Influence of adrenal demedullation on stress-related behaviour in Wistar rats.

The influence of adrenal demedullation on stress-related behaviour (chronic immobilization) was investigated in respect to the following parameters and physiological processes: number of animals surviving the exposure, blood pressure behaviour, endogenous opioid system, pain sensitivity, endogenous level of substance P (SP) in pituitary and hypothalamus. The results showed that chronic immobilization stress and adrenal demedullation induce the same direction of alterations of physiological processes and parameters. This fact suggests the involvement of common regulatory mechanisms both in demedullation and chronic stress. An important process in this respect may be the induction of functional insufficiency of the adrenal medulla especially concerning the adrenal peptidergic mechanisms. Contrary to the sham operated rats the demedullated animals showed differences in their stress-related behaviour of parameters of adaptive regulatory processes. In rats with demedullation either no additional stress-related alterations of parameters in relation to the general adaptation processes were induced or the demedullation-induced alterations were antagonized partially or completely by chronic immobilization.