Leptin

Publication Title: 
Mechanisms of Ageing and Development

Organisms have evolved neuroendocrine and metabolic response systems to enhance survival during periods of food shortage, which occur frequently in nature. The anti-aging effect of caloric restriction (CR) might derive from these adaptive responses to maximize organism survival. The present article discusses the potential role for leptin, a hormone secreted from adipocytes, as a key signal that induces the adaptive responses relevant to CR.

Author(s): 
Shimokawa, I.
Higami, Y.
Publication Title: 
Current Opinion in Drug Discovery & Development

TOR (target of rapamycin) is a serine-threonine protein kinase that is conserved across a diverse range of species from fungi to mammals. The signaling pathway that is anchored by TOR is also conserved across species. In mammals, mTOR integrates growth factor, amino acid, nutrient and energy sensing signals, and thus plays a major role in cell growth and proliferation, protein synthesis and autophagy.

Author(s): 
Sudarsanam, Sucha
Johnson, Dale E.
Publication Title: 
Minerva Endocrinologica

Adipose tissue is an active metabolic organ secreting adipocytokines which are involved in the energy homeostasis and regulation of glucose and lipid metabolism. Aging is associated with fat redistribution, which is characterized by loss of peripheral subcutaneous fat and accumulation of visceral fat. Visceral adipose tissue is more involved in the developement of metabolic diseases than subcutaneous adipose tissue. Aging also alters the function, proliferation, size, and number of adipose cells which leads to alterations in the secretion, synthesis and function of the adipocytokines.

Author(s): 
Gulcelik, N. E.
Halil, M.
Ariogul, S.
Usman, A.
Publication Title: 
Clinical Interventions in Aging

Obesity is a global epidemic associated with aging-like cellular processes; in both aging and obesity, resistance to hormones such as insulin and leptin can be observed. Leptin is a circulating hormone/cytokine with central and peripheral effects that is released mainly by subcutaneous white adipose tissue. Centrally, leptin controls food intake, energy expenditure, and fat distribution, whereas it controls (among several others) insulin sensitivity, free fatty acids (FFAs) oxidation, and lipolysis in the periphery.

Author(s): 
Carter, Sophie
Caron, Alexandre
Richard, Denis
Picard, FrÈdÈric
Publication Title: 
The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences

One of the most robust observations in the biology of aging is that caloric restriction (CR) extends life in a variety of species. Although CR results in a severalfold decrease in fat mass (FM), the role of fat on life extension was considered to be minimal. Two main reasons accounted for this belief. First, although increased FM is associated with changes in substrate oxidation and in glucose homeostasis, in part through the effects of free fatty acids (FFA) and glycerol, several studies have suggested that longevity is determined independent of FM.

Author(s): 
Barzilai, N.
Gupta, G.
Publication Title: 
The Journal of Nutrition, Health & Aging

Evolutional theories of aging and caloric restriction (CR) in animals predict the presence of neuroendocrine signals to divert the limited energy resources from energy-costly physiologic processes such as reproduction to those essential for survival in response to food shortage. The diversion of energy and subsequent molecular mechanisms might extend the lifespan. A growing body of evidence indicates that leptin, a peptide hormone secreted from adipocytes, has a key role in neuroendocrine adaptation against life-threatening stress such as fasting.

Author(s): 
Shimokawa, I.
Higami, Y.
Publication Title: 
Microscopy Research and Technique

Many hormonal signals from peripheral tissues contribute to the regulation of energy homeostasis and food intake. These regulators including leptin, insulin, and ghrelin, modulate the orexigenic and anorexigenic neuropeptide expression in hypothalamic nuclei. The anti-aging effects of caloric restriction have been explained from an evolutional viewpoint of the adaptive response of the neuroendocrine and metabolic response systems to maximize survival during periods of food shortage.

Author(s): 
Chiba, Takuya
Yamaza, Haruyoshi
Higami, Yoshikazu
Shimokawa, Isao
Publication Title: 
Science (New York, N.Y.)
Author(s): 
Marx, Jean
Publication Title: 
The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences

Insulin-like growth factor (IGF)-1 signaling might partly mediate effects of caloric restriction (CR), an experimental intervention for increasing longevity in mammals. The present study evaluated effects of recombinant human (rh)IGF-1 infusion on adipokine levels in CR and transgenic (Tg) dwarf rats with the reduced growth hormone-IGF-1 axis, which shared similar body weight and food intake. At 9 months of age, each rat received a continuous infusion of rhIGF-1 for 14 days, and rats received an injection of glucose after overnight fasting.

Author(s): 
Yamaza, Haruyoshi
Komatsu, Toshimitsu
To, Kazuo
Toyama, Hiroaki
Chiba, Takuya
Higami, Yoshikazu
Shimokawa, Isao
Publication Title: 
Biogerontology

Adipose tissue plays a pivotal role in ageing and longevity; many studies, both human and animal, have focussed on the effects of food limitation. Here we present a new model based on striking differences between two 'normal' inbred strains of albino Wistar rats the Charles River (CR) and Harlan Olac (HO) that have marked differences in age-related accumulation of fat and insulin-stimulated rates of glucose incorporation into lipid in the epididymal fat pads (EFP).

Author(s): 
Kunjara, Sirilaksana
Greenbaum, A. Leslie
Rademacher, Thomas W.
McLean, Patricia

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