title: Voluntary exercise protects hippocampal neurons from trimethyltin injury: possible role of interleukin-6 to modulate tumor necrosis factor receptor-mediated neurotoxicity.
abstract: In the periphery, exercise induces interleukin (IL)-6 to downregulate tumor necrosis factor (TNF), elevate interleukin-1 receptor antagonist (IL-1RA), decreasing inflammation. Exercise also offers neuroprotection and facilitates brain repair. IL-6 production in the hippocampus following exercise suggests the potential of a similar protective role as in the periphery to down-regulate TNFα and inflammation. Using a chemical-induced model of hippocampal dentate granule cell death (trimethyltin, TMT 2.4 mg/kg, ip) dependent upon TNF receptor signaling, we demonstrate neuroprotection in mice with 2 weeks access to running wheel. Exercise attenuated neuronal death and diminished elevations in TNFα, TNF receptor 1, myeloid differentiation primary response gene (MyD) 88, transforming growth factor β, chemokine (C-C motif) ligand 2 (CCL2), and CCL3. Elevated mRNA levels for IL-1α, IL-1RA, occurred with injury and protection. mRNA and protein levels of IL-6 and neuronal expression of IL-6 receptor α, were elevated with injury and protection. Microarray pathway analysis supported an up-regulation of TNFα cell death signaling pathways with TMT and inhibition by exercise. IL-6 pathway recruitment occurred in both conditions. IL-6 downstream signal events differed in the level of STAT3 activation. Exercise did not increase mRNA levels of brain derived neurotrophic factor, nerve growth factor, or glial derived neurotrophic factor. In IL-6 deficient mice, exercise did not attenuate TMT-induced tremor and a diminished level of neuroprotection was observed. These data suggest a contributory role for IL-6 induced by exercise for neuroprotection in the CNS similar to that seen in the periphery.
authors: Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, United States.
authors: Jason A
authors: JA
authors: Funk
authors: Julia
authors: J
authors: Gohlke
authors: Andrew D
authors: AD
authors: Kraft
authors: Christopher A
authors: CA
authors: McPherson
authors: Jennifer B
authors: JB
authors: Collins
authors: G
authors: G
authors: Jean Harry
mesh_terms: D000818:Animals; D018925:Chemokines / Q000096:biosynthesis / Q000235:genetics; D004830:Epilepsy, Tonic-Clonic / Q000139:chemically induced; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015850:Interleukin-6 / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008959:Models, Neurological; D053594:Myeloid Differentiation Factor 88 / Q000096:biosynthesis / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009498:Neurotoxins / Q000633:toxicity*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011828:Radiation Chimera; D011897:Random Allocation; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000187:drug effects* / Q000502:physiology; D013047:Specific Pathogen-Free Organisms; D014202:Tremor / Q000139:chemically induced; D014298:Trimethyltin Compounds / Q000633:toxicity*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology; D015854:Up-Regulation
chemical_list: D018925:Chemokines; D015850:Interleukin-6; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D014298:Trimethyltin Compounds; D014409:Tumor Necrosis Factor-alpha; C037718:trimethyltin hydroxide