LDH Assessment of Differential Early Stress in Rats

A study was performed to determine the effects of differential early stress immobilization upon the LDH response in rats. Ninety-six hooded rats 48 of each sex were used as subjects. Three groups of subjects were stressed at ages 6-8, 24-26, and 38-40 days. These three groups were also stressed again at 120 days of age. Three more groups of animals were stressed at identical ages during early development, but not stressed later in life. One group was not stressed early but stressed later in life, and the last group was not stressed at all. The results of the LDH analyses showed that the earlier stress is induced in the rat, the greater is the protective effect of this initial stress, when the animal is exposed again to a stress in adulthood. Specifically, this protective effect was found to occur in the cardiac tissues, and to a smaller extent in hepatic tissues and-or skeletal muscles. No sex differences with regard to LDH-isoenzyme response to stress at different periods of development were found but age-specific differences between males and females, thought to be due to the female hormonal system, were found for LDH-1 and to some extent for LDH-4 and LDH-5.