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A Palou

Publications and source records attributed to A Palou.

At least 37 records · Page 2Linked to original sources
PubMed2001

Sex-dependent dietary obesity, induction of UCPs, and leptin expression in rat adipose tissues.

OBJECTIVE: The aim of this study was to determine the sex-dependent differences in the response of key parameters involved in thermogenesis and control of body weight in brown adipose tissue (BAT) and white adipose tissue (WAT) in postcafeteria-fed rats, a model of dietary obesity. RESEARCH METHODS AND PROCEDURES: BAT and WAT were obtained from male and female control and postcafeteria-fed Wistar rats. Postcafeteria-fed rats were initially fed with cafeteria diet from day 10 of life until day 110 (cafeteria period) and with standard chow diet from then until day 180 of life (postcafeteria period). Body mass and energy intake were evaluated. Biometric parameters were analyzed in interscapular BAT (IBAT). Levels of uncoupling protein 1 (UCP1), alpha(2)-adrenergic receptor (AR), and beta(3)-AR proteins and UCP1, UCP2, UCP3, beta(3)-AR, and leptin mRNAs, in IBAT or WAT, were studied by Western blot and Northern blot analyses, respectively. RESULTS: Rats attained 59% (females) and 39% (males) increase in body weight at the end of the cafeteria period. During the postcafeteria period, the rats showed a loss of body weight, which was higher in females. Postcafeteria-fed female rats also presented higher activation of thermogenic parameters in IBAT, including UCP1, UCP2, and UCP3 mRNAs. Female control rats showed lower levels of both alpha 2 and beta(3)-ARs in BAT compared with male rats, but these levels in postcafeteria-fed female and male rats were the same, because males tended to down-regulate them. Levels of leptin mRNA in response to the postcafeteria state depended on gender and the specific WAT depot studied. DISCUSSION: It is suggested that in postcafeteria-fed female rats, BAT thermogenic capacity becomes more efficiently activated than in males. Female rats also showed a bigger weight loss. The parallel regulation of the levels of UCP2 and UCP3 mRNAs, with respect to UCP1 mRNA, with higher activation in female postcafeteria-fed rats, suggests a possible role of both UCP2 and UCP3 in the regulation of energy expenditure and in the control of body weight. The distinct responses to overweight of alpha 2 and beta(3)-ARs--which were sex dependent--and leptin mRNA--which depended on both sex and WAT depot--also support the different response of thermogenesis-related parameters between overweight males and females.

Adipose Tissue↗
PubMed2000

Chromatographic determination of carotenoids in foods.

In recent years, there has been particular emphasis on obtaining more accurate data on the types and concentrations of carotenoids in foods for various health and nutrition activities. The analysis of carotenoids is complicated because of the diversity and the presence of cis-trans isomeric forms of this group of compounds. In addition, a wide variety of food products of vegetal and animal origin, vegetables and animal samples contain carotenoids, and a great range of carotenoids can be found in these samples. The characteristic conjugated double bond system of carotenoids produces the main problem associated with work and manipulation on carotenoids, that is their particular instability, especially towards light, heat, oxygen and acids. For this reason, several precautions are necessary when handling carotenoids. Another problem associated with analysis of carotenoids is the difficulty in obtaining standard compounds. High-performance liquid chromatographic methods for the determination of carotenoids in foods are reviewed. The sample extraction and treatment, carotenoid purification and standard manipulation are briefly commented on. We present a critical assessment of chromatographic methods developed for the determination of carotenoids in foods. Finally, some methods for carotenoid ester separation are reviewed.

Carotenoids↗
PubMed2000

Obesity: molecular bases of a multifactorial problem.

Obesity could well become the most common health problem of the 21st century. There are more opportunities to consume large quantities of food: big portions of tasty, varied food, at reasonable prices, are available everywhere. Moreover, our bodies are better adapted to combat weight loss than to combat weight gain, since for thousands of years our species evolved in circumstances where nutrients were in short supply. The response of each individual to diet and other environmental factors varies considerably, depending on the characteristics of his/her body weight control mechanisms. The differentiating element in the future, especially as regards the dietary and pharmacological control of obesity, will be knowledge of an individual's possible response depending on his/her genetic background. Obesity can occur as a result of genetic or acquired changes in three main types of biochemical processes, which are the main focus of this review: a)feeding control, which determines the sensations of satiety and hunger through processes that depend on an interplay between internal signals (notably leptin) and environmental factors; b) energy efficiency, in particular the activation of thermogenesis mediated by uncoupling proteins (UCPs) that makes it possible to dissipate part of the energy contained in food as heat instead of accumulating it as fat, and c) adipogenesis, the process by which cells specialised in fat storage (adipocytes) are formed, which is controlled by an interplay of transcription factors, including members of the C/EBP, PPARgamma and ADD families. The knowledge of a growing number of genes and molecules implicated in these three types of processes and of their metabolic relationships is leading toward a molecular understanding of the body weight regulatory system, and is paving the way for new methods of obesity control, especially pharmacological but also nutritional and possibly involving genetic intervention.

Adipose Tissue↗
PubMed2000

Methodological approaches to assess body-weight regulation and aetiology of obesity.

Obesity, which is becoming one of the major health hazards in developed and developing societies, results from a long-term positive energy balance. Body-weight regulation and stability depend on an axis with three interrelated components: food intake, energy expenditure and adipogenesis, although there are still many unknown features concerning fuel homeostasis and energy balance. Biochemical processes are interconnected, and a separate consideration of each component is often useful for methodological purposes and to achieve a better understanding of the whole system. Thus, many different experimental approaches can be applied by using laboratory animals, cell culture or human subjects to unravel the molecular mechanisms which participate in body-weight regulation. Thus, both in vitro (cellular and subcellular models) and in vivo methods have dramatically increased our knowledge of weight control. Several strategies in obesity research are reported here, exploiting the opportunities of the molecular era as well as novel whole-body approaches, which will impact on the development of new targets for obesity management and prevention.

Animals↗
PubMed2000

Association of sets of alleles of genes encoding beta3-adrenoreceptor, uncoupling protein 1 and lipoprotein lipase with increased risk of metabolic complications in obesity.

OBJECTIVE: To investigate the relationship between the polymorphisms of the beta3-AR (Trp64Arg), UCP1 (A-->G) and LPL (HindIII and PvuII) loci and the metabolic complications associated with obesity in a Turkish population. SUBJECTS: 271 unrelated individuals of Turkish origin including obese (body mass index, BMI>30 kg¿m2) and lean (BMI< or =25 kg¿m2) subjects. MEASUREMENTS: Anthropometric (weight, height and blood pressure) and metabolic measurements (plasma levels of glucose, cholesterol and triglycerides), and determination of beta3-AR, UCP1 and LPL genotypes by polymerase chain reaction followed by enzymatic digestion. RESULTS: The distributions of genotypes for each candidate gene (beta3-AR, UCP1 and LPL) were similar between the obese and the lean subjects. The Arg64 allele of the beta3-AR gene was absent from massively obese men. GG carriers of the A-->G variant of the UCP1 gene showed BMI-associated increases of cholesterol levels which were more marked than both AA (P=0.027) and AG (P=0.039) carriers. Obese P+ carriers of the LPL PvuII variant had significantly higher levels of glucose than non-carriers (P=0.011), whereas obese P+P+ carriers did not have significantly different levels of triglycerides than non-carriers (P=0.087). Moreover, carriers of both alleles (G&P+) had higher levels of glucose than non-carriers (P=0.048), but did not have significantly different levels of triglycerides than non-carriers (P=0.125). However, the BMI-associated increase of triglycerides of P+&G carriers was significantly more marked than that of P+ carriers (P=0.0085). CONCLUSION: Our data support the idea that alleles of specific genes (UCP1, LPL and beta3-AR) might play a role in the development of certain metabolic complications of obesity and might have additive effects when combined with each other (as in the case of UCP1 and LPL). International Journal of Obesity (2000)24, 93-100

Adult↗
PubMed2000

In vivo effects of CGP-12177 on the expression of leptin and uncoupling protein genes in mouse brown and white adipose tissues.

OBJECTIVE: 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. DESIGN: 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). RESULTS: 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. CONCLUSION: 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.

Adipose Tissue↗
PubMed2000

Secretory granules of endocrine and chief cells of human stomach mucosa contain leptin.

