Expression of gamma-aminobutyric acid type A receptor α2 subunit in the dorsal root ganglion of rats with sciatic nerve injury

The γ-aminobutyric acid neurotransmitter in the spinal cord dorsal horn plays an important role in pain modulation through primary afferent-mediated presynaptic inhibition. The weakening of γ-aminobutyric acid-mediated presynaptic inhibition may be an important cause of neuropathic pain. γ-aminobutyric acid-mediated presynaptic inhibition is related to the current strength of γ-aminobutyric acid A receptor activation. In view of this, the whole-cell patch-clamp technique was used here to record the change in muscimol activated current of dorsal root ganglion neurons in a chronic constriction injury model. Results found that damage in rat dorsal root ganglion neurons following application of muscimol caused concentration-dependent activation of current, and compared with the sham group, its current strength and γ-aminobutyric acid A receptor protein expression decreased. Immunofluorescence revealed that γ-aminobutyric acid type A receptor α2 subunit protein expression decreased and was most obvious at 12 and 15 days after modeling. Our experimental findings confirmed that the γ-aminobutyric acid type A receptor α2 subunit in the chronic constriction injury model rat dorsal root ganglion was downregulated, which may be one of the reasons for the reduction of injury in dorsal root ganglion neurons following muscimol-activated currents.     

Effects of progesterone on glutamate transporter 2 and gamma-aminobutyric acid transporter 1 expression in the developing rat brain after recurrent seizures

Seizures were induced by flurothyl inhalation. Rats were intramuscularly treated with progesterone after each seizure. Results demonstrated that glutamate transporter 2 and γ-aminobutyric acid transporter 1 expression levels were significantly increased in the cerebral cortex and hippocampus of the developing rat brain following recurrent seizures. After progesterone treatment, glutamate transporter 2 protein expression was upregulated, but γ-aminobutyric acid transporter 1 levels decreased. These results suggest that glutamate transporter 2 and γ-aminobutyric acid transporter 1 are involved in the pathological processes of epilepsy. Progesterone can help maintain a balance between excitatory and inhibitory systems by modulating the amino acid transporter system, and protect the developing brain after recurrent seizures.     

Effect of propofol on the reactivity of acetylcholinesterase, N-methyl-D-aspartate receptors, and gamma-aminobutyric acid receptors in the hippocampus of aged rats after chronic cerebral ischemia

We induced ischemic brain injury in aging rats to examine the effects of varying doses of propofol on hippocampal activities of acetylcholinesterase,N-methyl-D-aspartate receptors,and γ-aminobutyric acid receptors.Propofol exhibited no obvious impact on acetylcholinesterase activity,but directly activated the γ-aminobutyric acid receptor.The neuroprotective function of propofol on the hippocampus of aging rats following cerebral ischemic injury may be related to altered activities of γ-aminobutyric acid receptors and N-methyl-D-aspartate receptors.     

Cognitive improvement following transvenous adipose-derived mesenchymal stem cell transplantation in a rat model of traumatic brain injury

The effects of adipose-derived mesenchymal stem cell (ADMSC) transplantation for the repair of traumatic brain injury remain poorly understood. The present study observed neurological functional changes in a rat model of traumatic brain injury following ADMSC transplantation via the tail vein. Cell transplants were observed in injured cerebral cortex, and expression of brain-derived nerve growth factor was significantly increased in the injured hippocampus following transplantation. Results demonstrated that transvenous ADMSC transplants migrated to the injured cerebral cortex and significantly improved cognitive function.     

Propofol effectively inhibits lithium-pilocarpine-induced status epilepticus in rats via downregulation of N-methyl-D-aspartate receptor 2B subunit expression

Status epilepticus was induced via intraperitoneal injection of lithium-pilocarpine.The inhibitory effects of propofol on status epilepticus in rats were judged based on observation of behavior,electroencephalography and 24-hour survival rate.Propofol(12.5-100 mg/kg) improved status epilepticus in a dose-dependent manner,and significantly reduced the number of deaths within 24 hours of lithium-pilocarpine injection.Western blot results showed that,24 hours after induction of status epilepticus,the levels of N-methyl-D-aspartate receptor 2A and 2B subunits were significantly increased in rat cerebral cortex and hippocampus.Propofol at 50 mg/kg significantly suppressed the increase in N-methyl-D-aspartate receptor 2B subunit levels,but not the increase in N-methyl-D-aspartate receptor 2A subunit levels.The results suggest that propofol can effectively inhibit status epilepticus induced by lithium-pilocarpine.This effect may be associated with downregulation of N-methyl-D-aspartate receptor 2B subunit expression after seizures.     

