Thyrotropin-releasing hormone levels under water-immersion stress in rats

Abstract

We studied changes in the concentrations of the immunoreactive thyrotropin-releasing hormone (IR-TRH) in the hypothalamus, stomach and gastric juice under water-immersion stress in rats. Male Sprague-Dawley rats, restrained in water for 0.5, 1, 2, 4, 6 and 8 hours, were decapitated and the IR-TRH concentrations in the tissues and gastric juice were measured by a specific radioimmunoassay.
The ulcer index of the rat stomach became higher, as the time of water-immersion stres became longer. The IR-TRH concentrations in the hypothalamus of rats restrained for 0.5, 1 and 2 hours were significantly lower than pre-stress levels. However, IR-TRH concentrations in the hypothalamus of rats stressed for 4 to 8 hours returned to normal levels. In the rat adenostomach, the concentrations of IR-TRH were significantly lower in the all restrained groups, whereas IR-TRH concentrations in gastric juice were significantly higher after 1 hour or more water immersion stress. These findings suggest that TRH is released from hypothalamus in the central nervous system (CNS) and from gastric tissue to gastric juice in the stomach under water-immersion stress in rats.
We suggest that TRH may be related to the pathogenesis of stress ulcers in the CNS and stomach.