Skip to main content

Home/ Dr. Goodyear/ Group items tagged leptin

Rss Feed Group items tagged

Filter: All | Bookmarks | Topics Simple Middle
Nathan Goodyear

Leptin and Androgens in Male Obesity: Evidence for Leptin Contribution to Reduced Andro... - 0 views

press.endocrine.org/...jcem.84.10.6082

obesity leptin low T low Testosterone Testosterone low T leydig cells LH leutenizing hormone men male hormones hormone

shared by Nathan Goodyear on 04 Sep 14 - No Cached
  • in male obesity basal and LH-stimulated androgen levels are reduced and inversely correlated with circulating leptin
  • functional leptin receptors are present in rodent Leydig cells
  • it is conceivable that in males high leptin concentrations may have a direct inhibitory effect(s) on Leydig cell function.
  • ...18 more annotations...
  • insulin is an important inhibitor of the synthesis of SHBG
  • no correlation between leptin and SHBG levels
  • SHBG reduction in obesity is a minor determinant of lowered androgen levels
  • SHBG can explain only up to 3% of the correlation
  • testicular T de novo production is impaired in obese men and that leptin seems to be the best hormonal predictor of this blunted response to LH stimulation
  • The low basal 17-OH-P levels found in massively obese men are consistent with a global impairment of Leydig cell steroidogenic function in this group of subjects.
  • These findings indicate that obese men have a FM-related defect in the enzymatic conversion of 17-OH-P to T, which is revealed by hCG stimulation.
  • Other studies have investigated the adrenal function in male obesity and have shown that basal cortisol and 17-OH-progesterone levels tend to decrease with the increase in the degree of obesity
  • High E2 can inhibit the expression and activity of the 17,20-lyase and may be responsible for this steroidogenic lesion
  • However, stimulated E2 levels were not higher in the obese than in controls, excluding the fact that the lower androgen response was due to an increased aromatization of T to E2 and that estrogens have a major role in the observed defect of 17,20-lyase activity in obese men.
  • the percentage increase in the 17-OH-progesterone to T molar ratio paralleled the increase in leptin levels of obese men
  • Multiple regression analysis indicated that the best hormonal predictor of the obesity-related reduction in T and FT basal levels and androgen changes after hCG stimulation was serum leptin concentration
  • insulin has no negative influences on androgen production in obese men
  • insulin is known to have stimulatory actions on T production that have been demonstrated in obese and normal weight men (57) and in Leydig cells in culture
  • the negative correlation between insulin and basal T can be partly explained by the inhibitory action of insulin on SHBG production
  • hypogonadal men have higher circulating leptin levels compared with hypogonadal patients under effective androgen substitution therapy
  • The impaired androgen response to LH stimulus was due to a defect in the enzymatic conversion of 17-OH-progesterone to T, which was disclosed by a leptin-related increase in 17-OH-progesterone to T ratio
  • Estrogens, which are inhibitory modulators of LH pulsatility and bioactivity
  • Nathan Goodyear on 04 Sep 14
     
    Leptin appears to be a good marker of low Testosterone.  This study proposes that the mechanism of action is potentially 2 fold: first, a decrease in LH release by leptin (kisspeptin?) and 2nd, a directed decrease in Testosterone production by the leydig cells in the testes.
Nathan Goodyear

A strong association between biologically active testosterone and leptin in non-obese m... - 0 views

www.nature.com/...0801467a.html

leptin Testosterone hormone hormones obesity

shared by Nathan Goodyear on 22 Oct 14 - No Cached
  • strongly supports an association between levels of androgens and leptin in both men and women
  • The association between androgen levels and leptin seems to be dependent of fat distribution in men
  • There is a growing bulk of evidence suggesting that testosterone may influence leptin levels. Testosterone administration reduces leptin levels in hypogonadal27,28 and eugonadal men
  • ...5 more annotations...
  • testosterone suppression by GnRH agonist treatment of central precocious puberty in boys increases leptin levels
  • Testosterone levels decreased with increasing central obesity in healthy men, while they increase with increasing obesity in healthy women, the latter irrespective of menstrual status
  • this could be due to obesity-related hyperleptinemia that inhibits testosterone secretion at the testicular level.46,47 These changes, which are proposed to be components of the insulin resistance syndrome,48 are associated with increased risk for cardiovascular disease in both men and women
  • in the more obese subjects, the higher leptin levels due to increased adiposity might reduce secretion of testosterone
  • loss of regulation of leptin by testosterone in obese men and women could be an important feature of the insulin resistance syndrome
  • Nathan Goodyear on 22 Oct 14
     
