Adiponectin is one of the most clinically relevant cytokines associated with obesity. However, circadian rhythmicity of adiponectin in human adipose tissue (AT) has not been analyzed. To assess whether the mRNA levels of adiponectin and its receptors (ADIPOR1 and ADIPOR2) might show daily circadian rhythms in visceral and sc fat explants obtained from morbid obese women, visceral and sc abdominal AT biopsies (n = 6) were obtained from morbidly obese women (body mass index >or=40 kg/m(2)). Anthropometric variables were measured and fasting plasma glucose, lipid, and lipoprotein concentrations were analyzed. To investigate rhythmic expression pattern, AT explants were cultured during 24 h, and gene expression was analyzed at the following times: 0800, 1400, 2000, and 0200 h, using quantitative real-time PCR. All genes investigated showed a circadian rhythmicity and oscillated accurately and independently of the suprachiasmatic nucleus in both AT explants (P < 0.05). Adiponectin gene expression fluctuated in the same phase as its receptors. Correlation analyses between the genetic circadian oscillation and components of the metabolic syndrome revealed that adiposity and abdominal obesity correlated with a decrease in adiponectin and adiponectin receptors ADIPOR1 and ADIPOR2 amplitude (P < 0.05). Visceral fat showed a trend toward a phase delay and dampening of the mRNA amplitude of adiponectin as compared with sc fat. The mRNA expression of adiponectin and its receptors showed 24-h rhythmicity in human AT from morbidly obese patients.
"In agreement with our hypothesis, we have demonstrated in humans the circadian rhythmicity of the CLOCK expression in both subcutaneous and visceral adipose tissue in culture conditions. This is consistent with previous observations for BMAL1, PER2 and other clock genes (CRY1) , cortisol-related genes  and some adipokines ,  using similar experimental approaches. Moreover, in the present study the significant P-values obtained by periodic regression analysis in both adipose tissue depots show that CLOCK, BMAL1 and PER2 expression adjusts to a typical 24 h sinusoidal curve (see Table 1 and Figure 1). "
[Show abstract][Hide abstract] ABSTRACT: to examine firstly whether CLOCK exhibits a circadian expression in human visceral (V) and subcutaneous (S) adipose tissue (AT) in vitro as compared with BMAL1 and PER2, and secondly to investigate the possible effect of the glucocorticoid analogue dexamethasone (DEX) on positive and negative clock genes expression.
VAT and SAT biopsies were obtained from morbid obese women (body mass index≥40 kg/m(2)) (n = 6). In order to investigate rhythmic expression pattern of clock genes and the effect of DEX on CLOCK, PER2 and BMAL1 expression, control AT (without DEX) and AT explants treated with DEX (2 hours) were cultured during 24 h and gene expression was analyzed at the following times: 10:00 h, 14:00 h, 18:00 h, 22:00 h, 02:00 h and 06:00 h, using qRT-PCR.
CLOCK, BMAL1 and PER2 expression exhibited circadian patterns in both VAT and SAT explants that were adjusted to a typical 24 h sinusoidal curve. PER2 expression (negative element) was in antiphase with respect to CLOCK and in phase with BMAL1 expression (both positive elements) in the SAT (situation not present in VAT). A marked effect of DEX exposure on both positive and negative clock genes expression patterns was observed. Indeed, DEX treatment modified the rhythmicity pattern towards altered patterns with a period lower than 24 hours in all genes and in both tissues.
24 h patterns in CLOCK and BMAL1 (positive clock elements) and PER2 (negative element) mRNA levels were observed in human adipose explants. These patterns were altered by dexamethasone exposure.
PLoS ONE 12/2012; 7(12):e50435. DOI:10.1371/journal.pone.0050435 · 3.23 Impact Factor
"A number of adipocyte-specific factors have also shown rhythmic expression. Some examples are leptin, adipsin, resistin, and adiponectin (Garaulet & Madrid, 2009; Gomez-Abellan et al., 2010). On the other hand, studies have shown sleep restriction to decrease glucose tolerance and compromise insulin sensitivity (Padilha et al., 2010; Taheri et al., 2004). "
[Show abstract][Hide abstract] ABSTRACT: The authors examined the associations of shiftwork with overweight and abdominal obesity through a cross-sectional study of 1206 employees 18 to 50 yrs of age who were working on a production line in a poultry processing plant. Night-shift workers (n = 800) were considered exposed, whereas day shiftworkers (n = 406) were considered nonexposed. Overweight was defined as a body mass index ≥ 25 kg/m(2) and abdominal obesity as a waist circumference ≥ 88 cm in women and ≥ 102 cm in men. The mean age of the workers was 30.5 yrs (standard deviation = 8.7 yrs), and 65.2% were women. Nightshift workers compared to dayshift workers showed higher prevalences of overweight (42.2% vs. 34.3%; p= .020) and abdominal obesity (24.9% vs. 19.5%; p = .037). After adjusting for sociodemographics, parental overweight status, behavioral characteristics, and sleep characteristics, including hours of sleep, the prevalence ratios for overweight and abdominal obesity were 1.27 (95% confidence interval [ CI]: 1.00-1.61) and 1.45 (95% CI: 1.10-1.92), respectively, for the nightshift workers compared to the dayshift workers. A consistent finding in our study was the independent contribution of night shiftwork to overweight and abdominal obesity among Brazilian workers. Further studies are needed to understand the biological mechanisms involved and the complex behavioral and social adaptations experienced by night-shift workers.
Chronobiology International 04/2012; 29(3):336-43. DOI:10.3109/07420528.2011.653851 · 3.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Circadian rhythmicity has been widely studied in the cardiovascular system and has a relevant role in three different areas:
heart, vascular smooth muscle, and hemostatic capacity of blood. Metabolic syndrome (MetS) and chronodisruption are also highly
interconnected. Epidemiologic studies show that shift workers and short sleepers develop obesity and MetS impairments more
frequently. In addition, studies performed in experimental models suggest that the circadian clock genes network plays an
important role in mammalian energy balance and demonstrate the implication of the clock genes machinery in MetS. New nutrigenomic
studies indicate that genetic variants of the CLOCK gene are highly associated with cardiovascular risk and MetS features. The timing of antihypertensive therapies should be
also considered to achieve a nocturnal dip in the pattern of blood pressure. Chronotherapy could also be used in MetS treatment,
as the appropriate resetting of the circadian system (ie, “chronoenhancement”) may lead to a reduced incidence of obesity
Current Cardiovascular Risk Reports 01/2010; 4(1):15-23. DOI:10.1007/s12170-009-0074-z
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.