(2019) report that, paradoxically, reducing leptin levels in obese mice increases their sensitivity to the concentrations that remain, and leads to reductions in weight gain, thus suggesting why these earlier trials may have failed and possibly a new approach to treating obesity.
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.
Obesity in cloned mice is likely to reflect epigenetic abnormalities that arise partly from inadequate nuclear programming; these obese mice display a unique phenotype that is suggestive of a defect other than malfunction of the leptin-melanocortin system, which occurs in most rodent models of obesity and in human obesity.
Obesity increases the expression of leptin and other cytokines, as well as some macrophage and inflammatory markers, and decreases adiponectin expression in adipose tissue.A number of cytokines, e.g. tumour necrosis factor alpha (TNF-alpha) and monocyte chemotactic protein 1 (MCP-1), and some pro-inflammatory interleukins, leuckocyte antigens, chemochines, surface adhesion molecules and metalloproteases are up-regulated whereas other factors are down-regulated.
Obesity is a well-established risk factor for endometrial cancer, due in part to the adipokines generated by adipose tissue, such as adiponectin (also known as Acrp30) and leptin, which are associated with many endocrine-related cancers.
Obesity is linked with an increased cancer risk and studies have also revealed that leptin may be involved in breast tumorigenesis particularly among obese women.
Obesity is a strong risk factor for the development of cardiovascular diseases and is associated with a marked increase in circulating leptin concentration.
Obesity induced an increase of inducible nitric oxide synthase (iNOS)-expressing macrophages and neutrophils which peaked at 48 h after the last OVA challenge, and was associated with higher levels of interleukin (IL)-4, IL-9, IL-17A, leptin and interferon (IFN)-γ in the lungs.
Obesity as measured by body mass index (BMI) is associated with risk of several cancers and has also been suggested as a risk factor for CM, and may also be related to insufficient 25(OH)D and/or high leptin levels.
Obesity and the metabolic syndrome (MS) are characterized by an increase in circulating leptin concentrations, in parallel to a decrease in blood levels of adiponectin.
Obesity is a risk factor for PC that could affect 5-FU effectiveness through the adipokine leptin, which is a known proliferation, survival factor and Notch inducer.