Sucrose feeding stimulates basal metabolism & nonshivering thermogenesis in undernourished rats

Undernutrition in rats for 60 days from the first day of birth resulted in a significant diminution of nonshivering thermogenesis (NST) and basal metabolic rate (BMR; 12.5 and 5% respectively) as compared to their controls, even when expressed on a metabolic body weight basis. Sucrose (8%) feeding for 72 h of such undernourished (UN) rats immediately after 60 days reverted the depressed NST capacity to levels comparable to control values while the BMR was higher by about 9 per cent than controls. The actual increase in NST and BMR of UN rats after 72 h of sucrose feeding was about 12 and 14 per cent respectively when compared to the values before sucrose feeding. This is possibly because sucrose feeding is known to elevate the caloric intake by 20-30 per cent over normal and would stimulate the sympathetic nervous system (SNS) activity. The results thus would imply that the reduced NST and BMR in rats consequent to undernutrition is probably due to diminished SNS activity which may be associated with changes in some hormonal and brown adipose tissue functions. However, such changes appear to be limited only to the period of undernutrition as it can be corrected speedily by adequate energy supplementation.