    Leptin and Testosterone.  Interesting relationship that differs between the sexes.
Nathan Goodyear

Chronic exposure to Low dose bacterial lipopolysaccharide inhibits leptin signaling in ... - 0 views

www.ncbi.nlm.nih.gov/...PMC4523075

LPS lipopolysaccharides leptin CCK cholecystokinin metabolism weight appetite diet nutrition inflammation

shared by Nathan Goodyear on 04 Oct 17 - No Cached
  • Obesity and models of obesity induced by ingestion of HF-diet in rodents are associated with chronically elevated circulating levels of LPS
  • chronic low-dose administration of LPS induces leptin-resistance in vagal afferent neurons and abolition of CCK-induced inhibition of food intake
  • HF fat feeding has been shown to enhance gastrointestinal permeability promoting the translocation of LPS to the circulation
  • ...9 more annotations...
  • LPS leads to an increase in SOCS3 expression [20]. SOCS3 is a negative regulator of leptin signaling
  • We observed a significant increase in energy intake in the LPS-treated rats
  • the data provides a mechanism linking changes in gut microbiota induced by ingestion of HF diets to dysregulation of food intake and body weight
  • SOCS3 is an important mechanism by which leptin resistance develops in vagal afferent neurons and coincides with the onset of hyperphagia
  • Chronic low-dose LPS treatment induced TLR4 activation and MyD88 signaling in vagal afferent neurons, associated with increased SOCS3 expression and reduced leptin-signaling, characterized by the absence of leptin-induced pSTAT3.
  • We demonstrate that this chronic low dose LPS is sufficient to induce leptin–resistance in vagal afferent neurons, reduced sensitivity to the satiating effects of CCK, and loss of vagal afferent plasticity
  • it suggests that the increase in food intake and body weight we observed at week 6 in the LPS treated rats may be caused by LPS-induced leptin resistance.
  • chronic LPS treatment of mice for four weeks increased body weight
  • chronic LPS treatment of mice for four weeks increased subcutaneous fat
  • Nathan Goodyear on 04 Oct 17
     
    Very interesting study.  High fat diet in rats induced gut flora change that resulted in LPS which induced appetite through leptin resistance and reduced cholecystokinin signaling.
Nathan Goodyear

LeptiPro - Intelligent Weight Control - 0 views

www.leptinresearch.org

Leptin resistance obese overweight weight loss

shared by Nathan Goodyear on 08 Mar 11 - No Cached
  • "leptin resistance."
  • In order for leptin to control body weight and metabolism, it must do so from the hypothalamic centers in the brain,
  • When brain levels of leptin are low due to "leptin resistance" - even if there are high circulating blood levels of leptin - food cravings and weight gain occur because the body believes that it is hungry and goes into a state of continued fat storage.
  • ...2 more annotations...
  • By reversing "leptin resistance," through the blocking of PTP1 B, the function of the protein hormone leptin is restored so that the hypothalamic center can normally and effectively modulate body weight and metabolism.
  • Published studies demonstrate that the botanically derived phytochemical, isolated and purified single-peak Isoquinoline Alkaloid Berberine Hel, specifically and potently inhibits human Protein Tyrosine Phosphates 1B (PTP1 B).
  • Nathan Goodyear on 08 Mar 11
     
