Associations between circulating free fatty acids, visceral adipose tissue accumulation, and insulin sensitivity in postmenopausal women

Tadalafil Improves Haemodynamics and Arterial Stiffness but Not Flow- Mediated Dilation in Grade 1 Obesity. A Single-dose, Placebo-controlled Clinical Trial

OBJECTIVE

Obesity, a major health issue worldwide, is associated with increased cardiovascular risk, endothelial dysfunction, and arterial stiffness. Tadalafil has been demonstrated to improve vascular parameters.

AIM

To evaluate the effect of a single 20 mg dose of tadalafil on flow-mediated dilation and hemodynamic and arterial stiffness markers.

METHODS

A randomized, double-blind, placebo-controlled study was conducted on 80 participants (41 assigned to placebo and 39 to tadalafil) with grade 1 obesity, to evaluate the acute effect of a single dose of 20 mg of tadalafil on flow-mediated dilation and hemodynamic and arterial stiffness markers.

RESULTS

Tadalafil did not modify flow-mediated dilation. However, it significantly lowered systolic blood pressure (SBP) (130.6±17.1 vs. 125.0±12.7 mmHg, p=0.011), diastolic blood pressure (82.7±18.2 vs. 76.5±11.8 mmHg, p≤0.001), central systolic blood pressure (116.33±19.16 vs. 109.90±15.05 mmHg, p=0.001), the augmentation index (69.1±17.1 vs. 65.7±14.4, p=0.012), and brachial-ankle pulse wave velocity (1229.7±218.4 vs. 1164.0±181.7, p=0.001).

CONCLUSION

A single dose of tadalafil did not modify flow-mediated dilation in patients with grade 1 obesity but improved blood pressure and brachial-ankle pulse wave velocity.

Bidirectional communication between brain and visceral white adipose tissue: Its potential impact on Alzheimer's disease

A variety of axes between brain and abdominal organs have been reported, but the interaction between brain and visceral white adipose tissue (vWAT) remains unclear. In this review, we summarized human studies on the association between brain and vWAT, and generalized their interaction and the underlying mechanisms according to animal and cell experiments. On that basis, we come up with the concept of the brain-vWAT axis (BVA). Furthermore, we analyzed the potential mechanisms of involvement of BVA in the pathogenesis of Alzheimer's disease (AD), including vWAT-derived fatty acids, immunological properties of vWAT, vWAT-derived retinoic acid and vWAT-regulated insulin resistance. The proposal of BVA may expand our understanding to some extent of how the vWAT impacts on brain health and diseases, and provide a novel approach to study the pathogenesis and treatment strategies of neurodegenerative disorders.

Suppression of IGF binding protein-3 by palmitate promotes hepatic inflammatory responses

IGF-binding protein-3 (IGFBP-3) is a liver-derived, anti-inflammatory molecule that is decreased in obesity, a key risk factor for nonalcoholic fatty liver disease (NAFLD). It was not known whether IGFBP-3 levels were altered in NAFLD, whether such alterations could be the result of lipotoxicity, and whether altered IGFBP-3 could affect pathways that are involved in hepatic and systemic inflammation. Serum IGFBP-3 was decreased in patients with NAFLD, whereas liver and circulating IL-8 levels were increased. Palmitate inhibited IGFBP-3 secretion by THP-1 macrophages and enhanced IL-8 expression. Exposure of palmitate-treated THP-1 macrophages to IGFBP-3-deficient conditioned medium led to a 20-fold increase in palmitate-induced IL-8 expression by hepatocytes. Conversely, overexpression of IGFBP-3 suppressed JNK and NF-κB activation and blocked palmitate-induced IL-8 expression in hepatocytes. Silencing IGFBP-3 in Huh7 cells enhanced JNK and NF-κB activity and increased palmitate-induced IL-8 secretion. These data indicate that IGFBP-3 serves as an anti-inflammatory brake in hepatocytes against JNK and NF-κB and limits their activation and downstream production of proinflammatory cytokines. Under lipotoxic conditions, palmitate inhibits hepatic macrophage secretion of IGFBP-3, thereby releasing the brake and enhancing palmitate-induced IL-8 synthesis and secretion.-Min, H.-K., Maruyama, H., Jang, B. K., Shimada, M., Mirshahi, F., Ren, S., Oh, Y., Puri, P., Sanyal, A. J. Suppression of IGF binding protein-3 by palmitate promotes hepatic inflammatory responses.

