Visceral fat accumulation is associated with circadian blood pressure in Japanese patients with impaired glucose tolerance

Relationships between computed tomography-assessed density, abdominal fat volume, and glucose metabolism after sleeve gastrectomy in Japanese patients with obesity

In this study, we investigated the relationships between body weight (BW), computed tomography (CT)-assessed abdominal adipose tissue, and the glycemic metabolic profile in obese Japanese patients following laparoscopic sleeve gastrectomy (LSG). This study analyzed adipose tissue compartments using CT methods before and 1 year after LSG. Thirty obese patients were studied, and variables measured included visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), density of VAT (VAT-D), and density of SAT (SAT-D). We also examined the parameters in patients according to whether they had type-2 diabetes (T2DM). LSG induced significant losses in BW, SAT, and VAT after LSG. Additionally, SAT-D and VAT-D both increased and fasting plasma glucose (FPG) and HbA1c, but not C-peptide, decreased after surgery. ΔSAT and ΔVAT were positively related, and ΔSAT-D and ΔVAT-D were negatively related to ΔBW and/or FPG. Furthermore, a multivariate regression model showed that total BW loss (TBWL) was closely related to ΔSAT (β = 0.84; p < 0.001) and ΔVAT-D (β = -0.45; p < 0.05) and improvement of FPG was related to ΔVAT (β = 0.61; p < 0.05) after LSG. Finally, ΔFPG was correlated with ΔVAT in 16 T2DM patients (r = 0.58; p < 0.05) but not in non-T2DM patients. TBWL was related to ΔSAT and ΔVAT-D, and improvement of FPG was related to ΔVAT in obese Japanese patients after LSG.

Blood pressure rhythmicity and visceral fat in children with hypertension

Primary hypertension is associated with disturbed activity of the sympathetic nervous system and altered blood pressure rhythmicity. We analyzed changes in cardiovascular rhythmicity and its relation with target organ damage during 12 months of antihypertensive treatment in 50 boys with hypertension (median, 15.0 years). The following parameters were obtained before and after 12 months of antihypertensive treatment: 24-hour ambulatory blood pressure, left ventricular mass, carotid intima-media thickness, and MRI for visceral and subcutaneous adipose tissue. Amplitudes and acrophases of mean arterial pressure and heart rate rhythms were obtained for 24-, 12-, and 8-hour periods. After 1 year of treatment, 68% of patients were normotensive, and left ventricular mass and carotid intima-media thickness decreased in 60% and 62% of patients, respectively. Blood pressure and heart rate rhythmicity patterns did not change. Changes in blood pressure amplitude correlated with the decrease of waist circumference (P=0.035). Moreover, the decrease of visceral fat correlated with the decrease of 24-hour mean arterial pressure and heart rate acrophases (both P<0.05). There were no differences in changes of blood pressure and heart rate rhythms between patients who achieved or did not achieve normotension and regression of left ventricular mass and carotid intima-media thickness. It was concluded that abnormal cardiovascular rhythmicity persists in children with primary hypertension despite effective antihypertensive treatment, which suggests that it may be the primary abnormality. The correlation between changes in cardiovascular rhythmicity and visceral obesity may indicate that the visceral fat plays an important role in the sympathetic activity of adolescents with hypertension.

Circadian rhythms in adipose tissue: an update

PURPOSE OF REVIEW

Over the past decade, evidence has accumulated from basic science, clinical and epidemiological studies linking circadian mechanisms to adipose tissue biology and its related comorbidities, diabetes, metabolic syndrome and obesity. This review highlights recent in-vitro and in-vivo findings from murine, human and model organism studies.

RECENT FINDINGS

High-fat diets attenuate circadian mechanisms in murine adipose depots and these effects appear to be due to obesity rather than hyperglycemia. Deletion of circadian regulatory genes such as AMPK1 and nocturnin alter the circadian biology of adipose tissue. Unlike the mouse, circadian gene oscillation in human adipose tissue appears to be independent of BMI and diabetes status, suggesting that circadian mechanistic variation occurs across species. Clues for future directions in this emerging field come from studies of the hibernation and torpor state in mammals and infection models involving the Drosophila metabolic organ or 'fat body'.

SUMMARY

There is a growing consensus that circadian rhythms and metabolism are tightly regulated in adipose tissue and peripheral metabolic organs. Although central mechanisms are critical, autonomous clocks exist within the adipocytes themselves. Future circadian advances are likely to result from the studies of adipose tissue-specific gene deletions.