The different expression patterns of genes for uncoupling proteins (UCPs) 1, 2 and 3 (ucp1, ucp2 and ucp3) were studied in interscapular brown adipose tissue (BAT) and in four white adipose tissue ...(WAT) depots (epididymal, inguinal, mesenteric and retroperitoneal) in male rats of different ages (18 days-12 months). UCP mRNA expression levels were determined by Northern blotting. In BAT, there were high levels of expression of UCP1 and UCP3 mRNA, but no detectable levels of UCP2 mRNA. Both ucp1 and ucp3 followed a similar expression pattern with age, with high levels in suckling rats which decreased to 50% or less in rats just under 2 months old, declining thereafter until 5 months and then recovering with age. However, an additional peak of expression was observed for ucp3 at the age of 3 months. In WAT, ucp1 expression was rare: occasional expression was found for UCP1 mRNA in the retroperitoneal depot in suckling rats and in the epididymal and inguinal depots in suckling and mature adult rats. ucp2 and ucp3 had different developmental expression patterns, but these were similar for each gene in the different depots studied. UCP3 mRNA was highly expressed in rats soon after birth, it decreased until 3 months, and increased thereafter, except for the mesenteric WAT where ucp3 expression decreased until 7 months before recovering. The fact that changes with age of both ucp1 and ucp3 expression have a similar profile in BAT, which is also similar to the ucp3 and also ucp1 profiles in some WAT depots, might reflect a common regulatory pattern for the expression of these genes, and also a common function. In contrast to ucp1 and ucp3, ucp2 had a peak of expression at about 2 months, and lower expression at 3 months, suggesting different regulation and probably a different role for this UCP.
Beta-carotene (BC) was found to enhance lung cancer risk in smokers. This adverse effect was unexpected because BC was thought to act as an anti-oxidant against cigarette smoke-derived radicals. ...These radicals can directly or indirectly damage DNA, leading to the formation of pro-mutagenic DNA lesions such as 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) and 3-(2-deoxy-β-D-erythro-pentafuranosyl)pyrimido1,2-αpurin-10(3H)-one deoxyguanosine (M1dG). Later, it was suggested that high concentrations of BC could also result in pro-oxidant effects. Therefore, we investigated whether high but physiologically feasible concentrations of BC were able to alter (i) the formation of radicals in vitro assessed by electron spin resonance spectroscopy, (ii) the levels of 8-oxo-dG and M1dG in vitro in lung epithelial cells after incubation with hydrogen peroxide (H2O2) and the smoke-derived carcinogen benzoapyrene (BaP) and (iii) the levels of 8-oxo-dG and M1dG in vivo in ferrets’ lung after chronic exposure to BaP. BC increased in vitro hydroxyl radical formation in the Fenton reaction but inhibited the formation of carbon-centered radicals. Similarly, BC was able to enhance 8-oxo-dG in vitro in lung epithelial cells. On the other hand, BC significantly inhibited M1dG formation in lung epithelial cells, especially after induction of M1dG by H2O2 or BaP. Finally, BC supplementation of ferrets also resulted in a significant decrease in M1dG, but in contrast to the in vitro experiments, no effect was observed on 8-oxo-dG levels, probably because of increased base excision repair capacities as assessed by a modified comet assay. These data indicate that the fate of BC being a pro- or anti-oxidant strongly depends on the type of radical involved.
Context:
The melanocortin-4 receptor gene (MC4R) plays a pivotal role in the regulation of body fat and food and energy intake.
Objectives:
The objectives of the study were as follows: 1) to evaluate ...the association of variants rs17782313 and rs17700633 near the coding region of MC4R and 2) to evaluate the association of the transcript levels of MC4R with adiposity indices and percentage of energy from fat, carbohydrates, and protein in children.
Design:
The Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants (IDEFICS) cohort was used, with examinations at baseline (T0) and after 2 years (T1).
Setting and Participants:
A total of 16 228 schoolchildren (2–9 y) from eight European countries participated in the study. A random sample of 4381 children genotyped for MC4R variants and a subsample of 410 children with MC4R expression data in peripheral blood cells (PBCs) were included in the analyses.
Main Outcome Measures:
Anthropometric measures and energy intake (total and from fat, carbohydrates, and protein) served as outcomes for adiposity status and for dietary behavior, respectively.
Results:
At T0, the C allele of rs17782313 (minor frequency allele 23%) was significantly associated with higher values of adiposity indices (all P < .001). No association was found between rs17700633 (minor frequency allele 28%) and the variables under study. At T1, the C allele of rs17782313 was associated with a significantly higher increase in the adiposity indices over time (all P < .05). The MC4R expression levels in PBCs were inversely associated with body fat and energy intake from carbohydrates and directly with energy from fat (all P ≤ .05) but were not influenced by variants rs17782313 and rs17700633.
Conclusions:
The common variant rs17782313 near MC4R was cross-sectionally and longitudinally associated with body mass index and measures of body fatness in children aged 2–9 years. We showed, for the first time in humans, that MC4R expression levels in PBCs are related to body fat distribution and percentage of energy intake from carbohydrates and fat.
We showed for the first time that both MC4R variant rs17782313 and MC4R expression in peripheral blood cells are associated with adiposity in children. MC4R expression is also associated with energy intake from carbohydrates and fat.
To assess the effect of chronic treatment with CGP-12177 a beta3-adrenergic receptor (AR) agonist with beta2/beta1-AR antagonist action, on the expression of the leptin gene and of genes coding for ...uncoupling proteins (ucp1, ucp2 and ucp3) in brown and white adipose tissues.
NMRI mice received a daily subcutaneous injection of CGP-12177 at a dose of 0.05, 0.2, 0.5 or 1 mg/kg for 15 days. The specific levels of the mRNAs of interest were analysed in interscapular brown adipose tissue (BAT) and in two white adipose tissue (WAT) depots, inguinal (IWAT) and epididymal (EWAT).
No changes in food intake or body weight were detected at any dose of CGP-12177. In the two WAT depots, the treatment led to enhanced expression of ucp1 and ucp3, but not of ucp2. In BAT, low doses (0.05 and 0.2 mg/kg) led to a decreased expression of the three ucp genes, whereas a slight stimulatory effect on the three ucp genes was elicited with a high dose (1 mg/kg). Treated animals displayed increased expression of leptin in BAT and, to a lesser extent, in IWAT, but not in EWAT.
The results reveal that simultaneous stimulation of the expression of certain ucp genes and the leptin gene can be achieved, and suggest that adrenergic regulation of the leptin gene and of genes of the ucp family in adipose tissues is the result of complex interactions between the different beta-AR pathways.
The effects of chronic treatment with the β3- adrenergic receptor agonist CGP-12177 on uncoupling protein (UCP) synthesis in interscapular brown adipose tissue (IBAT), various white fat depots and ...skeletal muscle have been examined in the mouse (daily injection for 15 days at a dose of 0.5 mg/kg). The treatment increased the IBAT UCP content and led to the expression of UCP in inguinal white adipose tissue. The increase in IBAT UCP content took place in the absence of tissue hypertrophy, and despite the increase in total body UCP content, no changes in body weight were observed after the treatment. The results confirm that ectopic expression of UCP in non-BAT tissues can be induced after chronic adrenergic stimulation.
We aimed to assess the potential effects of hesperidin and capsaicin, independently and in combination, to prevent the development of obesity and its related metabolic alterations in rats fed an ...obesogenic diet. Three-month-old male Wistar rats were divided into 5 groups: Control (animals fed a standard diet), WD (animals fed a high fat/sucrose (western) diet), HESP (animals fed a western diet + hesperidin (100 mg/kg/day)), CAP (animals fed a western diet + capsaicin (4 mg/kg/day)), and HESP + CAP (animals fed a western diet + hesperidin (100 mg/kg/day) + capsaicin (4 mg/kg/day)). Hesperidin and capsaicin were administered by gavage. Capsaicin decreased body fat gain and prevented insulin resistance, whereas hesperidin showed little effect on body fat gain and no apparent effects on insulin resistance. No additive effects were observed with the combination. Capsaicin and hesperidin, separately, improved blood lipid profile, diminished hepatic lipid accumulation, and prevented non-alcoholic steatohepatitis in western diet-fed rats, but the combination showed lower effects. Hesperidin alone, and to a lesser extent capsaicin or the combination, displayed hypotensive effects in western diet-fed rats. In conclusion, capsaicin and hesperidin, separately, exhibit health beneficial effects on metabolic syndrome-related alterations in western diet-fed rats, but the effects are mitigated with the combination.