    Obese or struggling with weight?  look to Leptin
Nathan Goodyear

Triglycerides Induce Leptin Resistance at the Blood-Brain Barrier - 0 views

diabetes.diabetesjournals.org/...1253.full

leptin resistance triglycerides

shared by Nathan Goodyear on 12 Apr 11 - No Cached
  • Obesity is associated with leptin resistance
  • Resistance arises from impaired leptin transport across the blood-brain barrier (BBB)
  • Decreasing triglycerides may potentiate the anorectic effect of leptin by enhancing leptin transport across the BBB.
  • ...2 more annotations...
  • Starvation, like obesity, is accompanied by a decreased BBB transport rate of exogenous leptin
  • hypertriglyceridemia could explain impaired transport of leptin across the BBB in both starvation and obesity
  • Nathan Goodyear on 12 Apr 11
     
    elevated triglycerides and leptin resistance
Nathan Goodyear

Testosterone Substitution Normalizes Elevated Serum Leptin Levels in Hypogonadal Men: T... - 0 views

press.endocrine.org/...jcem.82.8.4174

leptin low T low Testosterone low T testosterone obese obesity men male hormone hormones

shared by Nathan Goodyear on 03 Nov 14 - No Cached
  • Nathan Goodyear on 03 Nov 14
     
    Men with low T and elevated Leptin, have Leptin normalized with Testosterone therapy.  In obese men, Leptin is inversely associated with Testosterone.  This points to more cause/effect relationship with low T, elevated Leptin, and obesity in men.
Nathan Goodyear

Mechanisms of Leptin Action and Leptin Resistance - Annual Review of Physiology, 70(1):537 - 0 views

www.annualreviews.org/...nurev.physiol.70.113006.100707

leptin resistance

shared by Nathan Goodyear on 21 Apr 11 - No Cached
  • The failure of elevated leptin levels to suppress feeding and mediate weight loss in common forms of obesity defines a state of so-called leptin resistance.
  • Nathan Goodyear on 21 Apr 11
     
    mechanisms of Leptin action and Leptin Resistance
Nathan Goodyear

Obesity and testicular function. [Mol Cell Endocrinol. 2010] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...19540307

obesity leydig cells Testosterone low T low Testosterone T SHBG LH leptin men male hormone hormones

shared by Nathan Goodyear on 04 Sep 14 - No Cached
  • Nathan Goodyear on 04 Sep 14
     
    This article, here only abstract available, points to low Testosterone as the effect and not the cause.  The cause being obesity.  An interesting association between leptin and low T is found.  Leptin is a hormone produced from adipocytes, this study found leptin receptors in the leydig cells of testes.  Thus, increased leptin production from increased abdominal adiposity can result in a decrease in 17,20 lyase activity and thus a direct inhibition of leydig cell Testosterone production.
Nathan Goodyear

Leptin and Androgens in Male Obesity: Evidence for Leptin Contribution to Reduced Andro... - 1 views

jcem.endojournals.org/...3673.long

low T testosterone low leptin resistance obesity men male hormone hormones

shared by Nathan Goodyear on 28 Aug 12 - No Cached
  • Nathan Goodyear on 28 Aug 12
     
    increased leptin production results in reduced testosterone production.  Link between leptin associated obesity and resultant low testosterone.
Nathan Goodyear

Leptin serves body as energy signal | Harvard Gazette - 0 views

news.harvard.edu/...n-serves-body-as-energy-signal

leptin body energy hormones thyroid

shared by Nathan Goodyear on 08 Mar 11 - No Cached
  • replacing leptin to physiologically normal levels during fasting fully restored testosterone to baseline, indicating that leptin regulates the hypothalamic-pituitary- gonadal axis that controls the release of testosterone and estrogen
  • Leptin clearly has some effect on the thyroid hormone axis,
  • including thyroid-stimulating hormone and the free-circulating form of thyroid
  • Nathan Goodyear on 08 Mar 11
     
    Leptin regulates hypothalamic-pituitary axis; and don't forget thyroid too.
Nathan Goodyear

Sex hormones, leptin and anthropometric indices in men - 0 views

www.jri.ir/...showarticle.aspx

leptin low T low Testosterone Testosterone BMI SHBG men male hormone hormones

shared by Nathan Goodyear on 27 Oct 14 - No Cached
  • Nathan Goodyear on 27 Oct 14
     
    Low Testosterone associated with increased leptin independent of BMI.  Increased leptin, low T, and SHBG were associated with increasing BMI in men.  Excluding BMI points to a more cause-effect relationship between elevated leptin and low T in men.
Nathan Goodyear

Fructose-induced leptin resistance exacerbates weight gain in response to subsequent hi... - 0 views

www.ncbi.nlm.nih.gov/...PMC2584858

fructose HFCS leptin leptin resistance diet nutrition obesity

shared by Nathan Goodyear on 05 Jun 16 - No Cached
  • Nathan Goodyear on 05 Jun 16
     
    Another rat model finds that high fructose intake causes leptin resistance and worsens leptin resistance.
Nathan Goodyear

Elevated Levels of Interleukin 6 Are Reduced in Serum and Subcutaneous Adipose Tissue o... - 0 views

jcem.endojournals.org/...3338.full

weight loss overweight obesity adipose tissue adipocytes IL-6 leptin inflammation

shared by Nathan Goodyear on 15 Mar 12 - No Cached
  • Nathan Goodyear on 15 Mar 12
     
    weight loss resulted in reduction in IL-6 and leptin.  The reduction of IL-6 reflects a decrease in inflammation. The reduction in leptin reflects an improved leptin sensitivity.
Nathan Goodyear

ScienceDirect - Physiology & Behavior : The role of leptin in leptin resistance and obe... - 0 views

www.sciencedirect.com/science

leptin resistance obesity weight loss

shared by Nathan Goodyear on 09 Mar 11 - No Cached
  • Nathan Goodyear on 09 Mar 11
     
    The role of leptin in leptin resistance and obesity
Nathan Goodyear

Expression of Functional Leptin Receptors in Rodent Leydig Cells: Endocrinology: Vol 14... - 0 views

press.endocrine.org/...endo.140.11.7088

leydig cells Testosterone hormone hormones leptin leptin resistance

shared by Nathan Goodyear on 31 Mar 15 - No Cached
  • Nathan Goodyear on 31 Mar 15
     
    mouse model finds leydig cells have leptin receptors.  Stimulation of the leptin receptors decreased leydig Testosterone production.
Nathan Goodyear

Testosterone: a metabolic hormone in health and disease - 0 views

joe.endocrinology-journals.org/...R25.full

male hormone hormones testosterone hypogonadal-obesity-adipocytokine hypothesis

shared by Nathan Goodyear on 08 May 13 - No Cached
  • E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production of GNRH and subsequent release of LH and FSH from the pituitary
  • Leptin, an adipose-derived hormone with a well-known role in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic GNRH neurons
  • In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes leptin resistant
  • ...39 more annotations...
  • there is evidence from animal studies that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
  • Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen status
  • Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic control following ADT
  • ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an increased risk of developing MetS and T2DM
  • Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated insulin levels and worsening glycaemic control
  • increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated with a decrease in Leydig cell testosterone secretion in men
  • The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
  • Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride levels
  • a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic men
  • up to 70% of the body's insulin sensitivity is accounted for by muscle
  • Testosterone deficiency is associated with a decrease in lean body mass
  • relative muscle mass is inversely associated with insulin resistance and pre-diabetes
  • GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal muscle cells following testosterone treatment at low dose and short-time incubations
  • local conversion of testosterone to DHT and activation of AR may be important for glucose uptake
  • inverse correlation between testosterone levels and adverse mitochondrial function
  • orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose from the intestine
  • (Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation during the fasting state.
  • Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular lipid, in particular diacylglycerol and/or ceramide in myocytes
  • In the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to testosterone
  • Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
  • oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell line
  • FFA decrease hepatic insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
  • Only one, albeit large-scale, population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis in men (Völzke et al. 2010)
  • This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to E2 and subsequent activation of ERα.
  • hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
  • visceral adipose tissue was inversely correlated with bioavailable testosterone
  • there was no change in visceral fat mass in aged men with low testosterone levels following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal areas when analysed by MRI (Frederiksen et al. 2012b)
  • ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective observational study (Hamilton et al. 2011)
  • Catecholamines are the major lipolysis regulating hormones in man and regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
  • deficiency of androgen action decreases lipolysis and is primarily responsible for the induction of obesity (Yanase et al. 2008)
  • may be some regional differences in the action of testosterone on subcutaneous and visceral adipose function
  • proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates liver production of CRP
  • observational evidence suggests that IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
  • TRT has been reported to significantly reduce these proinflammatory mediators
  • This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory response
  • testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis, decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly reduce fat mass and increase muscle mass
  • Early interventional studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters of insulin sensitivity and glucose control
  • Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement supports a key role of this hormone in glucose and lipid metabolism
  • Impaired insulin sensitivity in these three tissues is characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin to inhibit lipolysis in adipose tissue
  • Nathan Goodyear on 08 May 13
     
