Effects of HPA hormones on adapted lymphocyte responsiveness to repeated stress.
Acute stress-induced immune alterations can result in adapted function with prolonged exposure to the same stressor. The present study was designed to evaluate the possible role of the hypothalamic-pituitary-adrenocortical (HPA) axis on the adaptation of spleen lymphocyte responsiveness to repeated stress. For this purpose, we selected a stressful protocol (aversive auditory stimulation) that induced an initial suppression (1 day), followed by a return to control values with repeated application (4 days), of mitogen-induced lymphocyte proliferation. Because rats exposed to 4 days of noise sessions show enhanced adrenocorticotropin (ACTH) and corticosterone levels, we tested the possibility that adaptation of lymphoproliferation by repeated stress was due to a desensitization of splenic lymphocytes to stress-released HPA hormones. The results showed that corticotropin-releasing factor (10(-9) M) and corticosterone (5 x 10(-8) and 10(-7) M), as well as dexamethasone (10(-8), 5 x 10(-8), and 10(-7) M), significantly suppressed lymphoproliferation from both control and stressed rats in a similar way. ACTH (10(-9) and 5 x 10(-9) M) did not significantly influence Concanavalin-A-stimulated spleen lymphocytes. These data indicate that adaptation of lymphocyte proliferation by repeated noise stress occurs without accompanying alterations in lymphocyte responsiveness to HPA hormones.
Sandi
C
C
Psychobiology Research Group, Cajal Institute, CSIC, Madrid, Spain.
Cambronero
J C
JC
Borrell
J
J
Guaza
C
C
D000161:Acoustic Stimulation; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008214:Lymphocytes / Q000276:immunology / Q000502:physiology*; D008297:Male; D008934:Mitogens / Q000494:pharmacology; D010913:Pituitary-Adrenal System / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000166:cytology / Q000187:drug effects; D013315:Stress, Psychological / Q000503:physiopathology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
D008934:Mitogens; D003208:Concanavalin A; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone