Biorhythms of activities of liver and blood dehydrogenases and changes in body weight of the rats feeding normal diet or excess of sugar substitutes

Biorhythms with higher levels of activity of sorbitol dehydrogenase and lactate dehydrogenase in blood plasma, specific activity of sorbitol dehydrogenase, lactate dehydrogenase, and malate dehydrogenase in the liver, and body weight of rats were more pronounced in the spring-summer period than in the autumn-winter period. These specific features were revealed in animals feeding a normal diet or food with 54 and 27% sugar substitute sorbitol. However, specific activity of glucose-6-phosphate dehydrogenase in the liver was higher in the autumn-winter period. Activity of sorbitol dehydrogenase in blood plasma increased by tens of times due to induction of sorbitol synthesis (substrate) in the liver. Sugar substitute xylitol is structurally similar to sorbitol, but is not the substrate for sorbitol dehydrogenase. However, the effect of xylitol on activities of lactate dehydrogenase, malate dehydrogenase, and glucose-6-phosphate dehydrogenase in the spring-summer period was similar to that of sorbitol. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 12, pp. 686–689, December, 2007