Effect of Ketamine on the Expression of GABA_B and BDNF in Hippocampus in Rats with Diabetic Neuropathic Pain with Depression
|School||Hebei Medical University|
|Keywords||Ketamine GABABreceptor BDNF diabetic neuropathicpain depression|
Objective: The diabetic peripheral neuropathic pain is one of the mostcommon long-time complications of diabetes. About7.5%-24%of diabeticpatients suffer chronic peripheral neuropathic pain. Its incidence showed anincreasing trend, affecting people’s quality of life and mental health seriously.Depression as a common mood disorder related to chronic pain closely. Lackof effective measures and drugs for diabetic neuropathic pain with depressionup to date. Ketamine as a noncompetitive NMDA receptor antagonist, not onlyhas significant analgesic effect, but also has a rapid and sustainedantidepressant effect. But the exact analgesia and antidepressant mechanism ofketamine is unclear, so study its mechanism can provide reference for betterclinical application.Studies show that: the hypothalamus, hippocampus, cerebral cortex andother areas downregulation of GABABreceptor in the formation of depression,anxiety, addiction plays an important role. And spinal cord of diabeticneuropathic pain rats GABABreceptor downregulation play an important partin the form and maintenance of pain. Another study found that in pain withdepression, hippocampus, thalamus, neurons in the cerebral cortex and otherareas release BDNF significantly reduced. After administration ofantidepressant treatment, which showed high expression until it returns tonormal. But in the course of antidepressant and analgesia of ketamine, thechanges of GABABreceptor and BDNF in the hippocampus are unclear. Inthis study, use STZ and forced swimming test to prepare the model of diabeticneuropathic pain with depression.Methods of immunohistochemistry,RT-PCR and Western blot were applied to examine the expression of GABABreceptors and BDNF in hippocampus. To explore the possible antidepressant and analgesia mechanism of ketamine.Methods: Thirty male Sprague-Dawley rats were randomly selected forthis experiment, weighing180-200g, provided by the Experimental AnimalCenter of Hebei Medical University,were randomly divided into two groups:normal control group(C group) and Diabetic neuropathic pain (DNP) modelgroup(D group), which rats were intraperitoneal injection saline orstreptozocin(STZ) respectively.20rats were intraperitoneal injection STZ,two weeks later,16rats, fasting blood glucose>16.7mmol/L, achieved theeligibility criteria. Diabetic rats use15min forced swimming test (weekly) toform depression model, Method: the rats were placed in high40cm,20cmdiameter cylindrical transparent tank, the depth of25cm, water temperature25±2℃, the water from the tank on the edge of10cm, swimming15min. Threeweeks later, von Frey Hairs mechanical paw withdrawal threshold wasmeasured (PWT), PWT <4g were qualified rat model of neuropathic pain(Dgroup). The group C and group D, record their immobility time into the watertimer5min. Compared with group C rats, IMFST significantly prolongindicates DNP depressive mode model successfully prepared. Combinebehavior and molecular biology change to determine the DNP with depressivein rats.100male SD rats were randomly divided into two groups: normalcontrol group(C group, n=20) and model group(D group, n=80), The modelrats were randomly divided into4groups (n=20, each group) according to theinjection medicines: model control group (D1group): saline; ketaminegroup (D2): Ketamine10mg/kg; NMDA group (D3): NMDA15mg/kg;ketamine+NMDA group (D4): ketamine10mg/kg+NMDA15mg/kg.Intramuscular injection one week. The first day afteradministration (T1), the two weeks after administration (T2), measure PWTand immobility time of forced swimming test. The hippocampus of rat wasremoved after measurement of PWT and immobility time of forced swimmingtest in T1, T2for detection of GABAB receptor and BDNF.Results:1Two weeks after intraperitoneal injection STZ,16rats in20fasting glucose>16.7mmol/L, diabetes model was successful. Above16rats after a15min forced swimming test, measured PWT and IMFST in threeweeks after injection STZ, of which10rats PWT <4g,DNP model weresuccessful, and its IMFST>150s. Compared with normal group, DNP grouprats PWT was significantly lower (13.3±1.7vs3.1±0.8; P <0.05), IMFSTsignificantly longer (49±6vs182±13; P <0.05), their hippocampusBDNF-positive cells was significantly reduced (36.10±3.4vs17.5±2.8; P<0.05); BDNF mRNA levels significantly decreased (0.91±0.06vs0.55±0.08; P <0.05); BDNF protein expression was significantly decreased (1.12±0.06vs0.55±0.08; P <0.05). Therefore, when the behavior of rat wasmeasured PWT diabetes <4g and IMFST>150s, its hippocampus BDNFexpression was significantly decreased, indicating that DNP with depressivemodel was successful.2Compared with group C, the PWT was lower (P<0.05), immobility time of forced swimming test was significantly longer (P<0.05), the expression of GABABreceptor was decreased (P <0.05), theexpression of BDNF was decreased (P <0.05) in group D; compared withD1, the PWT was significantly higher (P <0.05), immobility time of forcedswimming test was significantly shorter (P <0.05), the expression ofGABABreceptor was significantly increased (P <0.05), the expression ofBDNF significantly increased (P <0.05); compared with D1, D3, D4groupPWT, the immobility time of forced swimming test, the expression of GABABreceptors and BDNF showed no significant change.Conclusion: Ketamine as a NMDA receptors antagonist can upregulatethe expression of GABABand BDNF in rats with diabetic neuropathic painwith depression, inhibit diabetic neuropathic pain and depression symptoms.