title: Peripheral nerve injury leads to working memory deficits and dysfunction of the hippocampus by upregulation of TNF-α in rodents.
abstract: Patients with chronic pain usually suffer from working memory deficits, which may decrease their intellectual ability significantly. Despite intensive clinical studies, the mechanism underlying this form of memory impairment remains elusive. In this study, we investigated this issue in the spared nerve injury (SNI) model of neuropathic pain, a most common form of chronic pain. We found that SNI impaired working memory and short-term memory in rats and mice. To explore the potential mechanisms, we studied synaptic transmission/plasticity in hippocampus, a brain region critically involved in memory function. We found that frequency facilitation, a presynaptic form of short-term plasticity, and long-term potentiation at CA3-CA1 synapses were impaired after SNI. Structurally, density of presynaptic boutons in hippocampal CA1 synapses was reduced significantly. At the molecular level, we found that tumor necrosis factor-α (TNF-α) increased in cerebrospinal fluid, in hippocampal tissue and in plasma after SNI. Intracerebroventricular or intrahippocampal injection of recombinant rat TNF mimicked the effects of SNI in naive rats, whereas inhibition of TNF-α or genetic deletion of TNF receptor 1 prevented both memory deficits and synaptic dysfunction induced by SNI. As TNF-α is critical for development of neuropathic pain, we suggested that the over-production of TNF-α following peripheral nerve injury might lead to neuropathic pain and memory deficits, simultaneously.
authors.affiliation: Department of Physiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Ren
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhong
authors.forename: Rui-Ping
authors.initials: RP
authors.lastname: Pang
authors.forename: Wen-Jun
authors.initials: WJ
authors.lastname: Xin
authors.forename: Xu-Hong
authors.initials: XH
authors.lastname: Wei
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: He-Quan
authors.initials: HQ
authors.lastname: Zhu
authors.forename: Chang-You
authors.initials: CY
authors.lastname: Wu
authors.forename: Zhi-Hai
authors.initials: ZH
authors.lastname: Qin
authors.forename: Guosong
authors.initials: G
authors.lastname: Liu
authors.forename: Xian-Guo
authors.initials: XG
authors.lastname: Liu
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology*; D006930:Hyperalgesia / Q000209:etiology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D017774:Long-Term Potentiation; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008569:Memory Disorders / Q000209:etiology*; D008570:Memory, Short-Term / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D010523:Peripheral Nervous System Diseases / Q000150:complications / Q000378:metabolism / Q000473:pathology; D017729:Presynaptic Terminals / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000172:deficiency; D018709:Statistics, Nonparametric; D013792:Thalidomide / Q000494:pharmacology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
chemical_list: D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D013792:Thalidomide