Hospital-diagnosed overweight and obesity related to cancer risk: a 40-year Danish cohort study.

BACKGROUND: Obesity is associated with metabolic abnormalities that predispose patients to increased cancer risk. Contemporary data on the long-term risk of specific cancers are sparse among patients with hospital-diagnosed overweight and obesity. OBJECTIVES: To examine the overall cancer incidence and specific site-related cancer incidences among patients with overweight and obesity, compared to the general Danish population. METHODS: For this 40-year (1977-2016), nationwide, Danish cohort study, we reviewed medical databases to identify individuals with hospital-based overweight and obesity diagnoses. We computed age- and gender-standardized incidence ratios (SIRs) for subsequent cancer compared to the general population. RESULTS: We observed 20 706 cancers among 313 321 patients diagnosed with overweight and obesity (median age 43 years; median follow-up 6.7 years, range 1-40 years) compared to the 18 480 cancers expected; thus, the SIR was 1.12 [95% confidence interval (95% CI): 1.11-1.14]. The SIR associated with overweight and obesity was increased with concomitant comorbidities, like type 2 diabetes (SIR: 1.18; 95% CI: 1.13-1.23) and alcoholism-related diseases (SIR: 1.62; 95% CI: 1.45-1.82). The SIR was 1.31 (95% CI: 1.28-1.34) for cancers previously identified as obesity-related, including pancreatic (SIR: 1.38; 95% CI; 1.27-1.49) and postmenopausal breast cancer (SIR: 1.14; 95% CI: 1.09-1.19). Obesity/overweight status also elevated the SIRs for haematological (SIR: 1.24; 95% CI: 1.18-1.29) and neurological cancers (SIR: 1.19; 95% CI: 1.11-1.27]. In contrast, SIRs were 1.01 (95% CI: 0.97-1.05) for immune-related cancers, 0.88 (95% CI: 0.82-0.95) for malignant melanoma, and 0.88 (95% CI: 0.85-0.92) for hormone-related cancers, other than postmenopausal breast cancer. CONCLUSION: In this large cohort study, overweight and obesity was associated with increased risk of several common cancers.

Diabetic retinopathy in people with Type 2 diabetes and obesity treated by Roux-en-Y gastric bypass compared with non-operated controls: with focus on the role of diabetes remission in a cross-sectional and a 6-year follow-up study.

AIM: Whether or not Roux-en-Y gastric bypass (RYGB) and the derived metabolic improvements are beneficial to diabetic retinopathy is controversial. We aimed to determine the presence and development of retinopathy in individuals with obesity and Type 2 diabetes treated by RYGB compared with non-operated controls, and to determine the role of diabetes remission. METHODS: We graded fundus photography using the Wisconsin Epidemiologic Study of Diabetic Retinopathy in 96 individuals with obesity and Type 2 diabetes treated by RYGB 6 years after surgery compared with 48 non-operated controls. In a subsample, we investigated the development of retinopathy over time. In the secondary analysis, we divided the RYGB group according to diabetes remission. RESULTS: RYGB surgery was not statistically associated with less retinopathy [relative risk (RR) 0.82, 95% CI 0.59 to 1.14], when adjusted for diabetes duration, sex, age and BMI. During 5.9 years of follow-up, retinopathy grading in the RYGB group was unchanged, whereas the control group displayed worse grading by 0.69 steps (95% CI 0.18 to 1.19). The RYGB group with diabetes remission (52%) showed a trend towards less retinopathy [adjusted RR (aRR) 0.45; 95% CI 0.19 to 1.06] than controls, and less retinopathy (aRR 0.33; 95% CI 0.11 to 0.94) than the RYGB group without remission in the cross-sectional data. CONCLUSIONS: In a cross-sectional setting, individuals with Type 2 diabetes treated by RYGB showed a tendency towards less retinopathy than non-operated controls, in particular diabetes remission following RYGB was associated with less retinopathy. Moreover after 5.9 years, retinopathy in the RYGB group had progressed less than in the control group. (Clinical Trial Registry No: NCT02625649).

Expression of vitamin D-metabolizing enzymes in human adipose tissue -- the effect of obesity and diet-induced weight loss.