BACKGROUND: Leptin plays an important role in the control of food intake and body weight homeostasis. In humans, leptin is produced by adipocytes, placental cells and secretory cells of the mammary epithelium. Recently, it has been reported that stomach glands produce leptin in rats. OBJECTIVE: To test the expression of leptin protein in human stomach and localize, by immunocytochemistry, the specific cell type producing leptin. DESIGN: Endoscopic stomach biopsies of six patients were used to investigate leptin production in the fundic epithelium using reverse transcription polymerase chain reaction (RT-PCR) of RNA. Leptin protein was detected by immunoblot analysis and localized by immunohistochemistry and ultrastructural immunocytochemistry (immunogold method). RESULTS: Human gastric epithelium expresses leptin mRNA and leptin protein. The cells in the lower half of the stomach glands were immunoreactive for leptin. Ultrastructural immunocytochemistry showed leptin immunoreactivity in the pepsinogen granules of chief cells, but the granules of a specific endocrine cell type in the basal portion of the glands were also positive. CONCLUSIONS: Our results suggest that gastric leptin could function in the short-term system to control feeding behaviour and is probably secreted in the stomach lumen by chief cells and into the stomach circulation by a special type of endocrine cell.

Adult↗
PubMed2000

Effects of cafeteria diet feeding on beta3-adrenoceptor expression and lipolytic activity in white adipose tissue of male and female rats.

OBJECTIVE: To investigate the effects of short term (15 days) cafeteria diet feeding on the expression of beta3-AR in vivo and its association with lipolytic stimulation induced by beta3-AR agonist CGP12177A in isolated white adipocytes. ANIMALS: Six female and 6 male Wistar rats (at 4 weeks of age) were fed on a cafeteria diet plus standard diet for 15 days. The remaining 12 age- and sex-matched rats always received standard diet only. MEASUREMENTS: White gonadal adipose tissue was isolated and used for the determination of beta3-AR and leptin expression, and for in vitro studies of lipolytic activity. RESULTS: Control male rats had higher levels of both beta3-AR and leptin mRNA in white adipose tissue than their female counterparts. Both male and female rats up-regulated the levels of both beta3-AR and leptin mRNA in response to 15 day cafeteria diet feeding. Noradrenaline- and isoprenaline-induced lipolysis were significantly increased in fat cells from control females compared to their male counterparts. CGP12177A stimulation resulted in significantly higher glycerol release in fat cells from cafeteria diet-fed female rats, whereas there were no differences due to dietary treatment in male rats. The maximal lipolytic response of forskolin (stimulating adenylyl cyclase) and dibutyryl cyclic AMP (cyclic AMP analogous) was not affected by sex or cafeteria diet feeding. CONCLUSION: Cafeteria diet feeding brings about higher excess body weight and impaired adipose tissue lipolytic activity in female rats compared to male rats. Thus, the higher levels of beta3-AR mRNA induced by cafeteria feeding are not indicative per se of an increase of the lipolytic response of the adipocytes. The changes seen in other adrenoceptor subtypes (beta1 and beta2) may be more determinant of the overall lipolytic response of adipocytes.

Adipocytes↗
PubMed2000

The activity of cytochrome oxidase is increased in circulating lymphocytes of patients with chronic obstructive pulmonary disease, asthma, and chronic arthritis.

We have previously shown that the activity of cytochrome oxidase (CytOx) in skeletal muscle of patients with chronic obstructive pulmonary disease (COPD) was higher than in healthy control subjects. The mechanisms and implications of this observation were unclear. In particular, it was not known if this abnormality can occur also in: (1) cell types other than muscle cells, and (2) other chronic inflammatory diseases. To obtain further insight into these questions, we measured the activity of CytOx in circulating lymphocytes in patients with stable COPD (n = 17), bronchial asthma (n = 6), or chronic arthritis (n = 5), and in healthy control subjects (n = 8). We found that, compared with healthy subjects (280 +/- 117 nKat/microg protein), patients with COPD showed increased CytOx activity (430 +/- 150 nKat/microg protein, p = 0.01) in lymphocytes. Further, this activity was negatively related to the degree of airflow obstruction present in these patients (r = -0.53, p < 0.05). We also found that the activity of CytOx in circulating lymphocytes was higher than normal in patients with chronic arthritis (411 +/- 130 nKat/microg protein, p < 0.05) and, particularly, in patients with bronchial asthma (1,667 +/- 1,027 nKat/microg protein, p < 0.001). These results show that the increased CytOx activity previously reported in skeletal muscle of patients with COPD is also detected in other cell types (such as circulating lymphocytes) and in other chronic inflammatory diseases (such as bronchial asthma and chronic arthritis). The mechanisms and implications of these findings deserve further investigation.

