Changes in levels of parameters related to lifestyle diseases in rats as results of heat selection for generations.

We have been selected rats by heat for many generations and developed an inbred FOK rat. The FOK rats resist heat using long-lasting saliva spreading despite severe dehydration. In addition, FOK rats congenitally resist to cold by increase in oxygen consumption. . In the present study, changes in levels of parameters related to lifestyle diseases were studied in the FOK rat. FOK rats were mildly fat than the other strains. Size of visceral fat was larger than those in other strains. Plasma triglyceride level was lower than those in the other strains. It was partially recovered by β-adrenergic blocker. Phospholipids level was higher than those in the other strains. Therefore, major component of plasma lipid in FOK rats was phospholipids. Polyunsaturated fatty acids, DHA and arachidonic acid, in plasma phospholipids were higher than those in the other strains. The FOK rat was one of strains which responded with large psychological stress-induced fever. Microarray analysis showed a possibility that gene expressions of AIM-1, aldosterone receptor and iron-responsive element -binding protein were increased in the hypothalamus in FOK rats. These increase in gene expression suggested a possible changes in osmoregulation, lipid metabolism, brain-Na induced hypertension, sympathetic outflow, and oxidative stress, especially genotoxic stress, in FOK rats. These findings suggested that heat selection for generations changes values of parameters related to lifestyle diseases. [Jpn J Physiol 54 Suppl:S235 (2004)]