Temporal and substrate-dependent patterns of stress protein expression in the hypothalamus of caloric restricted rats.

Stress proteins (sps) 27, 34, 70 and 90 (Mr x 10(3)) were induced in the hypothalamus of caloric restricted (CR) rats by feeding stress. A definite time pattern for sps synthesis was observed when their induction was examined at several time points after the rats were fed, and the level of sps expression was found to vary significantly at different times of the day. The same group of proteins was induced in ad libitum fed rats when they were subjected to food deprivation for 48 h. Stress protein 34 expression in the hypothalamus of old caloric restricted rats was found to be dependent on blood glucose levels, and was substantially reduced when insulin was added to the glucose infusion. The expression of sps 27, 70 and 90, however, was little changed with glucose and/or insulin infusion.