Physiological and pathological studies of thermogenic organ, brown adipose tissue

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To evaluate significance of thermogenic organ, brown adipose tissue (BAT), co-operative fresearch has been conducted about the following subjects : 1. cytohistological features of BAT 2. central and peripheral regulatory mechanisms of BAT function 3. pathophysiology of BAT 4. ecology of BAT.Several novel and significant findings have been obtained. Stimulative regulation of BAT through pineal gland was suggested in chinese hamster. Sympathetic noradrenaline was found to increase calucium infux to BAT cell. Neuropeptide Y and substance P fibers in addition to noradrenergic one were abserved to innervate BAT cells as well as vessels. Channels for Cl and K were suggested in inner membrance of BAT mitochondria. Differentiation and proliferation were reproduced in vitro with 3 dimentional collagen-gel culture. Brain-derived lipogenic peptide which stimulated BAT lipogenesis was isolated and purified. Cytokines (IL-1 and TNF) were shown to stimulate BAT thermogenesis through acting on hypothalamic neurons. Action of IL-1 was mediated through CRF.Cold acclimation decreased insulin receptors of BAT, while insulin content increased. Ganglioside GM3 in BAT increased during cold acclimation. Nitric oxide was evidenced to be a messenger molecule for noradrenaline-induced increase in blood flow through BAAT.Deficient BAT thermogenesis was suggeested to be involved in humban obesity. Chemical compositions such as protein and fatty acids in BAT of wild rodents varied according to their diets, ambient temperature and altitude. Proposed objects of this co-operative research is conceded to be nearly attained. Furthermore, it has been recogniaed that BAT is not only concerned with thermorogulatory tghermogenesis in cold acclimation, but energy metabolism and stress response.