We explored the potential of hesperidin and capsaicin, separately and in combination, to induce white adipose tissue (WAT) browning and to help body weight management in Western diet-fed rats. Adult ...male Wistar rats were fed for 8 weeks with Western diet and treated daily with hesperidin (100 mg/kg/day), capsaicin (4 mg/kg/day), hesperidin (100 mg/kg/day) + capsaicin (4 mg/kg/day), or the vehicle. Hesperidin and capsaicin separately, but not (or to a lesser extent) the combination, resulted in a decreased size of adipocytes and induced emergence of multilocular brown-like adipocytes positive for UCP1 and CIDEA in retroperitoneal WAT. Expression levels of browning markers, such as Prdm16, in inguinal WAT also increased with capsaicin treatment compared with the vehicle (145% ± 17% vs 92% ± 21%, P < 0.05), but no significant effects were found with the combination (106% ± 12%). Thus, the combination of both bioactives reduces the effectiveness of each compound to decrease the adipocyte size and induce WAT browning.
Given the co-existence of the three β-adrenoceptor (βAR) subtypes (
β
1AR,
β
2AR and
β
3AR) in brown adipocytes, the present study was undertaken to determine the relative importance of these in the ...induction of UCP synthesis in mouse BAT precursor cells in primary culture. Cells at different stages of differentiation were exposed to different β AR agonists: prenalterol (a selective
β
1AR agonist), salbutamol or clenbuterol (selective
β
2AR agonists), or BRL 37344 (a selective
β
3AR agonist). As with the endogenous agonist, noradrenaline, and the non-selective β AR agonist, isoprenaline, all four β AR agonists induced UCP in the confluent stage of the cells, but with different potencies, and with the highest induction being seen after clenbuterol or BRL 37344 treatment. Cells in the confluent stage of development were the most sensitive to the effects of the agonists, although clenbuterol and BRL 37344 induced a weak UCP synthesis in pre-confluent cells. None of these β AR agonists were able to induce UCP synthesis in the post-confluent period. The responses to prenalterol and salbutamol were inhibited by propranolol at relatively low concentrations, suggesting their effects were mediated by
β
1AR and
β
2AR, respectively. However, propranolol was a particularly weak antagonist of BRL 37344 and, unexpectedly, of the clenbuterol UCP responses, which suggests that both induce UCP synthesis via the
β
3AR. In summary, the
β
3AR is the most important adrenoceptor coupled to the induction of UCP synthesis, although both
β
1AR and
β
2AR activation may make a contribution. However, all three β AR subtypes do not become fully functional until cultured cells become confluent.
The stability of the mRNA coding for the uncoupling protein thermogenin was investigated in mouse brown-fat cells differentiated in culture. After 7 days in culture, the cells were stimulated for 24 ...h with noradrenaline, and a high level of thermogenin mRNA was then observed. If noradrenaline treatment was continued, the mRNA level remained high, but, upon withdrawal of noradrenaline, the level decreased rapidly, with a half-life of only 2.7 h. The presence of transcriptional (actinomycin) or translational (cycloheximide) inhibitors prolonged the apparent half-life by about 50%. The presence of noradrenaline during transcriptional blockade led to a further stabilization of thermogenin mRNA. It was concluded that an induced (or short-lived) gene product is important for thermogenin mRNA degradation. Direct interaction of noradrenaline with the cultured brown adipocytes could apparently not mimic the paradoxical destabilization of thermogenin mRNA in vivo, previously observed in the cold-exposed mouse Jacobsson, Cannon and Nedergaard (1987) FEBS Lett. 244, 353-356, indicating significant differences between the systems in vitro and in vivo.
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