: 2014

5α-reductases, a unique family of enzymes with a wide host of substrates and tissue distributions, play a key role in the metabolism of androgens, progestins, mineralocorticoids and glucocorticoids. These enzymes are the rate-limiting step in the synthesis of a host of neurosteroids, which are critical for central nervous system function. Androgens and glucocorticoids modulate mitochondrial function, carbohydrate, protein and lipid metabolism and energy balance. Thus, the inhibition of these regulatory enzymes results in an imbalance in steroid metabolism and clearance rates, which leads to altered physiological processes. In this report, we advance the hypothesis that inhibition of 5α-reductases by finasteride and dutasteride alters not only steroid metabolism but also interferes with the downstream actions and signaling of these hormones. We suggest that finasteride and dutasteride inhibit 5α-reductase activities and reduce the clearance of glucocorticoids and mineralocorticoids, potentiating insulin resistance, diabetes and vascular disease. © 2014 by De Gruyter 2014. Source

Traish A.M.,Boston University | Zitzmann M.,Center for Reproductive Medicine and Andrology
Reviews in Endocrine and Metabolic Disorders | Year: 2015

Testosterone deficiency (TD) is a well-established and recognized medical condition that contributes to several co-morbidities, including metabolic syndrome, visceral obesity and cardiovascular disease (CVD). More importantly, obesity is thought to contribute to TD. This complex bidirectional interplay between TD and obesity promotes a vicious cycle, which further contributes to the adverse effects of TD and obesity and may increase the risk of CVD. Testosterone (T) therapy for men with TD has been shown to be safe and effective in ameliorating the components of the metabolic syndrome (Met S) and in contributiong to increased lean body mass and reduced fat mass and therefore contributes to weight loss. We believe that appropriate T therapy in obese men with TD is a novel medical approach to manage obesity in men with TD. Indeed, other measures of lifestyle and behavioral changes can be used to augment but not fully replace this effective therapeutic approach. It should be noted that concerns regarding the safety of T therapy remain widely unsubstantiated and considerable evidence exists supporting the benefits of T therapy. Thus, it is paramount that clinicians managing obese men with TD be made aware of this novel approach to treatment of obesity. In this review, we discuss the relationship between TD and obesity and highlight the contemporary advancement in management of obesity with pharmacological and surgical approaches, as well as utilization of T therapy and how this intervention may evolve as a novel approach to treatment of obesity in men with TD. © 2015, Springer Science+Business Media New York. Source

Muller T.,Stem Cell Biology Unit | Muller T.,Hannover Medical School | Hupfeld T.,Stem Cell Biology Unit | Roessler J.,Hannover Medical School | And 3 more authors.
Journal of Medical Primatology | Year: 2011

Background Common marmoset monkeys (Callithrix jacchus) are readily used in biomedical research. However, superovulation for embryonic stem cell production and developmental research still remain difficult. Inexplicably, follicle-stimulating hormone (FSH) as key player in superovulation has to be administered in extremely high dosages in this non-human primate compared to human. Methods To evaluate whether marmoset FSH (cjFSH) is functionally more competent than its human homologue on the marmoset FSH receptor (cjFSHR), we established in vitro a homologous system characterizing homologous and recombinantly produced cjFSH. Results Upon stimulation of two cell lines stably expressing either the marmoset or the human FSH receptor (cj/hFSHR), respectively, the second messenger signaling of the activated receptor displayed no significant difference in ED50 values. Thermostability of cjFSH was significantly prolonged by roughly 20% on both FSHRs. Conclusion High FSH dosage in marmoset superovulation cannot be explained by enhanced biopotency of the natural animal's gonadotropin. © 2010 John Wiley & Sons A/S. Source

Wu F.,University of Manchester | Zitzmann M.,Center for Reproductive Medicine and Andrology | Heiselman D.,Eli Lilly and Company | Donatucci C.,Eli Lilly and Company | And 3 more authors.
Journal of Sexual Medicine | Year: 2016

Introduction: Evidence from well-designed studies documenting the benefit of testosterone replacement therapy as a function of patient demographic and clinical characteristics is lacking. Aim: To determine demographic and clinical predictors of treatment outcomes in hypogonadal men with low sex drive, low energy, and/or erectile dysfunction. Methods: Post hoc analysis of a randomized, multicenter, double-blinded, placebo-controlled, 16-week study of 715 hypogonadal men (mean age = 55.3 years, age range = 19-92 years) presenting with low sex drive and/or low energy who received placebo or testosterone solution 2% for 12 weeks. Main Outcomes and Measures: Two levels defined patient-reported improvement (PRI) in sex drive or energy: level 1 was at least "a little better" and level 2 was at least "much better" in energy or sex drive on the Patient Global Impression of Improvement at study end point. PRI in erectile function was stratified by erectile dysfunction severity at baseline as measured by the erectile function domain of the International Index for Erectile Function: mild at baseline (change of 2), moderate at baseline (change of 5), and severe at baseline (change of 7). Associations of demographic and clinical characteristics with PRI were calculated with stepwise forward multiple logistic regression analysis. Odds ratios represented the likelihood of PRI in symptoms among variable categories. Results: Higher levels of end-point testosterone were associated with higher rates of PRI (at levels 1 and 2) in sex drive and energy (P < .001 for the two comparisons). Lower baseline testosterone levels were associated with higher rates of level 1 PRI in sex drive (P = .028); and classic hypogonadism (vs non-classic hypogonadism) was associated with higher rates of level 2 PRI in sex drive (P = .005) and energy (P = .006). Conclusion: When assessing the potential for improvements in men with testosterone deficiency using patient-reported outcome questionnaires, possible predictors of treatment outcomes to consider include the etiology of hypogonadism and testosterone levels (baseline and end point). © 2016. Source

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