OBJECTIVE: Low vitamin D (VD) levels are common in obesity. We hypothesized that this may be due to metabolism of VD in adipose tissue (AT). Thus, we studied (1) whether the VD-metabolizing enzymes were expressed differently in AT of lean and obese individuals and in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), and (2) whether their expression was influenced by weight loss. METHODS: Samples of SAT and VAT were analyzed for expression of the vitamin-D-25-hydroxylases CYP2R1, CYP2J2, CYP27A1 and CYP3A4, the 25-vitamin-D-1α-hydroxylase CYP27B1, the catabolic vitamin-D-24-hydroxylase CYP24A1, and the vitamin D receptor, using reverse transcriptase-PCR. Moreover, plasma 25-hydroxy-vitamin D (25OHD) level was measured and related to the expression of these enzymes. Samples of SAT and VAT from 20 lean women and 20 obese women, and samples of SAT from 17 obese subjects before and after a 10% weight loss were analyzed. RESULTS: A plasma 25OHD level <50 nmol l(-1) was highly prevalent in both lean (45%) and obese (90%) women (P<0.01). Plasma 25OHD increased by 27% after weight loss in the obese individuals (P<0.05). Expression levels of the 25-hydroxylase CYP2J2 and the 1α-hydroxylase CYP27B1 were decreased by 71% (P<0.0001) and 49% (P<0.05), respectively, in SAT of the obese. CYP24A1 did not differ between lean and obese women, but the expression was increased by 79% (P<0.05) after weight loss. CONCLUSION: Obesity is characterized by a decreased expression of the 25-hydroxylase CYP2J2 and the 1α-hydroxylase CYP27B1 in SAT, whereas the catabolic CYP24A1 does not differ between lean and obese women. However, the expression of CYP24A1 is increased after weight loss. Accordingly, AT has the capacity to metabolize VD locally, and this can be dynamically altered during obesity and weight loss.

Investigations of the anti-inflammatory effects of vitamin D in adipose tissue: results from an in vitro study and a randomized controlled trial.

Inflammation is a key feature of obesity and type 2 diabetes. The active vitamin D metabolite, 1,25-dihydroxyvitamin D [1,25(OH)2D], modulates the inflammation in vitro. We studied whether inflammation in adipose tissue (AT) cultures could be reduced by incubation with 1,25(OH)2D in vitro, or by oral treatment with vitamin D in vivo in obese subjects with low plasma levels of 25-hydroxyvitamin D. Samples of subcutaneous AT were stimulated with IL-1ß to induce inflammation. In the in vitro study, samples were concomitantly incubated with or without 1,25(OH)2D, and analyzed for mRNA and protein levels of inflammatory markers IL-6, IL-8, and MCP-1. In the in vivo study, samples of subcutaneous AT from obese subjects obtained before and after treatment with 7,000 IU of vitamin D daily or placebo in a randomized controlled trial were stimulated with IL-1ß. The samples were analyzed for AT gene expression and compared with plasma markers of inflammation. In the in vitro study, concomitant incubation with 1,25(OH)2D reduced mRNA levels of MCP-1 by 45% (p=0.01), of IL-6 by 32% (p=0.002), and of IL-8 by 34% (p=0.03), and reduced secretion of IL-8 protein by 18% (p=0.005). In vivo treatment with vitamin D did not reduce AT expression or circulating levels of MCP-1, IL-6, or IL-8. 1,25(OH)2D has significant anti-inflammatory effects in AT in vitro. However, a similar reduction in AT and systemic inflammation cannot be obtained by oral treatment with vitamin D in obese subjects.

Strength training and testosterone treatment have opposing effects on migration inhibitor factor levels in ageing men.

BACKGROUND: The beneficial effects of testosterone treatment (TT) are debated. METHODS: Double-blinded, placebo-controlled study of six months TT (gel) in 54 men aged 60-78 with bioavailable testosterone (BioT) <7.3 nmol/L and waist >94 cm randomized to TT (50-100 mg/day, n = 20), placebo (n = 18), or strength training (ST) (n = 16) for 24 weeks. Moreover, the ST group was randomized to TT (n = 7) or placebo (n = 9) after 12 weeks. OUTCOMES: Chemokines (MIF, MCP-1, and MIP-1 α ) and lean body mass (LBM), total, central, extremity, visceral, and subcutaneous (SAT) fat mass established by DXA and MRI. Results. From 0 to 24 weeks, MIF and SAT decreased during ST + placebo versus placebo, whereas BioT and LBM were unchanged. TT decreased fat mass (total, central, extremity, and SAT) and increased BioT and LBM versus placebo. MIF levels increased during TT versus ST + placebo. ST + TT decreased fat mass (total, central, and extremity) and increased BioT and LBM versus placebo. From 12 to 24 weeks, MCP-1 levels increased during TT versus placebo and MCP-1 levels decreased during ST + placebo versus placebo. CONCLUSION: ST + placebo was associated with decreased MIF levels suggesting decreased inflammatory activity. TT may be associated with increased inflammatory activity.

The effect of weight loss on serum mannose-binding lectin levels.

BACKGROUND: Serum levels of the mannose-binding lectin (MBL), which is an activator of the complement system, have been considered as a pathogenic factor in a broad range of diseases, and means of modulating MBL are therefore being evaluated. In this study we examine the effects of weight loss on MBL levels, and in continuation of this if MBL is synthesized in human adipose tissue. METHODS: 36 nondiabetic obese subjects received a very low-calorie diet (VLCD) of 800 kcal/day for 8 weeks. Blood samples were collected at baseline and after VLCD. Furthermore, we measured MBL mRNA levels by the real-time RT-PCR on human adipose tissue compared to liver tissue. RESULTS: The mean body weight was reduced from 106.3 ± 2.6 kg to 92.8 ± 2.4 kg, P < 0.0001. Median MBL at baseline was 746 µg/L (IQR 316-1190) versus 892 µg/L (IQR 336-1511) after 8 weeks, P = 0.23. No correlations were found between weight loss and changes in MBL (r = -0.098, P = 0.57). MBL real-time RT-PCR showed no expression of mRNA in adipose tissue, but as expected a good expression in liver tissue was seen. CONCLUSIONS: MBL levels are not affected by weight loss and MBL is not synthesized in human adipose tissue.

Investigations of the human endocannabinoid system in two subcutaneous adipose tissue depots in lean subjects and in obese subjects before and after weight loss.

CONTEXT: Endocannabinoids (ECs) have a role in obesity by affecting appetite and through peripheral effects. Obesity is associated with a dysregulation of the endocannabinoid system (ECS). OBJECTIVE: We aimed to determine the ECS in subcutaneous adipose tissue (AT) in obese subject and investigate the influence of diet-induced weight loss on this system. DESIGN: The obese study participants underwent a 12 weeks diet regimen resulting in 10-12% weight loss. All study participants underwent fasting blood samples and AT biopsies from abdomen and gluteal region, the obese subjects both before and after weight loss. SETTING AND PARTICIPANTS: A total of 21 healthy obese individuals (10 men/11 women, age 39.5 ± 1.6 years, body mass index (BMI): 37.5 ± 0.8 kg m(-2)) and 21 age- and gender-matched lean subjects (BMI: 23.8 ± 0.4 kg m(-2)) were studied. MAIN OUTCOME MEASURES: The activity of ECS in AT was determined by measuring arachidonoyl glycerol (2-AG) and N-arachidonoylethanolamine/anandamide in AT by mass spectrometry and gene expressions of enzymes and receptors involved in the ECS. RESULTS: The EC, 2-AG was reduced in obese individuals in the gluteal AT depot (P<0.01). Moreover, 2-AG increased in both depots in the obese subjects following weight loss (P<0.05). The gene expression of the CB1 was either not affected by the obese state (in the gluteal AT depot) or reduced (in the abdominal depot, P<0.05) and significantly affected by weight loss. The expression of the degrading enzymes FAAH, FAAH2, MGL and MGL2 was differently affected by obesity, AT depot and weight loss. CONCLUSION: We found reduced levels of 2-AG in subcutaneous AT in obesity, which increased after weight loss. In abdominal AT, the low CB1 expression was normalised after weight loss, whereas in gluteal AT the CB1 expression was reduced after weight loss. These findings support the concept of a dysregulated ECS in AT in association with obesity.

Anti-inflammatory effect of resveratrol on adipokine expression and secretion in human adipose tissue explants.

OBJECTIVE: Human obesity is closely associated with a state of chronic low-grade inflammation, which also involves the adipose tissue with enhanced production of bioactive substances (adipokines). Calorie restriction (CR) reduces adipocytokine production and improves metabolic profile in rodents. Some of these effects are mediated through activation of the sirtuin 1 (Sirt1) enzyme, and in this study, we investigate whether the natural phytoalexin, resveratrol (RSV), which is a potent Sirt1 activator, has anti-inflammatory effects in human adipose tissue explants. DESIGN: The effect of RSV on interleukin 1ß (IL1ß)-induced change of adipokine mRNA gene expression and secretion were measured in human adipose tissue explants. RESULTS: Exposure of human adipose tissue in vitro to IL1ß for 24 h increased secretion of the proinflammatory adipokines IL6, IL8 and monocyte chemoattractant protein 1 (MCP-1) 3-7.7-fold (P<0.05) and increased IL6, IL8, MCP-1, IL1ß and PAI-1 mRNA expression 1.3-7.2-fold (P<0.05) accordingly. Concomitant incubations with RSV reversed the IL1ß-stimulated secretion (16-36%) and gene expression (25-48%) of these adipokines. IL1ß reduced adiponectin mRNA expression (40%), a decrement that was reversed by RSV treatment. Similar effects were observed in differentiated human preadipocytes in primary culture, indicating that human adipocytes are a potential target for RSV effects. Finally, the effects were neutralized by sirtinol, a Sirt1 inhibitor. CONCLUSION: This study is the first to show anti-inflammatory effects of RSV on adipokine expression and secretion in human adipose tissue in vitro through the SIRT1 pathway. Thus, RSV is hypothesized to possess beneficial effects and might improve the metabolic profile in human obesity.

Reduced cannabinoid receptor 1 protein in subcutaneous adipose tissue of obese.

BACKGROUND: Cannabinoid 1 receptors are identified in various tissues involved in the internal metabolism including adipose tissue and the endocannabinoid system is claimed to be overactive in the obese state. To study the potential involvement of cannabinoid receptor 1 in the endocannabinoid system over-activity in adipose tissue in the obese state, we investigated the cannabinoid receptor 1 levels in adipose tissue from different fat depots in lean and obese humans. MATERIALS AND METHODS: The adipose tissue samples were analysed by Western blot and by RT-PCR. RESULTS: Both the gene expression and the protein of cannabinoid receptor 1 were lower in subcutaneous abdominal adipose tissue from obese subjects as compared with lean subjects (P < 0.01 and P = 0.058). Moreover, in lean subjects, the level of cannabinoid receptor 1 was significantly higher in subcutaneous adipose tissue compared with visceral adipose tissue (P < 0.05) for both gene expression and protein. The level of cannabinoid receptor 1 was similar between the two depots in obese subjects. The expression of cannabinoid receptor 1 was higher in subcutaneous gluteal adipose tissue as compared with subcutaneous abdominal adipose tissue (P < 0.05). CONCLUSION: We found in lean subjects, a robust lower level of cannabinoid receptor 1 in visceral adipose tissue compared with subcutaneous adipose tissue (both RNA and protein levels), but similar levels of cannabinoid receptor 1 between the two depots in obese subjects. Our present findings do not indicate that cannabinoid receptor 1 is directly involved in the endocannabinoid system over-activity in adipose tissue in obesity.

Early changes in vitamin B12 uptake and biomarker status following Roux-en-Y gastric bypass and sleeve gastrectomy.

BACKGROUND & AIMS: Bariatric surgery increases the risk of micronutrient deficiencies, including vitamin B12 (B12) deficiency. We analysed early changes in biomarkers of B12 status following bariatric surgery. METHODS: We prospectively included adult patients (n = 27) referred for either Roux-en-Y Gastric Bypass (RYGB) (n = 19) or Sleeve Gastrectomy (SG) (n = 8). Blood samples were drawn before surgery and 2 and 6 months following surgery for measurement of B12, holotranscobalamin (holoTC), and methylmalonic acid (MMA). The B12 absorption capacity was estimated from the increase in plasma holoTC two days after a standardised oral B12 challenge. RESULTS: B12 status decreased following both RYBG and SG. While a decrease in plasma B12 was not evident until 6 months postoperatively, we observed a statistically significant decrease in plasma holoTC and increase in MMA already 2 months postoperatively. These changes were more pronounced at 6 months post surgery. Correspondingly, the B12 absorption capacity was decreased following surgery. CONCLUSIONS: HoloTC and MMA were superior to B12 to detect early changes in B12 status following bariatric surgery. Our data challenge the current concept that liver B12 stores secure long-term maintenance of B12 status. They indicate that B12 treatment in pharmacological doses may be warranted immediately after surgery.

Changes in Circulating BDNF in relation to Sex, Diet, and Exercise: A 12-Week Randomized Controlled Study in Overweight and Obese Participants.

Circulating BDNF is higher in women than in men and suggested to be affected by changes in food intake, body weight, and exercise. The purpose of this study was to compare BDNF concentrations in women and men during a 12-week weight loss intervention. Using a previously published 12-week randomized study, serum BDNF was assessed at baseline and after 12 weeks using an enzyme-linked immunosorbent assay method. Fifty overweight or obese but healthy individuals (26 women, mean age of 36.4 ± 7.9 years; 24 men, mean age of 38.0 ± 5.9 years) were included and allocated into three groups: exercise-only (EXO; 12 weeks of aerobic exercise and isocaloric diet), diet-only (DIO; 8 weeks of very low energy diet (VLED 600 kcal/day) followed by a 4-week weight maintenance diet), or diet and exercise (DEX; 12 weeks of aerobic exercise in parallel with 8 weeks of VLED (800 kcal/day) followed by a 4-week weight maintenance diet). At baseline, BDNF levels were 25% higher in women compared to men (p=0.006). Body weight was reduced in all intervention groups (p < 0.006). Exercise (EXO group) induced a 22% reduction in circulating BDNF in men (p=0.037) and women (p=0.080). In the DIO and DEX groups, a significant reduction in BDNF levels (29.9%; p=0.035 and 32.5%; p=0.003, respectively) was observed in women but not in men. In conclusion, circulating BDNF was significantly changed by diet alone or combined with exercise in women and only by exercise alone in men. This suggests that changes in circulating BDNF depend on weight loss methods (diet/exercise) as well as sex.

Low Sirt1 expression, which is upregulated by fasting, in human adipose tissue from obese women.

OBJECTIVE: Calorie restriction increases the life span in a number of different organisms. This effect is dependent upon activation of the Sirt1 enzyme, and many of the beneficial effects of calorie restriction can be mimicked using resveratrol, which activates the Sirt1 enzyme. Nothing is known about this system in human adipose tissue; therefore, we investigated this system in human adipose tissue. DESIGN: Sirt1 mRNA was measured in adipose tissue biopsies from human volunteers before and after 6 days of total fasting. In addition, adipose tissue from lean and obese individuals was compared and in vitro investigations were performed. RESULTS: Long-term total fasting (6 days) of nine human volunteers increased Sirt1 mRNA expression in subcutaneous adipose tissue more than twofold (0.197-0.454 arbitrary units, P<0.05). Likewise, lean women (n=12) had more than twofold higher Sirt1 expression in subcutaneous adipose tissue compared to obese women (n=12; 0.33-0.73 arbitrary units, P<0.05). Sirt1 was equally expressed in the stroma-vascular fraction and the isolated adipocyte fraction. Finally, in vitro, we demonstrated that resveratrol (a Sirt1 activator) significantly enhanced the lipolytic effect of epinephrine in human adipose tissue (P<0.05). CONCLUSION: Human adipose tissue contains Sirt1 and the expression of Sirt1 can be regulated by calorie restriction as in other species. Furthermore, we demonstrated that resveratrol affects human fat-cell metabolism similar to the effects in rodents (that is, increased epinephrine induced lipolysis). These findings indicated that the beneficial effects of calorie restriction in humans might involve the activation of Sirt1. Thus, based on these findings, we propose that Sirt1 might play important roles for the beneficial effects of calorie restriction in humans.

Weight history of patients with newly diagnosed Type 2 diabetes.