Arthritis↗
PubMed2000

Opposite effects of feeding a vitamin A-deficient diet and retinoic acid treatment on brown adipose tissue uncoupling protein 1 (UCP1), UCP2 and leptin expression.

The relationship between interscapular brown adipose tissue (IBAT) thermogenic potential and vitamin A status was investigated by studying the effects of feeding a vitamin A-deficient diet and all-trans retinoic acid (tRA) treatment on body weight and IBAT parameters in mice. Feeding a vitamin A-deficient diet tended to trigger opposite effects to those of tRA treatment, namely increased body weight, IBAT weight, adiposity and leptin mRNA expression, and reduced IBAT thermogenic potential in terms of uncoupling protein 1 (UCP1) mRNA and UCP2 mRNA expression. The results emphasize the importance of retinoids as physiological regulators of brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1999

Brown adipose tissue response to cafeteria diet-feeding involves induction of the UCP2 gene and is impaired in female rats as compared to males.

Noradrenaline-dependent brown adipose tissue (BAT) thermogenesis is activated by the cold and excess energy intake, largely depends on the activity of the uncoupling protein 1 (UCP1), and is mediated mainly through the beta3-adrenoceptor (beta3-AR). We investigated the expression of ucp2, a gene that encodes a putative UCP1-like uncoupling protein, along with that of ucp1 and beta3-ar, in the interscapular BAT (IBAT) of male and female rats chronically fed a cafeteria diet. After 3 months on this diet, male rats attained a 34% excess body mass and showed IBAT hypertrophy and increased IBAT thermogenic potential, in terms of both UCP1 and UCP2 mRNA expression (both by 1.6-fold), UCP1 protein expression (by 1.75-fold) and GDP binding to IBAT mitochondria (by 2.2-fold); female rats attained a larger excess body weight (50%) and their IBAT, although hypertrophied, showed no signs of increased thermogenic potential per gram of tissue. Interestingly, the IBAT of female rats was already activated compared to males. Treatment of mouse brown adipocytes in primary culture with noradrenaline also triggered a dose-dependent increase of the levels of UCP1 mRNA and UCP2 mRNA. Retroregulatory down-regulation of the beta3-AR mRNA levels was found in the two models used. The results support a physiological role for UCP2, along with UCP1, in rodent BAT thermogenesis.

Adipose Tissue, Brown↗
PubMed1999

Effects of fasting on lipoprotein lipase activity in different depots of white and brown adipose tissues in diet-induced overweight rats.

The aim of the present study was to evaluate the effects of 24 hours of starvation on lipoprotein lipase (LPL) activity in various depots of white and brown adipose tissues in control rats and in rats with two different degrees of overweight, both induced by dietary treatment. In control rats, no changes in LPL immunoreactive mass were observed in either white or brown adipose tissues after fasting, whereas the effects of food deprivation on enzyme activity were opposite in white versus brown adipose tissues. The LPL activity response to fasting was impaired by obesity: White adipose depots of cafeteria obese rats showed a lower ability to downregulate LPL during fasting and the increased LPL activity induced by fasting in brown adipose depots was less intense in the obese rats compared with control animals. When the degree of overweight was reduced, the differences between obese and control rats were also attenuated.

Journal Article↗
PubMed1999

Stimulation of uncoupling protein 1 expression in brown adipocytes by naturally occurring carotenoids.