Dissecting adipose tissue lipolysis: molecular regulation and implications for metabolic disease

Lipolysis is the process by which triglycerides (TGs) are hydrolyzed to free fatty acids (FFAs) and glycerol. In adipocytes, this is achieved by sequential action of adipose TG lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase. The activity in the lipolytic pathway is tightly regulated by hormonal and nutritional factors. Under conditions of negative energy balance such as fasting and exercise, stimulation of lipolysis results in a profound increase in FFA release from adipose tissue (AT). This response is crucial in order to provide the organism with a sufficient supply of substrate for oxidative metabolism. However, failure to efficiently suppress lipolysis when FFA demands are low can have serious metabolic consequences and is believed to be a key mechanism in the development of type 2 diabetes in obesity. As the discovery of ATGL in 2004, substantial progress has been made in the delineation of the remarkable complexity of the regulatory network controlling adipocyte lipolysis. Notably, regulatory mechanisms have been identified on multiple levels of the lipolytic pathway, including gene transcription and translation, post-translational modifications, intracellular localization, protein-protein interactions, and protein stability/degradation. Here, we provide an overview of the recent advances in the field of AT lipolysis with particular focus on the molecular regulation of the two main lipases, ATGL and HSL, and the intracellular and extracellular signals affecting their activity.

Effects of endurance exercise training on risk components for metabolic syndrome, interleukin-6, and the exercise capacity of postmenopausal women

We conducted this study to investigate how an exercise program affects the risk components of metabolic syndrome (MS), serum interleukin (IL)-6 levels, and exercise capacity in postmenopausal women. A randomized clinical trial design was used. Women in an exercise group participated in a treadmill-exercise program for 12 weeks, whereas women in a control group maintained their customary lifestyle. Data on variables were collected at baseline and after 12 weeks of the study, which was completed by 46 women (mean age, 56.0 ± 7.0 y). Our results indicate endurance exercise exerted significant beneficial effects on waist circumference, serum high-density lipoprotein cholesterol (HDL-C) and IL-6 levels, and exercise capacity (all P < 0.05). The beneficial effects on IL-6 and exercise capacity were correlated with improvements in HDL-C levels (r = -0.33, P = 0.03 and r = 0.31, P = 0.04, respectively). Our results suggest that health-care providers can incorporate an exercise program in treatments to improve the health of postmenopausal women.

Glucose tolerance of premenopausal women after menopause due to surgical removal of ovaries

OBJECTIVE

To evaluate the influence of the abrupt withdrawal of ovarian function on glucose tolerance by studying premenopausal women before and after oophorectomy.

METHODS

Thirty premenopausal women who needed hysterectomy for benign reasons volunteered for the study in our hospital in Istanbul, Turkey. An oral glucose tolerance test (OGTT) was performed before surgery and 3, 6 and 12 months after surgery. Fasting glucose, fasting insulin levels and insulin/glucose indexes, HOMA indexes, insulin and glucose levels were measured during OGTT.

RESULTS

The mean fasting and 2-h glucose levels of the women did not change significantly during the 12 months of follow-up. However, the glucose levels during the glucose tolerance tests changed significantly after surgery (p<0.05). Insulin responses to the glucose tolerance test also increased significantly (p<0.005). Insulin/glucose indexes were significantly higher after surgery (p<0.005). Type 2 diabetes mellitus was detected in five women and impaired glucose tolerance was detected in 12 of the 30 patients after surgery in the 12-month period.

CONCLUSION

The impairment of carbohydrate metabolism due to an abrupt decrease in natural estrogen levels should be considered before removing the ovaries during hysterectomy in premenopausal patients.