title: [Intrathecal injection of MK-801 inhibited the NOS activity and NO content of hippocampus in rat during the process of formalin-induced inflammatory pain].
abstract: OBJECTIVE
  To study the effect of intrathecal injection of MK-801, a NMDA receptor antagonist, on the NOS activity and NO content of hippocampus in rat during the process of formalin-induced inflammatory pain as well as the pain behavior of rat.
  
  
  METHODS
  The degree of pain was determined by observing the time of licking and biting the injected paw. NOS expression in the hippocampus was determined by using NADPH-d histochemical staining. NO content of hippocampus was determined by assaying NO3; and NO2.
  
  
  RESULTS
  Subcutaneous injection of formalin elicited a characteristic pain behavioural response consisting of licking and biting the injected paw, etc. Intrathecal injection of MK-801 could shorten obviously the time of licking and biting representing pain behavioural response in phase 2. It is suggested that intrathecal injection of MK-801 could block the pain behavioural response induced by formalin (P < 0.05). The number and staining degree of NADPH-d positive neurons in formalin group significantly increased at 12 h after the formalin injection in CA1, CA2-3 and DG of hippocampus compared with control group as well as NO content, however, the number and staining degree of NADPH-d positive neurons in formalin + MK-801 group significantly decreased in contrast to those of formalin 12 h group as well as the NO content (P < 0.01).
  
  
  CONCLUSIONS
  Intrathecal injection of NMDA receptor antagonist MK-801 could inhibit the NOS activity and NO production in hippocampus of rat, which showed the increase of hippocampal NO production was mainly induced by the peripheral nociceptive information input.
authors.affiliation: Department of Pathophysiology, Basic Medical college, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Ling-yun
authors.initials: LY
authors.lastname: Liu
authors.forename: Qing-jun
authors.initials: QJ
authors.lastname: Li
authors.forename: Yu-yan
authors.initials: YY
authors.lastname: Hu
authors.forename: Xin-hua
authors.initials: XH
authors.lastname: Guo
authors.forename: Sai-chun
authors.initials: SC
authors.lastname: Chu
authors.forename: Wen-bin
authors.initials: WB
authors.lastname: Li
mesh_terms: D000818:Animals; D016291:Dizocilpine Maleate / Q000008:administration & dosage / Q000494:pharmacology*; D005557:Formaldehyde; D006624:Hippocampus / Q000378:metabolism* / Q000503:physiopathology; D007249:Inflammation / Q000139:chemically induced; D007278:Injections, Spinal; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D005557:Formaldehyde; D009569:Nitric Oxide; D016291:Dizocilpine Maleate; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat