[Psychoendocrinological studies on the pituitary-adrenocortical system in rats. part 1: Relationship between emotional stress (novel stimulus) and plasma corticosterone (author's transl)].
The effect of emotional stress on the pituitary-adrenocortical system in the rat was studied. Hall's open field apparatus was used to give a novel stimulus, a mild and purely not show any significant differences among all the experimental groups. Psychological stimulus produced by a novel environment. Animals were male albino rats of the Wistar-strain, bred in groups and weighing about 250 gm. They were taken out of their home cage and placed gently in the centre of an open field, a novel environment. After a certain period of time, they were returned to the cage and decapitated. Plasma corticosterone was determined by the fluorometric method of van der Vies. The results were as follows: 1. When the animals were exposed to the novel stimulus for 3 min., plasma corticosterone showed a definite increase 15 min. after the end of the stimulus, reached a maximal level at 30 min. and returned to the resting level at 60 min. 2. When the duration of the stimulus, i.e. time spent in the open field, was changed, a 15min.-stay in the field gave the maximal rise of plasma corticosterone and 30, 45, 60min.-stays maintained the plateau level. When the 3 min. open field test was repeated every day, the plasma coritcosterone response was definite in the first trial, but was suppressed at the second and absent at the third and fifth episodes. The results indicate that the acquisition of adaptation to a novel stimulus depends upon the repetition, but not upon the duration of stimulus. 3. Plasma corticosterone responded in the same manner as in the standard open field test, even when olfactory, visual and special factor were changed. This indicates that no special cue (s) is responsible for the adrenocortical response to a novel stimulus. 4. The pretreatment of the animals with tranquilizers such as chloropromazine and diazepam showed no inhibitory effect on the plasma corticosterone response to novel stimulus.
D000818:Animals; D002746:Chlorpromazine / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood*; D003975:Diazepam / Q000494:pharmacology; D006801:Humans; D008297:Male; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013315:Stress, Psychological / Q000187:drug effects / Q000502:physiology*
D003975:Diazepam; D002746:Chlorpromazine; D003345:Corticosterone