Physiological leptin resistance

Abstract

Leptin is an adipose tissue-derived hormone whose circulating levels correlate with the amount of body fat stores. The main function of this adipokine is to regulate energy metabolism. By modulating the expression of orexigenic and anorexigenic neuropeptides in the hypothalamus, leptin reduces appetite. It also increases energy expenditure, contributing to the decrease of body fat and body weight. Mutations in the leptin receptor gene or prolonged consumption of a high-fat diet may impair leptin action, leading to leptin resistance. Resistance to leptin can also be an adaptive response that occurs in seasonal animals and in pregnant mammals. Reversible insensitivity to the satiety signal of leptin promotes hyperphagia, which is essential for animals living in dynamic environments and experiencing seasonal variation in food availability, since it allows them to forage intensely when food is abundant and accumulate fat reserves necessary to survive periods when food is scarce. Moreover, leptin resistance and subsequent hyperphagia develop during pregnancy in order to meet the energy needs of the growing fetus. Physiological leptin resistance may be due to impaired transport of leptin across the blood-brain barrier and/or to decreased sensitivity of the hypothalamus to this hormone resulting from an inhibition of leptin signalling in hypothalamic neurons. In pregnancy, an increased resistance to leptin action is also mediated by the binding of this adipokine to its placenta-derived soluble receptor. Reduced entry of leptin into the brain as well as alterations in the leptin signalling pathway in the hypothalamus leads to a transient decrease in sensitivity to this hormone preventing appetite suppression.

Concentrations of Ghrelin and Leptin in Children with Cystic Fibrosis

“…It is known that the intensity of lipogenesis depends on the status of nourishment, the concentration of glucose and cholesterol in blood serum. In the analysed group of patients, abnormal concentrations of cholesterol and TG were concluded in only 9%, mainly in the form of increased levels of cholesterol [30]. El-Shehaby proved that significantly abnormal (higher) levels of ghrelin in patients with hepatic cirrhosis are related to eating and metabolic disorders; while the concentrations of leptin were relatively lower [28].…”

Seasonal and Nutritional Fluctuations in the mRNA Levels of the Short Form of the Leptin Receptor (LRa) in the Hypothalamus and Anterior Pituitary in Resistin-Treated Sheep

“…In sheep, leptin must be transported by the BBB to activate first-order LRb -expressing neurons that are linked to downstream neurons to ultimately control food intake and energy expenditure [ 15 ]. The hypothalamic regulation of energy homeostasis involves an interconnected neural network that contains specialized neurons located in the ARC, the ventromedial nucleus (VMH), and the dorsomedial nucleus (DMH) [ 16 , 17 ].…”

Analysis of Ghrelin and Leptin Concentrations in Saliva in a Selected Population of Children Aged 10-13 Years in the Silesia Province (Poland)

“…It is one of the main adipocytokine protein hormones that inhibit appetite, hence its name from the Greek leptos, meaning slim [4]. It is secreted mainly by adipose tissue and in small amounts by other organs and tissues, e.g., placenta, brain, stomach, mammary glands and skeletal muscles [5,6]. It circulates in the blood in a free form or bound to plasma proteins.…”