| Objective: Diabetic peripheral neuropathy(DPN) is one of the most common long-time complications of diabetes, and the morbility increases every year. With paying attention to diabetics complication and diagnose development,peripheral sensory neuropathy have been taken more and more seriously and most common。The mechanisms of diabetic neuropathic pain are very complex and not yet been clear. NMDA receptors(NMDARs) are important components of system of spine excitatory glutamic acid receptors。As chronic ache conditions,DPN can shift a series of release of neurotransmitter and receptors activation,which contributing to affecting function of NMDAergic receptors,consequently impressing the nociceptive messages integration,transmission and regulation in spinal cord induced by neuropathic painThe present study is to explore changes of NMDA receptors in spinal cord dorsal horn of rats with diabetic neuropathic pain induced by STZ. Characteristic behavioral changes were observed to affect hyperalgesia of rats between diabetic group and control , including 50% paw withdraw threshold(PWT) of rats with diabetic neuropathic pain.Methods of immunohistochemistry was applied to examine the expression of NMDA receptors in spinal cord dorsal horn. Studies about the changes of NMDA receptors in spinal cord dorsal horn could help finding out more specific targets of treatment for diabetic neuropathic pain.Methods: 35 male Sprague-Dawley rats were randomly selected for this experiment, weighing 130-150g. Body weights, fasting blood glucose level and 50% paw withdraw threshold of all the rats were measured before STZ injection. 26 rats were induced with a single intraperitoneal injection of streptozotocin(50mg/kg) as diabetes. At one week after STZ injection, 21 rats whose fasting blood glucose level increased up to 16.7mmol/L were considered as diabetic rats, and the ratio was 80%. At two week after STZ injection, responses to the mechanical stimulus of diabetic rats were measured with von Frey filament, and whose 58% paw withdraw threshold(PWT) were down to 4g were considered as diabetic neuropathic pain models(the ratio 50%). Another 9 rats were intraperitoneal injected of saline as controls.15 diabetic rats randomly selected and 9 control rats were used to compare the expression of NMDA receptors in the spinal cord dorsal horn. 15 diabetic rats were separated into 3 groups by different time points at 3, 5, 7 weeks after STZ injection.So do the control group and each group has 3 rats. Body weights, fasting blood glucose level and PWT were measured in diabetic and control rats in every time point. At 3, 5, 7 weeks after STZ injection, diabetic rats which PWT were down to 4g were sacrificed and intumescence segments of spinal cord were collected for analysis of NMDA receptors in the spinal cord dorsal horn for immunohistochemistry。The same to 9 control rats.Data analysis and statistic. Data were expressed as mean±SEM. The resu- lts were analyzed by T-test and analysis of variance(ANOVA). Values of P<0.05 were considered as statistically significant.Results:1 Before STZ injection, the level of body weights, fasting blood glucose and 50% paw withdraw threshold had no Statistical difference between diabetic and control groups. To compare with control group, the level of 50% paw withdraw threshold and Body weights in diabetic group decreased dramatically at 3, 5, 7 week after STZ injection (P<0.05);and fasting blood glucose significantly increased after STZ injection in diabetic group (P<0.05)。And they also had significant Statistical difference compared with they were before STZ injection (P<0.05).2 To compare with control group, immunoreactivity for NMDA receptors in the spinal cord dorsal horn of rats with diabetic neuropathic pain significantly increased at 3, 5, 7 week after STZ injection (P<0.05)。Conclusion: NMDA receptors in the spinal cord dorsal horn are involved in the regulation of diabetic neuropathic pain。...
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