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Skeletal muscles and bone tissue form the musculoskeletal apparatus, a complex system essential for the voluntary movement. The loss of muscle mass and muscle strength is often associated with a loss of bone mass, in a "hazardous duet" which implies the co-existence of sarcopenia-osteoporosis and exposes patients to a deterioration in quality of life and increased mortality. From the mechanostat theory to the recent definition of the osteosarcopenia syndrome, many aspects of muscle-bone interaction have been investigated in recent decades. The mechanical interaction is now accepted, considering the close anatomical relationship between the two tissues, however, much remains to be discovered regarding the biochemical muscle-bone interaction. Skeletal muscle has been defined as an endocrine organ capable of exerting an action on other tissues. Myokines, bioactive polypeptides released by the muscle, could represent the encrypted message in the communication between muscle and bone. These two tissues have a reciprocal influence on their metabolisms and respond in a similar way to the multiple external factors. The aim of this review is to stimulate the understanding of the encrypted language between muscle and bone, highlighting the role of catabolic pathways and oxidative stress in the musculoskeletal apparatus to elucidate the shared mechanisms and the similarity of response to the same stimuli by different tissues. Our understanding of muscle-bone interactions it could be useful to identify and develop new strategies to treat musculoskeletal diseases, together with pharmacological, nutritional and exercise-based approaches, which are already in use for the treatment of these pathologies., (Copyright © 2021. Published by Elsevier Ltd.)

Cholesterol homeostasis is a highly regulated process in human body because of its several functions underlying the biology of cell membranes, the synthesis of all steroid hormones and bile acids and the need of trafficking lipids destined to cell metabolism. In particular, it has been recognized that peripheral and central nervous system cholesterol metabolism are separated by the blood brain barrier and are regulated independently; indeed, peripherally, it depends on the balance between dietary intake and hepatic synthesis on one hand and its degradation on the other, whereas in central nervous system it is synthetized de novo to ensure brain physiology. In view of this complex metabolism and its relevant functions in mammalian, impaired levels of cholesterol can induce severe cellular dysfunction leading to metabolic, cardiovascular and neurodegenerative diseases. The aim of this review is to clarify the role of cholesterol homeostasis in health and disease highlighting new intriguing aspects of the cross talk between its central and peripheral metabolism., (Copyright © 2020. Published by Elsevier Ltd.)