COLD-INDUCED SALT INTAKE IN MICE AND CATECHOLAMINE, RENIN AND THERMOGENESIS MECHANISMS

Cold induces increased intake of salt in mice. To examine involvement of renin and catecholamines, male ICR mice were exposed to cold (7-9 d egrees C; 6h/day; 4 days), and half of them were allowed to choose bet ween water and 0.9% NaCl. Plasma renin activity (PRA) and catecholamin e concentrations in plasma, adrenal gland, kidney, brown adipose tissu e (BAT) and brain were examined in three phases: for 9 h before exposu re to cold, during 6 h of cold exposure and for 9 h after the exposure . The amount of salt intake from NaCl solution and from food, PRA and noradrenaline (NE) concentrations in kidney and medulla oblongata were higher during cold and the 9 h after exposure to cold than during the 9 h before the exposure. These results are consistent with the sugges tion that cold-induced catecholamine metabolism enhanced activity in t he renin-angiotensin system, which played an important role in the aro usal of salt appetite. During cold exposure, concentrations of NE and dopamine in BAT were higher in mice with access to NaCl solution than those without NaCl to drink. These results suggest that cold-induced s alt intake enhanced non-shivering thermogenesis, and are consistent wi th our previous report that high salt intake helped to maintain coloni c temperature under cold exposure. (C) 1996 Academic Press Limited