Leptin: Interactions in Bone Metabolism and Pleiotropic Effects

The osteoblasts and the adipocytes share a common progenitor cell so there is a relationship between the bone and the adipose tissue. The differentiation between the adipocytes and the osteoblasts is regulated by extracellular signaling, coordination of many receptors, and by a series of nuclear interactions. The adipose tissue produces the adipokines that affect the activity of many organs. Leptin (LEP), in particular, can influence bone metabolism, acting on both the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The effects are not yet fully defined. The Body Mass Index (BMI) affects bone density: as a result, low body weight is considered a risk factor involved in osteoporosis fractures with variable effects for the different skeletal sites. Leptin has an anabolic and anti-resorptive role on the bone but also a catabolic effect through the CNS. This hormone is able to influence bone metabolism indirectly through its influence on body weight and sex hormones. LEP is a basic hormone in the maintenance of functional balance not only in the osteoarticular system but in the entire organism acting as a messenger of the information concerning the long-time energy reserves indispensable for the most adequate responses to the maintenance of organic homeostasis. Physical exercise can be useful in the rehabilitation of sarcopenic obesity, linked to hyperleptinemia. In this review, we liked to highlight the many aspects exerted by leptin, so as to also covered some gaps found in other reviews. In addition, we also examined aspects of leptin activity other than bone, as the second purpose of this paper which is also evident from the title: pleiotropic effects.

Automated summary

Osteoblasts and adipocytes share a common progenitor cell and are regulated by extracellular signaling and nuclear interactions. Adipose tissue produces adipokines, such as leptin, which can influence bone metabolism and affect the activity of various organs. Body Mass Index (BMI) affects bone density, and low body weight is considered a risk factor for osteoporosis fractures. Leptin has both anabolic and catabolic effects on bone through its influence on body weight and sex hormones.