Neuropathic pain-induced depressive-like behavior and hippocampal neurogenesis and plasticity are dependent on TNFR1 signaling

Anna Dellarole, Paul Morton, Roberta Brambilla, Winston Walters, Spencer Summers, Danielle Bernardes, Mariagrazia Grilli, John R. Bethea

Research output: Contribution to journalArticle

69 Scopus citations

Abstract

Patients suffering from neuropathic pain have a higher incidence of mood disorders such as depression. Increased expression of tumor necrosis factor (TNF) has been reported in neuropathic pain and depressive-like conditions and most of the pro-inflammatory effects of TNF are mediated by the TNF receptor 1 (TNFR1). Here we sought to investigate: (1) the occurrence of depressive-like behavior in chronic neuropathic pain and the associated forms of hippocampal plasticity, and (2) the involvement of TNFR1-mediated TNF signaling as a possible regulator of such events. Neuropathic pain was induced by chronic constriction injury of the sciatic nerve in wild-type and TNFR1-/- mice. Anhedonia, weight loss and physical state were measured as symptoms of depression. Hippocampal neurogenesis, neuroplasticity, myelin remodeling and TNF/TNFRs expression were analyzed by immunohistochemical analysis and western blot assay.We found that neuropathic pain resulted in the development of depressive symptoms in a time dependent manner and was associated with profound hippocampal alterations such as impaired neurogenesis, reduced expression of neuroplasticity markers and myelin proteins. The onset of depressive-like behavior also coincided with increased hippocampal levels of TNF, and decreased expression of TNF receptor 2 (TNFR2), which were all fully restored after mice spontaneously recovered from pain. Notably, TNFR1-/- mice did not develop depressive-like symptoms after injury, nor were there changes in hippocampal neurogenesis and plasticity.Our data show that neuropathic pain induces a cluster of depressive-like symptoms and profound hippocampal plasticity that are dependent on TNF signaling through TNFR1.

Original languageEnglish
Pages (from-to)65-81
Number of pages17
JournalBrain, Behavior, and Immunity
Volume41
Issue number1
DOIs
StatePublished - 2014

Keywords

  • Cytokines
  • Depression
  • Myelin
  • Neurogenesis
  • Neuropathic pain
  • Plasticity
  • TNF
  • TNFR1

ASJC Scopus subject areas

  • Immunology
  • Behavioral Neuroscience
  • Endocrine and Autonomic Systems

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