Low endogenous bioavailable testosterone levels have been shown to be associated with higher rates
of all‐cause and cardiovascular‐related mortality.39,41,46–47 Patients suffering from CAD,13–18 CHF,137 T2DM,25–26 and obesity27–28
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Secondary causes of hyperlipidemia. [Med Clin North Am. 1994] - PubMed - NCBI - 0 views
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Testosterone and the Cardiovascular System: A Comprehensive Review of the Clinical Lite... - 0 views
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have all been shown to have lower levels of endogenous testosterone compared with those in healthy controls. In addition, the severity of CAD15,17,29–30 and CHF137 correlates with the degree of testosterone deficiency
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In patients with CHF, testosterone replacement therapy has been shown to significantly improve exercise tolerance while having no effect on LVEF
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testosterone therapy causes a shift in the skeletal muscle of CHF patients toward a higher concentration of type I muscle fibers
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Testosterone replacement therapy has also been shown to improve the homeostatic model of insulin resistance and hemoglobin A1c in diabetics26,68–69 and to lower the BMI in obese patients.
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Lower levels of endogenous testosterone have been associated with longer duration of the QTc interval
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negative correlation has been demonstrated between endogenous testosterone levels and IMT of the carotid arteries, abdominal aorta, and thoracic aorta
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These findings suggest that men with lower levels of endogenous testosterone may be at a higher risk of developing atherosclerosis.
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Current guidelines from the Endocrine Society make no recommendations on whether patients with heart disease should be screened for hypogonadism and do not recommend supplementing patients with heart disease to improve survival.
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The Massachusetts Male Aging Study also projects ≈481 000 new cases of hypogonadism annually in US men within the same age group
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since 1993 prescriptions for testosterone, regardless of the formulation, have increased nearly 500%
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Testosterone levels are lower in patients with chronic illnesses such as end‐stage renal disease, human immunodeficiency virus, chronic obstructive pulmonary disease, type 2 diabetes mellitus (T2DM), obesity, and several genetic conditions such as Klinefelter syndrome
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A growing body of evidence suggests that men with lower levels of endogenous testosterone are more prone to develop CAD during their lifetimes
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There are 2 major potential confounding factors that the older studies generally failed to account for. These factors are the subfraction of testosterone used to perform the analysis and the method used to account for subclinical CAD.
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The biologically inactive form of testosterone is tightly bound to SHBG and is therefore unable to bind to androgen receptors
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The biologically inactive fraction of testosterone comprises nearly 68% of the total testosterone in human serum
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The biologically active subfraction of testosterone, also referred to as bioavailable testosterone, is either loosely bound to albumin or circulates freely in the blood, the latter referred to as free testosterone
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It is estimated that ≈30% of total serum testosterone is bound to albumin, whereas the remaining 1% to 3% circulates as free testosterone
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it can be argued that using the biologically active form of testosterone to evaluate the association with CAD will produce the most reliable results
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English et al14 found statistically significant lower levels of bioavailable testosterone, free testosterone, and free androgen index in patients with catheterization‐proven CAD compared with controls with normal coronary arteries
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patients with catheterization‐proven CAD had statistically significant lower levels of bioavailable testosterone
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In conclusion, existing evidence suggests that men with CAD have lower levels of endogenous testosterone,13–18 and more specifically lower levels of bioavailable testosterone
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In a meta‐analysis of these 7 population‐based studies, Araujo et al41 showed a trend toward increased cardiovascular mortality associated with lower levels of total testosterone, but statistical significance was not achieved (RR, 1.25
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the authors showed that a decrease of 2.1 standard deviations in levels of total testosterone was associated with a 25% increase in the risk of cardiovascular mortality
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the relative risk of all‐cause mortality in men with lower levels of total testosterone was calculated to be 1.35
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higher risk of cardiovascular mortality is associated with lower levels of bioavailable testosterone
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Existing evidence seems to suggest that lower levels of endogenous testosterone are associated with higher rates of all‐cause mortality and cardiovascular mortality
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studies have shown that lower levels of endogenous bioavailable testosterone are associated with higher rates of all‐cause and cardiovascular mortality
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It may be possible that using bioavailable testosterone to perform mortality analysis will yield more accurate results because it prevents the biologically inactive subfraction of testosterone from playing a potential confounding role in the analysis
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In more recent studies, 3 randomized, placebo‐controlled trials demonstrated that administration of testosterone improves myocardial ischemia in men with CAD
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The improvement in myocardial ischemia was shown to occur in response to both acute and chronic testosterone therapy and seemed to be independent of whether an intravenous or transdermal formulation of testosterone was used.
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There is growing evidence from in vivo animal models and in vitro models that testosterone induces coronary vasodilation by modulating the activity of ion channels, such as potassium and calcium channels, on the surface of vascular smooth muscle cells
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Experimental studies suggest that the most likely mechanism of action for testosterone on vascular smooth muscle cells is via modulation of action of non‐ATP‐sensitive potassium ion channels, calcium‐activated potassium ion channels, voltage‐sensitive potassium ion channels, and finally L‐type calcium ion channels
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Corona et al confirmed those results by demonstrating that not only total testosterone levels are lower among diabetics, but also the levels of free testosterone and SHBG are lower in diabetic patients
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Laaksonen et al65 followed 702 Finnish men for 11 years and demonstrated that men in the lowest quartile of total testosterone, free testosterone, and SHBG were more likely to develop T2DM and metabolic syndrome.
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Vikan et al followed 1454 Swedish men for 11 years and discovered that men in the highest quartile of total testosterone were significantly less likely to develop T2DM
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authors demonstrated a statistically significant increase in the incidence of T2DM in subjects receiving gonadotropin‐releasing hormone antagonist therapy. In addition, a significant increase in the rate of myocardial infarction, stroke, sudden cardiac death, and development of cardiovascular disease was noted in patients receiving antiandrogen therapy.67
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Several authors have demonstrated that the administration of testosterone in diabetic men improves the homeostatic model of insulin resistance, hemoglobin A1c, and fasting plasma glucose
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Existing evidence strongly suggests that the levels of total and free testosterone are lower among diabetic patients compared with those in nondiabetics
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insulin seems to be acting as a stimulant for the hypothalamus to secret gonadotropin‐releasing hormone, which consequently results in increased testosterone production. It can be argued that decreased stimulation of the hypothalamus in diabetics secondary to insulin deficiency could result in hypogonadotropic hypogonadism
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This interaction may be a result of the promotion of lipolysis in abdominal adipose tissue by testosterone, which may in turn cause reduced abdominal adiposity. On the other hand, given that adipose tissue has a higher concentration of the enzyme aromatase, it could be that increased adipose tissue results in more testosterone being converted to estrogen, thereby causing hypogonadism. Third, increased abdominal obesity may cause reduced testosterone secretion by negatively affecting the hypothalamus‐pituitary‐testicular axis. Finally, testosterone may be the key factor in activating the enzyme 11‐hydroxysteroid dehydrogenase in adipose tissue, which transforms glucocorticoids into their inactive form.
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increasing age may alter the association between testosterone and CRP. Another possible explanation for the association between testosterone level and CRP is central obesity and waist circumference
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Bai et al have provided convincing evidence that testosterone might be able to shorten the QTc interval by augmenting the activity of slowly activating delayed rectifier potassium channels while simultaneously slowing the activity of L‐type calcium channels
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Intima‐media thickness (IMT) of the carotid artery is considered a marker for preclinical atherosclerosis
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Studies have shown that levels of endogenous testosterone are inversely associated with IMT of the carotid artery,126–128,32,129–130 as well as both the thoracic134 and the abdominal aorta
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1 study has demonstrated that lower levels of free testosterone are associated with accelerated progression of carotid artery IMT
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another study has reported that decreased levels of total and bioavailable testosterone are associated with progression of atherosclerosis in the abdominal aorta
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These findings suggest that normal physiologic testosterone levels may help to protect men from the development of atherosclerosis
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Czesla et al successfully demonstrated that the muscle specimens that were exposed to metenolone had a significant shift in their composition toward type I muscle fibers
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Type I muscle fibers, also known as slow‐twitch or oxidative fibers, are associated with enhanced strength and physical capability
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It has been shown that those with advanced CHF have a higher percentage of type II muscle fibers, based on muscle biopsy
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Studies have shown that men with CHF suffer from reduced levels of total and free testosterone.137 It has also been shown that reduced testosterone levels in men with CHF portends a poor prognosis and is associated with increased CHF mortality.138 Reduced testosterone has also been shown to correlate negatively with exercise capacity in CHF patients.
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Testosterone replacement therapy has been shown to significantly improve exercise capacity, without affecting LVEF
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the results of the 3 meta‐analyses seem to indicate that testosterone replacement therapy does not cause an increase in the rate of adverse cardiovascular events
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Data from 3 meta‐analyses seem to contradict the commonly held belief that testosterone administration may increase the risk of developing prostate cancer
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One meta‐analysis reported an increase in all prostate‐related adverse events with testosterone administration.146 However, when each prostate‐related event, including prostate cancer and a rise in PSA, was analyzed separately, no differences were observed between the testosterone group and the placebo group
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the existing data from the 3 meta‐analyses seem to indicate that testosterone replacement therapy does not increase the risk of adverse cardiovascular events
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the authors correctly point out the weaknesses of their study which include retrospective study design and lack of randomization, small sample size at extremes of follow‐up, lack of outcome validation by chart review and poor generalizability of the results given that only male veterans with CAD were included in this study
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the studies that failed to find an association between testosterone and CRP used an older population group
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low testosterone may influence the severity of CAD by adversely affecting the mediators of the inflammatory response such as high‐sensitivity C‐reactive protein, interleukin‐6, and tumor necrosis factor–α
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Good review of Testosterone and CHD. Low T is associated with increased all cause mortality and cardiovascular mortality, CAD, CHF, type II diabetes, obesity, increased IMT, increased severity of CAD and CHF. Testosterone replacement in men with low T has been shown to improve exercise tolerance in CHF, improve insulin resistance, improve HgbA1c and lower BMI in the obese.
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Testosterone Deficiency, Cardiac Health, and Older Men - 0 views
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Studies have shown pharmacological doses of testosterone to relax coronary arteries when injected intraluminally [39] and to produce modest but consistent improvement in exercise-induced angina and reverse associated ECG changes [40]. The mechanism of action is via blockade of calcium channels with effect of similar magnitude to nifedipine
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men with chronic stable angina pectoris, the ischaemic threshold increased after 4 weeks of TRT and a recent study demonstrates improvement continuing beyond 12 months [
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Studies have shown an inverse relationship between serum testosterone and fasting blood glucose and insulin levels
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Medications such as chronic analgesics, anticonvulsants, 5ARIs, and androgen ablation therapy are associated with increased risk of testosterone deficiency and insulin resistance
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Women with T2D or metabolic syndrome characteristically have low SHBG and high free testosterone
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The precise interaction between insulin resistance, visceral adiposity, and hypogonadism is, as yet, unclear but the important mechanisms are through increased aromatase production, raised leptin levels, and increase in inflammatory kinins
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Men should be encouraged to combine aerobic exercise with strength training. As muscle increases, glucose will be burned more efficiently and insulin levels will fall. A minimum of 30 minutes exercise three times weekly should be advised
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studies now clearly show that low testosterone leads to visceral obesity and metabolic syndrome and is also a consequence of obesity
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In the case of MMAS [43], a baseline total testosterone of less than 10.4 nmol/L was associated with a greater than 4-fold incidence of type 2 diabetes over the next 9 years
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Low testosterone predicts increased mortality and testosterone therapy improves survival in 587 men with type 2 diabetes
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A similar retrospective US study involved 1031 men with 372 on TRT. The cumulative mortality was 21% in the untreated group versus 10% ( ) in the treated group with the greatest effect in younger men and those with type 2 diabetes
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the presence of ED has been shown to be an independent risk factor, particularly in hypogonadal men, increasing the risk of cardiac events by over 50%
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A recent online publication on ischaemic heart disease mortality in men concluded optimal androgen levels are a biomarker for survival
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A recent 10 year study from Western Australia involving 3690 men followed up from 2001–2010 concluded that TT and FT levels in the normal range were associated with decreased all-cause and cardiovascular mortality, for the first time suggesting that both low and DHT are associated with all-cause mortality and higher levels of DHT reduced cardiovascular risk
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The effect of treatment with TRT reduced the mortality rate of treated cohort (8.4%) to that of the eugonadal group whereas the mortality for the untreated remained high at 19.2%
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Men with angiographically proven CAD (coronary artery disease) have significantly lower testosterone levels [29] compared to controls ( ) and there was a significant inverse relationship between the degree of CAD and TT (total testosterone) levels
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men treated with long acting testosterone showed highly significant reductions in TC, LDL, and triglycerides with increase in HDL, associated with significant reduction in weight, BMI, and visceral fat
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In some studies, a decline in diastolic blood pressure has been observed, after 3–9 months [24, 26] and in systolic blood pressure
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TRT has been shown to upregulate PDE5 [65] and enhance the effect of PDE5Is (now an accepted therapy for both ED and LUTS), it no longer seems logical to advice avoidance of TRT in men with mild to moderate BPH.
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Several meta-analyses have failed to show a link between TRT and development of prostate cancer [66] but some studies have shown a tendency for more aggressive prostate cancer in men with low testosterone
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low bioavailable testosterone and high SHBG were associated with a 4.9- and 3.2-fold risk of positive biopsy
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Current EAU, ISSAM, and BSSM guidance [1, 2] is that there is “no evidence TRT is associated with increased risk of prostate cancer or activation of subclinical cancer.”
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Men with prostate cancer, treated with androgen deprivation, develop an increase of fat mass with an altered lipid profile
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Erectile dysfunction is an established marker for future cardiovascular risk and the major presenting symptom leading to a diagnosis of low testosterone
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Diet-induced obesity and low testosterone increase neuroinflammation and impair neural ... - 0 views
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both obesity and low testosterone are also risk factors for neural dysfunction, including cognitive impairment [58–61] and development of AD
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diet-induced obesity causes significant metabolic disturbances and impairs central and peripheral nervous systems.
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both obesity and low testosterone are linked with promotion of inflammatory pathways [70–72] and exert harmful actions on the central [73–75] and peripheral [29,76] nervous systems
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In general, obesity-related changes were worsened by low testosterone and improved by testosterone treatment; however, this relationship was not statistically significant in several instances. Further, our data suggest that a common pathway that may contribute to obesity and testosterone effects is regulation of inflammation
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fasting blood glucose levels were independently and additively increased by GDX-induced testosterone depletion and high-fat diet
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testosterone treatment significantly reduced fasting glucose under both the normal and high-fat diets, demonstrating potential therapeutic efficacy of testosterone supplementation
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fasting insulin, insulin resistance (HOMA index), and glucose tolerance, low testosterone tended to exacerbate and or testosterone treatment improved outcomes.
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testosterone’s effects likely do not indicate an indirect result on adiposity but rather regulatory action(s) on other aspects of metabolic homeostasis
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Prior work in rodents has shown diet-induced obesity induces insulin resistance in rat brain [63] and that testosterone replacement improves insulin sensitivity in obese rats [64]. Our findings are consistent with the human literature, which indicates that (i) testosterone levels are inversely correlated to insulin resistance and T2D in healthy [30,65] as well as obese men [66], and (ii) androgen therapy can improve some metabolic measures in overweight men with low testosterone
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it has been shown that TNFα has inhibitory effects on neuron survival, differentiation, and neurite outgrowth
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Our data demonstrate that low testosterone and obesity independently increased cerebrocortical mRNA levels of both TNFα and IL-1β
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many beneficial effects of testosterone, including inhibition of proinflammatory cytokine expression
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neuroprotection [80,81], are dependent upon androgen receptors, the observed effects of testosterone in this study may involve androgen receptor activation
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testosterone can be converted by the enzyme aromatase into estradiol, which is also known to exert anti-inflammatory [82] and neuroprotective [83] actions
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Since testosterone can affect glial function [86] and improve neuronal growth and survival [87–89], it was unexpected that testosterone status exhibited rather modest effects on neural health indices with the only significant response being an increase in survival in the testosterone-treated, high-fat diet group
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testosterone treatment significantly lowered TNFα and IL-1β expression to near basal levels even in obese mice, indicating a protective benefit of testosterone across diet conditions
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Testosterone status and diet-induced obesity were associated with significant regulation of macrophage infiltration
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a possible mechanism by which obesity and testosterone levels may affect the health of both CNS and PNS
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Study points to obesity and low Testosterone contribution of neuroinflammation. No effect of body weight was seen with TRT. This animal model found similar positive effects of TRT in insulin sensitivity. Obesity and low T increase inflammatory cytokine production: this study found an increase in TNF-alpha and IL-1beta and TRT reduced TNF-alpha and IL-1beta to near base-line. Testosterone is neuroprotective and this study reviewed the small volume of evaded that pointed to benefit from estradiol. Testosterone's effect on glial survival was positive but not significant. Obesity and low T were found to be associated with increased macrophage infiltration in the PNS with increased TNF-alpha and IL-1beta. Testosterone therapy improved peripheral neuropathy via its positive effects on nocicieption.
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EHP - Bisphenol A Exposure during Adulthood Causes Augmentation of Follicular... - 0 views
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Bisphenol A shown to disrupt ovarian estrogen production from exposure in adults. The point of this that is important is that BPA, a xenoestrogen, can infact disrupt physiologic hormone production in adults, and contribute to ovarian failure. BPA, itself, is 1,000 fold weaker than E2, yet it disrupts ovarian function.
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A PERSPECTIVE ON THE ROLE OF ESTROGEN IN HORMONE-INDUCED PROSTATE CARCINOGENESIS - 0 views
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Pituitary Function in a Man with Congenital Aromatase Deficiency: Effect of Different D... - 0 views
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the congenital lack of estrogen activity seems to be associated with a slightly impaired secretion of PRL and TSH
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Cellular and Molecular Basis of Deiodinase-Regulated Thyroid Hormone Signaling: Endocri... - 0 views
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From a broad perspective, this paradigm can be seen as an example of how hormones are activated or inactivated in a controlled fashion in specific extraglandular tissues, in an analogous role to 5α-reductase and P450 aromatase in sex steroid metabolism and to 11β-hydroxysteroid dehydrogenase in glucocorticoid metabolism.
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An Overview of Melatonin and Breast Cancer | Natural Medicine Journal - 0 views
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Overall its effect on cancer cells is oncostatic at physiological levels, or cytotoxic at higher concentrations
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direct antioxidant, antimitotic, antiestrogenic, prodifferentiating and antimetastatic effects have been well characterized
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On a cellular level, melatonin acts as a selective estrogen receptor modulator (SERM) through decreased expression of estrogen receptor alpha and reduction in the ability of estrogen-estrogen receptor alpha (ERα) complex to bind to the estrogen response element (ERE) on DNA
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Melatonin also acts as a selective estrogen enzyme modulator (SEEM), reducing the activity of aromatase in cells
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Subcutaneous testosterone-letrozole therapy before and concu... : Menopause - 0 views
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Reduced breast cancer incidence in women treated with subcutaneous testosterone, or tes... - 0 views
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