Comparable effects of adrenalectomy and C fiber depletion on delayed-type hypersensitivity in rats.
OBJECTIVE
To determine the influence of the hypothalamic-pituitary-adrenal (HPA) axis and sensory C fibers on cell-mediated immunity, the time course of allergic contact dermatitis (ACD) was examined in normal, adrenalectomized (ADX) and capsaicin (CAP)-treated rats.


METHODS
Five days after sensitization with 2,4-dinitro-1-fluorobenzene (DNFB) onto the back, rats were challenged with DNFB on the pinna. ADX or CAP treatment was performed a week before the sensitization.


RESULTS
Ear swelling in normal rats reached a peak 24 h after the challenge and subsided gradually to about half of this peak 72 h afterwards. Plasma ACTH levels increased about 9 times more than those of nonsensitized rats 72 h after the challenge. ADX rats, in which the plasma corticosterone level was significantly lower than that in sham-operated animals, exhibited more rapid development of ACD, which reached a peak 12 h after the challenge. However, the swelling returned to about half of the maximum within 48 h. In CAP-treated rats, ACD reached a peak 6 h after the challenge and recovered quickly as in ADX rats. Plasma ACTH levels in CAP- treated rats were significantly lower than those in vehicle-treated rats.


CONCLUSIONS
The rapid development of and recovery from ACD in ADX and CAP-treated rats, both of which showed suppression of the HPA axis, indicated a biphasic action of the HPA axis on ACD, i.e. inhibitory in the early phase but augmentative in the late phase of ACD.
Katafuchi
T
T
Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. kataf@physiol.med.kyushu-u.ac.jp
Kondo
T
T
Hori
T
T
D000315:Adrenalectomy; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D017449:Dermatitis, Allergic Contact / Q000276:immunology / Q000378:metabolism; D004139:Dinitrofluorobenzene / Q000494:pharmacology; D006968:Hypersensitivity, Delayed / Q000139:chemically induced / Q000276:immunology* / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000276:immunology*; D007111:Immunity, Cellular / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000276:immunology*; D015213:Neuroimmunomodulation / Q000187:drug effects / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar
D000324:Adrenocorticotropic Hormone; D004139:Dinitrofluorobenzene; D002211:Capsaicin