AIMS: To estimate and illustrate how the 10 years of weight change immediately preceding diabetes diagnosis vary with weight at the age of 20 years and with socio-demographic variables, risk factors and comorbidities at diagnosis. METHODS: Data were from a population-based cohort of 1320 persons newly diagnosed with diabetes aged > or = 40 years. Patients' weight at diagnosis was measured by the doctor, while patients recalled their weight approximately 1, 5 and 10 years prior to diagnosis and at age 20 years. RESULTS: Median weight gain from age 20 years to diabetes diagnosis at median age 65.3 years was 14.7 kg (interquartile range 6.0-23.0). Women gained weight more than men, and the lower the weight at age 20 years, the greater the weight gain. The average weight gain from 10 years prior to diabetes diagnosis until diagnosis, however, was only 1 kg and decreased markedly with age. These 10 years of weight change were also associated with sex and the following baseline characteristics: diagnostic plasma glucose, urinary glucose, urinary albumin, fasting triglycerides, systolic blood pressure, smoking habits, and presence of diabetic retinopathy. CONCLUSIONS: The results add to the evidence that it is important to advise young patients in particular, especially women, who have gained and sustained considerable weight to curb this upward weight trend in order to prevent the development of diabetes.

Glucose transport and metabolism in adipocytes from newly diagnosed untreated insulin-dependent diabetics. Severely impaired basal and postinsulin binding activities.

Previous studies have shown cellular insulin resistance in conventionally treated insulin-dependent diabetics. To determine whether insulin resistance is also present in insulin-dependent diabetics before the commencement of insulin therapy, we studied nine newly diagnosed untreated insulin-dependent diabetics and nine control subjects. Insulin binding to adipocytes, monocytes, and erythrocytes was normal in the diabetic individuals. Basal (noninsulin stimulated) glucose transport rate was normal, whereas the maximal insulin responsiveness of glucose transport was severely impaired (P less than 0.02). Insulin sensitivity as judged by left or rightward shifts in the insulin dose-response curves was unchanged. Moreover, the basal lipogenesis rate measured at a glucose concentration of 0.5 mmol/liter was decreased in the diabetics (P less than 0.05), and the maximal insulin responsiveness of lipogenesis was also reduced (P less than 0.05). We conclude that fat cells from untreated insulin-deficient diabetics are insulin resistant. The major defects are (1) reduced maximal insulin responsiveness of glucose transport and conversion to lipids that are postbinding abnormalities, and (2) reduced basal glucose conversion to lipids.

Amino acid supplementation is anabolic during the acute phase of endotoxin-induced inflammation: A human randomized crossover trial.

BACKGROUND & AIMS: Inflammation is catabolic and causes muscle loss. It is unknown if amino acid supplementation reverses these effects during the acute phase of inflammation. The aim was to test whether amino acid supplementation counteracts endotoxin-induced catabolism. METHODS: Eight young, healthy, lean males were investigated three times in randomized order: (i) normal conditions (Placebo), (ii) endotoxemia (LPS), and (iii) endotoxemia with amino acid supplementation (LPS + A). Protein kinetics were determined using phenylalanine, tyrosine, and urea tracers. Each study day consisted of a four-hour non-insulin stimulated period and a two-hour hyperinsulinemic euglycemic clamp period. Muscle biopsies were collected once each period. RESULTS: Endotoxin administration created a significant inflammatory response (cytokines, hormones, and vital parameters) without significant differences between LPS and LPS + A. Whole body protein breakdown was elevated during LPS compared with Placebo and LPS + A (p < 0.05). Whole body protein synthesis was higher during LPS + A than both Placebo and LPS (p < 0.003). Furthermore, protein synthesis was higher during LPS than during Placebo (p < 0.02). Net muscle phenylalanine release was markedly decreased during LPS + A (p < 0.004), even though muscle protein synthesis and breakdown rates did not differ significantly between interventions. LPS + A increased mammalian target of rapamycin (mTOR) phosphorylation (p < 0.05) and eukaryotic translation factor 4E-binding protein 1 (4EBP1) phosphorylation (p = 0.007) without activating AMPK or affecting insulin signaling through Akt. During insulin stimulation net muscle phenylalanine release and protein degradation were further reduced. CONCLUSIONS: Amino acid supplementation in the acute phase of inflammation reduces whole body and muscle protein loss, and this effect is associated with activation of mTOR and downstream signaling to protein synthesis through mTORC1, suggesting a therapeutic role for intravenous amino acids in inflammatory states. CLINICAL TRIAL REGISTRY: The Central Denmark Region Ethics Commitee (1-10-71-410-12) www.clinicaltrials.gov (identification number NCT01705782).

Characterization of nuclear corticosteroid receptors in rat adipocytes. Regional variations and modulatory effects of hormones.

The corticosteroid receptor was investigated in isolated rat adipocytes with a new technique which characterizes the corticosteroid receptors that can be activated and tightly bound to the nucleus. The binding reaction with [3H]triamcinolone was performed with intact isolated adipocytes and the radioactivity associated with nucleus was subsequently determined after cell lysis. Scatchard analysis revealed a homogeneous class of nuclear corticosteroid receptors in rat epididymal adipocytes with an apparent Kd of 4.93 +/- 1.5 nM and a Bmax of 21.8 +/- 6.6 fmol/10(6) cells corresponding to about 13,000 receptors per nucleus. The corticosteroid binding exhibited regional variations in isolated adipocytes. The highest receptor number was found in epididymal adipocytes (Bmax 25.8 +/- 3.9 fmol/10(6) cells) whereas there were significantly lower nuclear binding sites in perirenal adipocytes (16.5 +/- 5.5 fmol/10(6) cells) (P less than 0.05) and subcutaneous adipocytes (4.8 +/- 1.5 fmol/10(6) cells) (P less than 0.01). The apparent affinity in the three fat depots were similar with Kd values about 4 nM. The nuclear corticosteroid receptor in adipocytes was steroid specific, as neither unlabelled estradiol nor testosterone were able to displace the [3H]triamcinolone binding at concentrations up to 100 microM. However, unlabelled progesterone and promegestrone (R5020) were able to compete with triamcinolone-binding (by 50-80%). In order to investigate whether the nuclear corticosteroid binding in adipocytes were under influence of other hormones we examined the effects of lipolytic and antilipolytic compounds on the binding. Preincubation with isoproterenol and dibutryl-cAMP for 1 h was able to decrease the corticosteroid binding by 30-50%. However, the antilipolytic hormone insulin had no effect in preincubations performed for up to 2 h. In conclusion, high affinity nuclear corticosteroid receptors were found in rat adipocytes. These receptors exhibited regional variations and were modulated by lipolytic hormones.

Nuclear estradiol binding in rat adipocytes. Regional variations and regulatory influences of hormones.

The nuclear estrogen receptor was characterised in isolated rat adipocytes. The binding reaction with [3H]estradiol was performed with intact isolated rat adipocytes and the radioactivity associated with the nucleus was subsequently determined after cell lysis. The nuclear uptake of [3H]estrogen in rat adipocytes was temperature dependent and steroid specific. The steady-state binding was achieved after 30 min at 37 degrees C and was constant for several hours. Estradiol was found to bind to a homogeneous class of nuclear receptors in epididymal adipocytes with an apparent Kd of 3.1 +/- 0.76 nM and a Bmax of 7.98 +/- 1.11 fmol/10(6) cells corresponding to about 4800 receptors per nucleus. The estradiol binding exhibited regional variations in isolated adipocytes. In lean rats the highest receptor number was found in epididymal adipocytes, whereas there was a significantly lower number of nuclear binding sites in perirenal and subcutaneous adipocytes (P less than 0.05), unlike in older and more obese rats where the nuclear estradiol binding was greatest in adipocytes from the perirenal fat depot. Incubations with isoproterenol (10 microM) and dibutyryl-cAMP (2.5 mM) both reduced estradiol binding by 56% (P less than 0.005), while insulin (1 nM) enhanced the estradiol binding by 37% (P less than 0.01). In conclusion, a specific and high affinity nuclear estradiol receptor was demonstrated in rat adipocytes and regional differences in nuclear estradiol binding were detected. Furthermore, it was demonstrated that nuclear estradiol binding could be modulated by other agents known to affect adipocyte metabolism.

Effects of prostaglandin E2, indomethacin and adenosine deaminase on basal and insulin-stimulated glucose metabolism in human adipocytes.

The effects of prostaglandin E2 were studied on glucose metabolism (3-O-methylglucose transport, CO2 production and lipogenesis) in human adipocytes. Initially, the effects of endogenously produced adenosine and prostaglandins were indirectly demonstrated by using adenosine deaminase and indomethacin in the incubations. From these studies it was found that adenosine deaminase (5 micrograms/ml) had a pronounced effect on adipocyte glucose metabolism in vitro. In the basal (nonhormonal-stimulated) state, glucose transport, CO2 production and lipogenesis were inhibited by about 30% (P less than 0.05). Furthermore, adenosine deaminase significantly inhibited the isoproterenol- and insulin-stimulated CO2 production and lipogenesis (P less than 0.01). Indomethacin (50 microM) had a consistently inhibitory effect on the insulin-stimulated CO2 production (P less than 0.05), whereas indomethacin had no significant effects on basal or isoproterenol-stimulated glucose metabolism. In contrast to the relatively minor effect of endogenous prostaglandins, the addition of exogenous prostaglandin E2 significantly stimulated the glucose transport, glucose oxidation and lipogenesis in human adipocytes, especially in the presence of adenosine deaminase. Half-maximal stimulation was obtained at prostaglandin E2 concentrations of 2.2, 0.8 and 0.8 nM, respectively. The effect of prostaglandin E2 was specific, since the structurally related prostaglandin, prostaglandin F2 alpha, had practically no effect on glucose metabolism. The maximal effect of prostaglandin E2 (1 microM) on glucose metabolism was 30-35% of the maximal insulin (1 nM) effect. When insulin and prostaglandin E2 were added together, the effect of prostaglandin E2 on glucose metabolism was additive at all insulin concentrations tested.

Adiponectin: action, regulation and association to insulin sensitivity.

Adiponectin is a novel adipocyte-specific protein, which, it has been suggested, plays a role in the development of insulin resistance and atherosclerosis. Although it circulates in high concentrations, adiponectin levels are lower in obese subjects than in lean subjects. Apart from negative correlations with measures of adiposity, adiponectin levels are also reduced in association with insulin resistance and type 2 diabetes. Visceral adiposity has been shown to be an independent negative predictor of adiponectin. Thus, most features of the metabolic syndrome's negative associations with adiponectin have been shown. Adiponectin levels seem to be reduced prior to the development of type 2 diabetes, and administration of adiponectin has been accompanied by lower plasma glucose levels as well as increased insulin sensitivity. Furthermore, reduced expression of adiponectin has been associated with some degree of insulin resistance in animal studies indicating a role for hypoadiponectinaemia in relation to insulin resistance. The primary mechanisms by which adiponectin enhance insulin sensitivity appears to be through increased fatty acid oxidation and inhibition of hepatic glucose production. Adiponectin levels are increased by thiazoledinedione treatment, and this effect might be important for the enhanced insulin sensitivity induced by thiazolidinediones. In contrast, adiponectin levels are reduced by pro-inflammatory cytokines especially tumour necrosis factor-alpha. In summary, adiponectin in addition to possible anti-inflammatory and anti-atherogenic effects appears to be an insulin enhancer, with potential as a new pharmacologic treatment modality of the metabolic syndrome and type 2 diabetes.

Improved in vivo insulin effect during continuous subcutaneous insulin infusion in patients with IDDM.

It has recently been shown that conventionally treated IDDMs are insulin resistant. Using the insulin clamp technique, we studied the influence of metabolic status on the in vivo insulin effect in these patients. Eleven IDDMs, treated conventionally with diet and insulin for 10.7 +/- 5.6 yr, were studied before and after continuous subcutaneous insulin infusion (CSII) treatment (with a portable pump) for 6 mo. We found that conventionally treated diabetic subjects were extremely insulin resistant with regard to peripheral glucose uptake. Glucose uptake, at an insulin concentration of about 80 microU/ml, was 4.3 +/- 2.0 mg/kg X min before treatment compared with 11.5 +/- 4.0 mg/kg X min in normals (P less than 0.01). After pump treatment for 6 mo, metabolic control improved significantly (HbA1c decreased from 8.9 +/- 1.9% to 7.4 +/- 1.2%, P less than 0.01) and, parallel to that, glucose uptake increased about 80% to 7.5 +/- 3.5 mg/kg X min (P less than 0.01). The mean daily plasma FFA level decreased from 0.32 +/- 0.10 mmol/L to 0.21 +/- 0.07 mmol/L (P less than 0.01); this variable was negatively correlated to the glucose clearance rate (r = -0.62, P less than 0.01). There was no statistically significant change in mean daily plasma insulin and plasma growth hormone levels or in 24-h cortisol excretion in the urine (P greater than 0.1). The insulin binding capacity of serum IgG was also unchanged, and there was no significant relationship between this quantity and glucose clearance rates (r = 0.18, P greater than 0.1). We conclude that conventionally treated IDDMs are insulin resistant with regard to peripheral glucose uptake.(ABSTRACT TRUNCATED AT 250 WORDS)