Correlation of hypoxia-inducible factor-1 alpha and erythropoietin protein and mRNA to cerebral ischemic tolerance in a focal ischemia/reperfusion model using the twice suture method

BACKGROUND： Numerous studies have shown that transient ischemic preconditioning induces cerebral ischemic tolerance. However, the underlying mechanisms of endogenous protection following ischemic preconditioning remain unclear. OBJECTIVE： To dynamically measure erythropoietin and hypoxia-inducible factor-1α （HIF-1α） mRNA and protein expression at various times following preconditioning, and to investigate effects of erythropoietin and HIF-1α on cerebral ischemic tolerance in a model of focal ischemia/reperfusion established using the twice suture method. DESIGN, TIME AND SETTING： The randomized, controlled study was performed at the Institute of Anatomy, Medical College, Qingdao University, China from March 2006 to March 2007. MATERIALS： Rabbit anti-rat HIF-1α monoclonal antibody and biotinylated goat anti-rabbit IgG （Boster, China）, rabbit anti-rat erythropoietin monoclonal antibody （Santa Cruz Biotechnology, USA）, and one-step RT-PCR kit （Qiagen, Germany） were used in this study. METHODS： A total of 99 healthy, male, Wistar rats were randomly assigned to three groups： sham surgery （n = 9）, non-ischemic preconditioning （n = 45）, and ischemic preconditioning （n = 45）. In the ischemic preconditioning group, rat models of pre-ischemia-reperfusion-ischemia-reperfusion were established by occluding the left middle cerebral artery using the twice suture method. In the non-ischemic preconditioning group, pre-ischemia was replaced by sham surgery. Subsequently, the ischemic preconditioning and non-ischemic preconditioning groups were equally divided into five subgroups according to time of first reperfusion, including 1-, 3-, 7-, 14-, and 21-day subgroups. The sham surgery group received the sham surgery twice. MAIN OUTCOME MEASURES： HIF-la and erythropoietin protein expression was measured in the cerebral cortex, corpus striatum, and hippocampus of the ischemic hemisphere. HIF-1α and erythropoietin mRNA expression were determined in the frontal and parietal cortex of the ischemic hemisphere. RESULTS： （1） Intergroup comparison： compared with the non-ischemic preconditioning group, HIF-1α protein expression significantly increased in the rat cerebral cortex, corpus striatum, and hippocampus in the ischemic hemisphere at 1,3, and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05 or P 〈 0.01）. Erythropoietin protein expression significantly increased in the cerebral cortex, corpus striatum, and hippocampus, as well as HIF-1α and erythropoietin mRNA expression in the frontal and parietal cortex in the ischemic hemisphere, at 3 and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05）. （2） Temporal expression： HIF-1α protein expression in the rat cerebral cortex, corpus striatum, and hippocampus, as well as HIF-la mRNA expression in the frontal and parietal cortex, in the ischemic hemisphere increased at 3 days, and gradually decreased from 7 days following reperfusion in the ischemic preconditioning group. Temporal erythropoietin protein and mRNA expression was consistent with HIF-1α protein expression. （3） Correlation： erythropoietin mRNA expression positively correlated with HIF-1α mRNA expression （r= 0.737, P 〈 0.01）. CONCLUSION： Ischemic preconditioning induced cerebral ischemic tolerance. Pre-ischemiainduced increase in endogenous HIF-1αexpression, as well as its target gene erythropoietin, participated in the formation of cerebral ischemic tolerance.     

降钙素基因相关肽及内皮素A受体与蛛网膜下腔出血

Numerous studies have demonstrated that endothelin-1 combines with endothelin receptor A,resulting in intense vasoconstriction.Although calcitonin gene-related peptide(CGRP) suppresses endothelin-1,CGRP and endothelin receptor A exhibit direct biological effects on brain tissue.The present study analyzed CGRP and endothelin receptor A expression following subarachnoid hemorrhage in rabbits using immunohistochemistry.CGRP expression was significant at 5 days after model establishment,and endothelin receptor A expression was significant at 3 days after model induction.The perimeter of the basilar artery was measured to determine the amount of cerebral vasospasm.Analytical results revealed a significantly shortened basilar artery perimeter following subarachnoid hemorrhage.Changes in the basilar artery perimeter were negatively associated with endothelin receptor A expression,but positively correlated with CGRP expression in vessels.These results suggest that following subarachnoid hemorrhage,CGRP and endothelin receptor A expressions dynamically changed in brain vessels and tissues,although these changes were not synchronous.Changes in endothelin receptor A expression exhibited a significant effect on the occurrence and development of delayed cerebral vasospasm and delayed neuronal death,while CGRP relaxed vessels and protected nerves.     

