Aging and glial responses to lipopolysaccharide in vitro: greater induction of IL-1 and IL-6, but smaller induction of neurotoxicity.
Glial activation during aging was analyzed in primary glia cultured from brain regions sampled across the life span. An initial study showed that phenotypes of activated astrocytes and microglia from aging rat cerebral cortex persisted in primary cultures (Neurobiol. Aging 19 (1998), 97). We extend these findings by examining effects of age on the activation of glial cultures from adult rat brain in response to lipopolysaccharide (LPS), an inflammatory stimulus. Mixed glia from F344 male rats, aged 3 and 24 months, cultured from cerebral cortex (Cx), hippocampus (Hc), and striatum (St), were assayed for cytokines implicated in Alzheimer's disease: IL-1alpha, IL-1beta, IL-6, and TNF-alpha. Regional differences across all age groups included consistently lower expression of these cytokines in glia derived from Cx than Hc and St. Aging increased basal IL-6 mRNA and secretion by >or=3-fold in glia from Cx and Hc. Aging also increased LPS-induced IL-1 and IL-6 in Hc more than in Cx, whereas no significant effects of age were seen in St-derived glial cytokines. TNF-alpha secretion did not differ by donor age (basal or LPS-induced). Nitric oxide production by microglia from Cx of aging brains showed a smaller induction in response to LPS, with proportionately less neurotoxicity. Thus, glial activation during aging shows regional selectivity in cytokine expression, with opposite effects of aging on the increased inducibility of IL-1 and IL-6 vs the decreased production of nitric oxide.
Xie
Zhong
Z
Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0191, USA.
Morgan
Todd E
TE
Rozovsky
Irina
I
Finch
Caleb E
CE
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D018920:Coculture Techniques; D003342:Corpus Striatum / Q000166:cytology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006624:Hippocampus / Q000166:cytology; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology; D009569:Nitric Oxide / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide