Age-related regional difference of interleukin-1 expression in rat brain after lipopolysaccharide treatment

Aging is associated with altered immune responses including dysregulation o f cytokine production. Of cytokines, interleukin-1 (IL-1) family has been p rimarily involved with central nervous system. To evaluate the age-related different response of IL-1 family following peripheral administration of li popolysaccharide (LPS), immunohistochemical study of Il-1 beta and IL-1 rec eptor expression was performed on Sprague-Dawley rat brain. Experimental an imals were divided into four groups; saline-treated young (3-5 months) and old (over 24 months), and LPS-treated young and old groups. After intraperi toneal (i.p.) injection of LPS, three to five rats within each group were k illed at 1, 2, 4, 8 and 16 hr. After fixation in 4% neutral buffered formal in, the brain slices were paraffin-embedded. Immunohistochemical staining u sing labelled streptavidin biotin was performed. The results showed that IL -1 beta immunoreactivity was seen in the endothelial cell of pens in both L PS-treated young and old rats, with slightly longer persistency in old grou p. IL-1RI immunoreactivity appeared initially in the neurons of cerebral co rtex in LPS-treated old group, compared with predominantly the cerebellum i n LPS-treated young group. in conclusion, our study shows that there is age -related, different neuronal localization of IL-1RI expression at different points of time after LPS treatment.