OBJECTIVE: To assess the effect of naturally occurring carotenoids on brown adipocyte proliferation and differentiation. The rationale behind is that certain carotenoids have provitamin A activity in mammals, and that one of the active forms of vitamin A, (retinoic acid) is known to behave as a transcriptional activator of the key gene for brown fat thermogenesis, the one encoding the uncoupling protein thermogenin (UCP1). DESIGN: Confluent primary cultures of mice brown adipocytes were treated with various concentrations of carotenoids. Cell morphology, total culture protein content, the DNA synthesis rate, and the levels of UCP1, retinoic acid receptor alpha (RARalpha) and retinoid X receptor alpha (RXRalpha) were analysed. RESULTS: Treatment with beta-carotene, alpha-carotene and lutein promoted UCP1 expression in a dose-dependent manner, with an effectiveness that was related to their potency as vitamin A precursors. Cell morphology, total culture protein content at confluence and DNA synthesis rate were unaffected after carotenoid treatment up to 10 microM. CONCLUSION: The results indicate that carotenoids can positively affect the expression of UCP1 without altering brown adipocyte proliferation.

Adipocytes↗
PubMed1999

Glucose erythrocyte transporter in women with breast cancer: changes in lipid composition of erythrocyte membrane.

Women with breast cancer show altered blood glucose compartmentation compared with healthy women, with lower concentrations in plasma and similar concentrations in blood cells. The goal of this paper was to study whether this pattern was the result of changes in the erythrocyte glucose transporter and, if so, to assess the possible changes in lipid environment of the erythrocyte membrane. In 12 women with different degrees of breast cancer and 12 age-matched healthy women, the lipid composition of erythrocyte membrane and erythrocyte glucose transport were studied. Women with breast cancer showed changes in both the kinetic variables and the lipid environment of the glucose transporter, in keeping with an increase in fluidity of the erythrocyte membrane. The results obtained would account, in part, for the changes in glucose compartmentation.

Aged↗
PubMed1999

Sex differences in the effect of obesity on human plasma tryptophan/large neutral amino acid ratio.

BACKGROUND: The neurotransmitter serotonin (5-HT) contributes to the regulation of food intake and appetite behavior, and its rate of synthesis depends upon brain tryptophan (TRP) availability in relation to the large neutral amino acids (LNAAs). Thus, the ratio of TRP to the sum of LNAA (TRP/LNAA) will be representative of the 5-HT brain levels. Differences between men and women in the obesity-linked alterations in whole blood amino acid levels and compartmentation have been described. The aim of this work was to study the effect of obesity on brain TRP availability in men and women and to determine whether there are sex-linked differences. METHODS: The plasma levels of TRP and LNAAs in 42 men and 46 women (classified according to their body mass index (BMI) into lean, overweight and obese) have been determined by HPLC. RESULTS: The TRP/LNAA ratio shows a significant drop which is even more pronounced in men than in women as BMI increases. Moreover, the comparison of the values between the 3 BMI groups revealed that the drop in the TRP/LNAA ratio appears with overweight in men but only with obesity in women. CONCLUSION: These sex differences could affect hypothetical behavioral differences of feeling hunger when facing voluntary food restriction for weight loss in individuals of different genders and with varying degrees of obesity.

Amino Acids↗
PubMed1998

Stimulation of uncoupling protein synthesis in white adipose tissue of mice treated with the beta 3-adrenergic agonist CGP-12177.

The effects of chronic treatment with the beta 3-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.

Adipose Tissue↗
PubMed1998

Sex-associated differences in cold-induced UCP1 synthesis in rodent brown adipose tissue.

The effects of acute and chronic acclimation to cold on uncoupling protein 1 (UCP1) levels, as well as on GDP-binding to mitochondria, cytochrome c oxidase activity and mitochondrial protein concentration in brown adipose tissue (BAT) of intact male and female rats have been analyzed. Results reveal that females rats are more sensitive to cold because their threshold temperature for the thermogenic response is set at a higher value (around 22 degreesC) than that of males (around 18 degreesC), hence leading to differences in BAT UCP1 levels between the sexes at different environmental temperatures. In vitro experiments showed that steroid hormones, beta-estradiol, estrone and progesterone, can reduce norepinephrine-induced UCP1 synthesis in brown adipocytes differentiated in primary culture. Thus the different sex-associated response of cold-induced thermogenesis in rats does not appear to be explained by a direct action of sex steroids upon the adipocyte, implying that other factors in the thermogenic regulatory system must be involved.

Adipose Tissue, Brown↗