Abstract
The occurrence of the endogenous receptor antagonist for the cytokine interleukin-1 in the rat adrenal gland was analyzed by polymerase chain reaction and by immunohistochemistry using a rabbit polyclonal antiserum. Expression of interleukin-1 receptor antagonist mRNA was demonstrated in both adrenal medulla and cortex, and a marked increase in the transcription was observed after systemic administration of lipopolysaccharides. Interleukin-1 receptor antagonist immunoreactivity was seen in the adrenal medulla, and the immunofluorescence intensity was stronger in the adrenergic, phenylethanolamine N-methyltransferase-positive cells than in the noradrenergic chromaffin cells. The distribution of interleukin-1 receptor antagonist protein is complementary to that of interleukin-1α-like immunoreactivity found in phenylethanolamine N-methyltransferase-negative cells and overlaps with and resembles the distribution of interleukin-1β-immunoreactive material. The expression of the interleukin-1 receptor antagonist in the adrenal gland complements previous findings of large constitutive pools of interleukin-1α and interleukin-1β in this neuroendocrine organ and also suggests participation of adrenal interleukin-1 receptor antagonist in neuroimmune modulation.
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