title: Spinal astrocytic activation contributes to mechanical allodynia in a rat model of cyclophosphamide-induced cystitis.
abstract: Previous studies have demonstrated that glial cells play an important role in the generation and maintenance of neuropathic pain. Activated glial cells produce numerous mediators such as proinflammatory cytokines that facilitate neuronal activity and synaptic plasticity. Similarly, bladder pain syndrome/interstitial cystitis shares many characteristics of neuropathic pain. However, related report on the involvement of spinal glia in bladder pain syndrome/interstitial cystitis-associated pathological pain and the underlying mechanisms are still lacking. The present study investigated spinal glial activation and underlying molecular mechanisms in a rat model of bladder pain syndrome/interstitial cystitis.
  
  
  
  A rat model of bladder pain syndrome/interstitial cystitis was established via systemic injection with cyclophosphamide. Mechanical allodynia was tested with von Frey monofilaments and up-down method. Moreover, Western blots and double immunofluorescence were used to detect the expression and location of glial fibrillary acidic protein, OX42/Iba1, P-P38, NeuN, interleukin (IL)-1β, phosphorylation of N-methyl-D-aspartate receptor 1 (P-NR1), and IL-1 receptor I (IL-1RI) in the L6-S1 spinal cord. We found that glial fibrillary acidic protein rather than OX42/Iba1 or P-P38 was significantly increased in the spinal cord of cyclophosphamide-induced cystitis. L-alpha-aminoadipate but not minocycline markedly attenuated the allodynia. Furthermore, we found that spinal IL-1β was dramatically increased in cyclophosphamide-induced cystitis, and activated astrocytes were the only source of IL-1β release, which contributed to allodynia in cystitis rats. Besides, spinal P-NR1 was statistically increased in cyclophosphamide-induced cystitis and only localized in IL-1RI positive neurons in spinal dorsal horn. Additionally, NR antagonist significantly attenuated the cystitis-induced pain. Interestingly, the time course of the P-NR1 expression paralleled to that of IL-1β or glial fibrillary acidic protein.
  
  
  
  Our results demonstrated that astrocytic activation but not microglial activation contributed to the allodynia in cyclophosphamide-induced cystitis and IL-1β released from astrocytes might bind to its endogenous receptor on the neurons inducing the phosphorylation of NR1 subunit, leading to sensory neuronal hyperexcitability and pathological pain.
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Bolong
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Rehabilitation, The Third Affiliated Hospital·and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Minzhi
authors.initials: M
authors.lastname: Su
authors.affiliation: Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: ShaoJun
authors.initials: S
authors.lastname: Tang
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China Xiangfuzhou1962@163.com.
authors.forename: Xiangfu
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Hailun
authors.initials: H
authors.lastname: Zhan
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Wenbiao
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Tengcheng
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Urology, The Third Affiliated Hospital and Lingnan Hospital of the Sun Yat-Sen University, Guangzhou, China.
authors.forename: Juncong
authors.initials: J
authors.lastname: Xie
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D003520:Cyclophosphamide / Q000494:pharmacology*; D003556:Cystitis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006930:Hyperalgesia / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D009437:Neuralgia / Q000378:metabolism*; D009457:Neuroglia / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010147:Pain Measurement / Q000379:methods; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism
chemical_list: D016207:Cytokines; D016194:Receptors, N-Methyl-D-Aspartate; D003520:Cyclophosphamide
keywords: Bladder pain syndrome; N-methyl-D-aspartate receptor; cystitis; cytokines; glia; pain; spinal cord