Neuropeptide Y immunoreactivity in the spleen and thymus of normal rats and following adjuvant-induced arthritis.

Abstract Immunoreactive neuropeptide Y (irNPY) was detected by radioimmunoassay within the rat thymus and spleen. Total spleen and thymus irNPY contents in control animals were 77 ± 3 ng and 23 ± 1 ng respectively (means ± S.E.M., n = 10). Total tissue contents of irNPY 14 days following bilateral adrenalectomy or induction of inflammatory arthritis were not significantly altered compared to controls. Most spleen irNPY coeluted with synthetic NPY after reversed-phase high-performance liquid chromatography, but two peaks of irNPY were detected in thymic extracts. This suggests that NPY may be differentially expressed in tissues of the immune system.