Edema and neuronal apoptosis in the hippocampus and cortex of elderly rats following transient cerebral ischemia/reperfusion injury

BACKGROUND： Previous studies of cerebral ischemia have used young animals, with an ischemic time greater than 5 minutes （safe time limit）. Despite an increased understanding of neuronal apoptosis, it remains uncertain whether brief cerebral ischemic events of 5 minutes or less damage brain tissue in elderly rodents. OBJECTIVE： To investigate the effects of transient cerebral ischemia （5 minutes）/reperfusion injury on brain cortical and hippocampal edema, aquaporin-4 （AQP-4） expression, and neuronal apoptosis in aged rats, and to compare ischemic sensitivity between cortex and hippocampus. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Institute of Cerebrovascular Disease, Qingdao University Medical School from April 2008 to March 2009. MATERIALS： Rabbit anti-AQP-4 polyclonal antibody, TUNEL kit, and SABC immunohistochemistry kit were purchased from Wuhan Boster Bioengineering, China. METHODS： A total of 160 healthy, male, aged 19-21 months, Wistar rats were randomly assigned to 4 groups： sham-surgery, and ischemia 1-, 3-, and 5-minute groups, with 40 rats in each group. The global cerebral ischemia model was established using the Pusinelli four-vessel occlusion, and the three cerebral ischemia groups were subdivided into reperfusion 12-hour, 1-, 2-, 3-, and 7-day subgroups, with 8 rats in each subgroup. The sham-surgery group was subjected to exposure of the first cervical bilateral alar foramina and bilateral common carotid arteries. MAIN OUTCOME MEASURES： The dry-wet weight assay was used to measure brain water content and histopathology of the cortex and hippocampus was observed following hematoxylin-eosin staining. In addition, cortical and hippocampal AQP-4 expression was detected by streptavidin-biotin complex immunohistochemistry, and neuronal apoptosis was detected by the TUNEL method. RESULTS： There was no significant difference in brain water content or AQP-4 expression in the cortex and hippocampus between ischemia 1- and 3-minute groups and the sham-surgery group or brain water content or AQP-4 expression in the cortex between ischemia 5-minute group and sham-surgery group （P 〉 0.05）. However, brain water content and AQP-4 expression in the hippocampus after 5 minutes of cerebral ischemia were significantly increased compared with the sham-surgery group （P 〈 0.05 or P 〈 0.01）. Several TUNEL-positive cells were observed in the cortex and hippocampus of the sham-surgery group and ischemia 1-minute group, as well as in the cortex of the ischemia 3-minute group. In addition, the number of apoptotic neurons in the hippocampus of ischemia 3-minute group and in the cortex and hippocampus of ischemia 5-minute group was significantly increased （P 〈 0.05 or P 〈 0.01 ）. Neuronal apoptosis was increased after 12 hours of ischemia/reperfusion, and it reached a peak by 2 days （P 〈 0.01）. CONCLUSION： Transient cerebral ischemia （5 minutes） resulted in increased hippocampal edema, AQP-4 expression, and neuronal apoptosis. Moreover, cerebral ischemia had a greater effect on neuronal apoptosis than brain edema or AQP-4 expression, and the hippocampus was more sensitive than the cortex.     

Oxymatrine reduces neuroinflammation in rat brain A signaling pathway

Cerebral neuroinflammation models were established by injecting 10 μg lipopolysaccharide into the hippocampus of male Sprague-Dawley rats. The rats were treated with an intraperitoneal injection of 120, 90, or 60 mg/kg oxymatrine daily for three days prior to the lipopolysaccharide injection. Twenty-four hours after model induction, the hippocampus was analyzed by real-time quantitative PCR, and the cerebral cortex was analyzed by enzyme-linked immunosorbent assay and western blot assay. The results of the enzyme-linked immunosorbent assay and the real-time quantitative PCR showed that the secretion and mRNA expression of the pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α were significantly decreased in the hippocampus and cerebral cortex of model rats treated with oxymatrine. Western blot assay and real-time quantitative PCR analysis indicated that toll-like receptor 4 mRNA and protein expression were significantly decreased in the groups receiving different doses of oxymatrine. Additionally, 120 and 90 mg/kg oxymatrine were shown to reduce protein levels of nuclear factor-κB p65 in the nucleus and of phosphorylated IκBα in the cytoplasm of brain cells, as detected by western blot assay. Experimental findings indicate that oxymatrine may inhibit neuroinflammation in rat brain via downregulating the expression of molecules in the toll-like receptor 4/nuclear factor-κB signaling pathway.