Activation of rat pituitary-adrenocortical and sympatho-adrenomedullary system in response to different stressors.
OBJECTIVE
The effects of three different long-term (21 days) stresses: isolation(LTI), forced swimming (LTS) and isolation accompanied by forced swimming (LTI+LTS) on the level of plasma noradrenaline (NA), adrenaline (A), corticosterone (CORT) and adrenocorticotropic hormone (ACTH), both under basal conditions and in response to short-term immobilization and cold as heterotypic additional stressors, were compared.


METHODS
Plasma NA and A were assayed by the radioenzymatic method. Plasma CORT was measured using RIA kits. Plasma ACTH was determined by chemiluminescent method.


RESULTS
LTI produced a significant elevation of basal plasma CORT and ACTH, while basal plasma NA and A concentrations remained unchanged. Combination of long-term isolation and forced swimming, produced a significant elevation of basal plasma ACTH content only, while LTS did not influence the basal level of this hormone. When LTI rats were exposed to immobilization and cold, a significant elevation of plasma NA and A level was recorded. In LTS and LTI+LTS groups of rats exposed to immobilization or cold, increased plasma NA and A levels were observed, but this increase was lower in comparison with that found in LTI rats. No difference in plasma CORT content between the three long-term stressed groups of animals was observed, while plasma ACTH level was significantly more elevated in LTS and LTI+LTS than in LTI rats.


CONCLUSIONS
Based on these results, it may be concluded that LTI as a psychosocial stress represents a stronger stressor than LTS. Also, daily short-term (15 min, 21 days) swimming stress seems to attenuate the effect of long-term isolation on the activity of sympatho-adrenomedullary system.
Gavrilovic
Ljubica
L
Institute of Nuclear of Sciences Vinca, Laboratory of Molecular Biology and Endocrinology, 11000 Belgrade, Serbia and Montenegro.
Dronjak
Sladjana
S
D000313:Adrenal Medulla / Q000503:physiopathology*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003080:Cold Temperature; D003345:Corticosterone / Q000097:blood; D004837:Epinephrine / Q000097:blood; D049449:Luminescence; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010913:Pituitary-Adrenal System / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D012934:Social Isolation; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming / Q000523:psychology; D013564:Sympathetic Nervous System / Q000503:physiopathology*
D000324:Adrenocorticotropic Hormone; D003345:Corticosterone; D009638:Norepinephrine; D004837:Epinephrine