    Great review of the Hypogonadal-obesity-adipocytokine hypothesis.
Nathan Goodyear

Zinc May Regulate Serum Leptin Concentrations in Humans - 0 views

www.jacn.org/...270.full

Zinc Zn leptin IL-2 TNF-alpha obesity overweight

shared by Nathan Goodyear on 31 Aug 12 - No Cached
  • Nathan Goodyear on 31 Aug 12
     
    Zinc found to be associated with an increase in leptin.  Also, increased IL-2 and TNF-alpha found to be associated.  This has potential implications in obesity treatment: obviously not in those individuals that are leptin resistant.  
Nathan Goodyear

Leptin inhibits testosterone secretion from adult rat testis in vitro. - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...10320818

leptin Testosterone LH FSH

shared by Nathan Goodyear on 17 Jun 15 - No Cached
  • Nathan Goodyear on 17 Jun 15
     
    high leptin levels found to inhibit pituitary LH/FSH release.  Of note, high leptin levels inhibited leydig cell production of Testosterone following hCG stimulation.  This is a rat in vitro study.
Nathan Goodyear

Kent Holtorf: Long Term Weight Loss - More Than Will Power? - 0 views

www.huffingtonpost.com/...-weight-loss---m_b_192933.html

leptin reverse T3 weight loss

shared by Nathan Goodyear on 09 Mar 11 - No Cached
  • which is a major reason for the regaining of lost weight with dieting as well being the mechanism behind stress induced weight gain (it is not due to increased cortisol).
  • f greater than 10, it demonstrates there is a degree of leptin resistance contributing to an inability to lose weight
  • that it is difficult to lose weight with leptin resistance. High carbohydrate diets and in particular high-fructose corn syrup is shown to significantly increase leptin resistance and is a likely mechanism that high fructose corn syrup is associated with obesity
  • ...9 more annotations...
  • inactive thyroid hormone called thyroxine
  • it is problem inside the cell that the inactive T4 is not converted to T3 but rather to a mirror image of T3 called reverse T3. The reverse T3 has the opposite effect of T3, blocking the effects of T3 and lowering rather than increasing metabolism.
  • Studies are showing that stress and dieting (especially yo-yo dieting) can set this hormone into action as well as chronic illness such as diabetes, chronic fatigue syndrome and fibromyalgia.
  • As soon as the body senses a reduction in calories, the production of reverse T3 is stimulated to lower metabolism
  • With chronic dieting or stress, the body often stays in this "starvation mode" with elevated levels of reverse T3 and decreased levels of T3, which is a major reason for the regaining of lost weight with dieting as well being the mechanism behind stress induced weight gain (it is not due to increased cortisol).
  • which is a major reason for the regaining of lost weight with dieting as well being the mechanism behind stress induced weight gain (it is not due to increased cortisol).
  • which is a major reason for the regaining of lost weight with dieting as well being the mechanism behind stress induced weight gain (it is not due to increased cortisol).
  • Studies are showing that such standard testing will miss 80% of thyroid dysfunction
  • ree T3/reverse T3 ratio
  • Nathan Goodyear on 09 Mar 11
     
    Fantastic review by Dr. Holtorf on reverse T3, leptin, and weight loss
Nathan Goodyear

Leptin and the pituitary-thyroid axis: a comparative study in lean, obese, hypothyroid ... - 0 views

onlinelibrary.wiley.com/...abstract

thyroid hypothyroid hypothyroidism leptin obesity overweight

shared by Nathan Goodyear on 08 Mar 11 - No Cached
  • The data are consistent with the hypothesis that leptin and the pituitary–thyroid axis interact in the euthyroid state, and that hypothyroidism reversibly increases leptin concentrations
  • Nathan Goodyear on 08 Mar 11
     
    thyroid and leptin interact to control weight
1 - 20 of 134 Next › Last »
Showing 20▼ items per page