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Intrathecal Injection NMDA Receptor Agonist NMDA Up-regulates COX-2 Expression in the Spinal Dorsal Horn in Rats

Author: ChenZuoNa
Tutor: LiWenBin
School: Hebei Medical University
Course: Pathology and Pathophysiology
Keywords: Cyclooxygenase-2 Pain and hyperalgesia The posterior horn of the spinal cord NMDA NMDA receptor Western blot RT-PCR Rats
CLC: R96
Type: Master's thesis
Year: 2008
Downloads: 107
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Abstract

The purpose: prostaglandin (prostaglandins, PGs), especially prostaglandin E2 and prostacyclin inflammation, pain and fever medium. Cyclooxygenase (cyclooxyganese, COX) is the rate-limiting enzyme in the synthesis of PGs. Noxious stimuli incoming caused pain and hyperalgesia, COX-2 and PGs play an important role. For example, pre-oral or intrathecal administration of the COX-2 inhibitors may be dose-dependent manner to produce anti-nociception role. Studies have shown that application of immunohistochemistry, Western blot method increased spinal COX-2 protein expression in the rat peripheral inflammatory pain and hyperalgesia model, further confirmed that the COX-2 catalyzes the production of PGs in the spinal cord injury an important role in the sexual transmission of information. However, the mechanism of COX-2 expression increased spinal cord in the process is not fully understood. Considerable evidence that excitatory amino acid (excitatory amino acids, EAAs) and their receptors, especially the N-methyl-D-about aspartate (NMDA) receptors play an important role in spinal nociceptive information transfer. At the same time, data show that in the pain and hyperalgesia process of nociceptive inputs caused increase in the angle of COX-2 expression after spinal cord may be associated with the activation of the NMDA receptor. For example, in the process of kaolin and carrageenan and formalin-induced pain and hyperalgesia rat spinal glutamate and PGE2 release; NMDA receptor antagonists and selective COX-2 inhibition. The agents are able to significantly reduce the pain of the formalin test behavior; intrathecal NMDA-induced nociceptive dose-dependently intrathecal or systemic administration of selective inhibition of COX-2 inhibitors. My room using immunohistochemical technology research found that while NOCICEPTION to rat plantar injection of formalin or intrathecal injection of NMDA receptor agonist NMDA induced increase in the spinal dorsal horn COX-2 expression. Intrathecal injection of NMDA receptor noncompetitive inhibitor MK-801 to inhibit the upregulation of COX-2 expression. Preliminary prompted NMDA receptor activity is one of the reasons that the angle of COX-2 expression increased after spinal cord mediated inflammatory pain and hyperalgesia process. This topic is on this basis, Western blot and RT-PCR technique to further observe the intrathecal injection of NMDA receptor agonist NMDA COX-2 protein and mRNA expression to elucidate the NMDA receptor activation in nociceptive Information incoming angle of COX-2 expression increased after causing spinal cord provides further experimental evidence. Methods: 110 male Spague-Dawley rats, weighing 280 ± 20 g, were randomly divided into the following groups: sham group: intrathecal injection of saline 10 μl of. Observation drawn at the appropriate point in time. The NMDA I group: intrathecal injection the NMDA solution of 10μl. 0.1 nmol, 1 nmol, 10 nmol three sub-groups is further divided according to the injected dose of NMDA. Animals in each group was four hours after the intrathecal injection drawn observe NMDA raised dorsal angle of COX-2 expression in a dose-dependent. MK-801 NMDA groups: first intrathecal injection of MK-801 saline solution 10 μl (50 nmol) 15 min after the intrathecal injection of NMDA solution 10μl (10 nmol), 4 hours after injection of NMDA drawn observation MK-801 on NMDA-induced the spinal dorsal horn COX-2 upregulation. The NMDA II group: intrathecal injection of NMDA 10 nmol, after injection, 1 h, 2 h, 4 h, 24-h and 36 h (limited to Western blot analysis), and 3 d (limited to Western blot analysis), determination of the heat The tail-flick latency, latency and mechanical stimuli thermal radiation paw paw threshold sacrificed when the phase characteristics observed after intrathecal injection of NMDA spinal dorsal horn of COX-2 expression and its relationship with hyperalgesia of time corresponding. Each group, each sub-group of 10 animals, including five for the angle of COX-2 protein expression in Western blot detection of spinal cord 5 for RT-PCR detection of spinal cord posterior horn of COX-2 mRNA expression changes. Data are expressed as mean ± standard deviation (x ± s). Using SPSS statistical software for univariate analysis of variance (One-Way ANOVA) and t-test, a significant difference (P lt; 0.05) as judged sexual standards. Results: 1 pain animal behavioral responses in rats after intrathecal injection of NMDA nociceptive behavior characteristic reaction, including the grip of tension, biting, licking, writhing and squeak called. 1.1 thermal drift and thermal withdrawal latency compared with sham group, the thermal tail-flick latency of NMDA 1 h group, 2 h group, 4 h group and 24 h group was significantly shorter (P lt; 0.05), indicating intrathecal injection NMDA early post can occur thermal hyperalgesia and hyperalgesia sustainable long time. NMDA 36 h and 3 d group hot flick latency has basically returned to normal levels, indicating that intrathecal NMDA-induced thermal hyperalgesia has been restored. Thermal withdrawal latency of changes in the characteristics and thermal drift similar. After 36 h, 1.2 mechanical paw withdrawal reflex threshold compared with sham group, 1 h after the the rat intrathecal injection of NMDA mechanical flinching threshold already significantly reduced, this reduction is sustainable to the intrathecal injection of NMDA that intrathecal injection of NMDA After the early stage of mechanical hyperalgesia and hyperalgesia sustainable long time. NMDA 3 d group compared with the sham was no significant difference, indicating that the intrathecal injection of NMDA-induced mechanical hyperalgesia has been restored. Intrathecal injection of NMDA raised dorsal angle of COX-2 expression with rat intrathecal NMDA dose increase (0.1 nmol, 1 nmol and 10 nmol), spinal dorsal horn of COX-2 protein and mRNA expression gradually increased, showed a dose-dependent manner (P lt; 0.05). Pre intrathecal injection of NMDA receptor blockers MK-801 significantly inhibited the above NMDA-induced upregulation of COX-2 expression (P lt; 0.05). Intrathecal injection of NMDA-induced spinal cord after the angle of COX-2 expression raised the time characteristics of time with the pain caused by the behavior characteristics consistent intrathecal injection of NMDA two hours after the spinal dorsal horn of COX-2 protein expression and the control group compared to began to increase 4 h reached a peak, and then gradually lowered to 3 d basically returned to sham level (P lt; 0.05). Intrathecal injection of NMDA, COX-2 mRNA expression in spinal dorsal horn presents a similar result with the COX-2 protein, COX-2 mRNA expression 1 h after the start time is earlier than the upregulation of COX-2 protein, advance to NMDA injection up-regulated mRNA expression restored to sham levels also advance to 24 h (P lt; 0.05). Time characteristics of the COX-2 protein and mRNA in the time course and intrathecal NMDA after pain behavior is consistent. Conclusion: rats, intrathecal NMDA receptor agonist NMDA raised the spinal cord in a dose-dependent manner angle of COX-2 expression 2 This raised the NMDA receptor noncompetitive inhibitor MK-801 inhibited and the intrathecal NMDA caused pain behavior reaction time course characteristics coincide. 3 These results suggest that, in the the nociceptive inputs caused pain and hyperalgesia process of the activity of NMDA receptors in the spinal cord is one of the reasons causing spinal cord angle of COX-2 upregulation.

Intrathecal Injection NMDA Receptor Agonist NMDA Up-regulates COX-2 Expression in the Spinal Dorsal Horn in Rats

Abstract

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