Differentiation renders susceptibility to excitotoxicity in HT22 neurons

HT22 is an immortalized mouse hippocampal neuronal cell line that does not express cholinergic and glutamate receptors like mature hippocampal neurons in vivo. This in part prevents its use as a model for mature hippocampal neurons in memory-related studies. We now report that HT22 cells were appropriately induced to differentiate and possess properties similar to those of mature hippocampal neurons in vivo, such as becoming more glutamate-receptive and excitatory. Results showed that sensitivity of HT22 cells to glutamate-induced toxicity changed dramatically when comparing undifferentiated with differentiated cells, with the half-effective concentration for differentiated cells reducing approximately two orders of magnitude. Moreover, glutamate-induced toxicity in differentiated cells, but not undifferentiated cells, was inhibited by the N-methyi-D- aspartate receptor antagonists MK-801 and memantine. Evidently, differentiated HT22 cells expressed N-methyI-D-aspartate receptors, while undifferentiated cells did not. Our experimental findings indicated that differentiation is important for immortalized cell lines to render post-mitotic neuronal properties, and that differentiated HT22 neurons represent a better model of hippocampal neurons than undifferentiated cells.

Neuron-specific enolase expression in a rat model of radiation-induced brain injury following vascular endothelial growth factor-modified neural stem cell transplantation

BACKGROUND： Previous studies have shown that transplantation of vascular endothelial growth factor （VEGF）-modified neural stem cells （NSC） provides better outcomes, compared with neural stem cells, in the treatment of brain damage. OBJECTIVE： To compare the effects of VEGF-modified NSC transplantation and NSC transplantation on radiation-induced brain injury, and to determine neuron-specific enolase （NSE） expression in the brain. DESIGN, TIME, AND SETTING： The randomized, controlled study was performed at the Linbaixin Experimental Center, Second Affiliated Hospital, Sun Yat-sen University, China from November 2007 to October 2008. MATERIALS： VEGF-modified C17.2 NSCs were supplied by Harvard Medical School, USA. Streptavidin-biotin-peroxidase-complex kit （Boster, China） and 5, 6-carboxyfluorescein diacetate succinimidyl ester （Fluka, USA） were used in this study. METHODS： A total of 84 Sprague Dawley rats were randomly assigned to a blank control group （n = 20）, model group （n = 20）, NSC group （n = 20）, and a VEGF-modified NSC group （n = 24）. Rat models of radiation-induced brain injury were established in the model, NSC, and VEGF-modified NSC groups. At 1 week following model induction, 10 pL （5 ×10^4 cells/μL） VEGF-modified NSCs or NSCs were respectively infused into the striatum and cerebral cortex of rats from the VEGF-modified NSC and NSC groups. A total of 10μL saline was injected into rats from the blank control and model groups. MAIN OUTCOME MEASURES： NSE expression in the brain was detected by immunohistochemistry following VEGF-modified NSC transplantation. RESULTS： NSE expression was significantly decreased in the brains of radiation-induced brain injury rats （P 〈 0.05）. The number of NSE-positive neurons significantly increased in the NSC and VEGF-modified NSC groups, compared with the model group （P 〈 0.05）. NSE expression significantly increased in the VEGF-modified NSC group, compared with the NSC group, at 6 weeks following transplantation （P 〈 0.05）. CONCLUSION： VEGF-modified NSC transplantation increased NSE expression in rats with radiation-induced brain injury, and the outcomes were superior to NSC transplantation.

Correlating plasma endothelin-1 and beta-endorphin levels to nine risk factors of acute cerebral infarction

BACKGROUND： Several studies have confirmed that endothelin and endorphin are involved in the occurrence of cerebral vasospasm. However, the correlation of these factors to acute cerebral infarction-related risk factors needs to be confirmed. OBJECTIVE： To detect endothelin-1 （ET-1） and beta-endorphin （β -EP） levels in plasma of patients with acute cerebral infarction, and to analyze the correlations of these factors to smoking, alcohol abuse, hypertension, diabetes mellitus, diseased region, diseased degree, gender, and other factors related to acute cerebral infarction. DESIGN： A case-control observation. SETTING： First Department of Neurology, Guangdong Hospital of Traditional Chinese Medicine; Department of Neurology, Second Affiliated Hospital of Sun Yat-sen University. PARTICIPANTS： Sixty-nine inpatients with acute cerebral infarction were admitted to the Department of Neurology, Second Affiliated Hospital of Sun Yat-sen University （March 2003-January 2004） and First Department of Neurology, Guangdong Hospital of Traditional Chinese Medicine （March July 2004） and recruited for this study. All 69 inpatients corresponded to the diagnosis criteria of acute cerebral infarction, formulated in the National Working Conference of Cerebrovascular Disease in 1998, and were confirmed as acute cerebral infarction by CT/MRI. The patient group consisted of 35 males [（644- 12） years old] and 34 females[ （674- 13 ） years old]. Among them, 9 patients were smokers, 7 were alcohol users, 48 had a history of hypertension, and 16 had a history of diabetes mellitus. CT/MRI examinations revealed that 35 patients presented with left focus sites, 11 with right ones and 23 with bilateral ones. Following attack, 24 patients had Barthel Index Scale grading 〈 40 points, 21 patients 40-50 points, and 24 patients 〉 60 points. An additional 59 healthy individuals, who received health examinations simultaneously, were included as controls. Among the control subjects, there were 37 males [（62±10） years old] and 22 females [（65±11） years old]. Among them, 7 patients were smokers, and 6 were alcohol users. All controls had no history of stroke, hypertension, or diabetes mellitus. Informed consents of laboratory measurements were obtained from all subjects, and this study was approved by the Hospital Ethics Committee. METHODS： ① Following admission, all subjects were scored by Barthel Index Scale （BIS） and Hamilton Depression Scale. Meanwhile, hypertension, diabetes mellitus, gender, smoking, drinking, and other conditions were recorded. CT/MRI examination was conducted to identify the focus site.②On the 2^nd day after admission, ET-1 and β -EP plasma levels were measured with an automatic ET-1 and β -EP analysis kit. MAIN OUTCOME MEASURES： ET-1 and β -EP plasma levels and their correlation to acute cerebral infarction-related factors. RESULTS： Sixty-nine patients with acute cerebral infarction, and an additional 59 healthy individuals participated in the final analysis. β ET-1 [（63.80±27.65） ng/L vs. （46.50±9.36） ng/L, P 〈 0.05] and β - EP [（94.18±33.94） mg/L vs. （51.87±23.43） mg/L, P 〈 0.05] levels of the patient group were obviously higher than respective values of the control group. ② The ET-1 and β -EP levels of patients with cerebral infarction did not correlate to hypertension, diabetes mellitus, BIS, depression, cerebral infarct focus, disease course, gender, smoking or drinking （P 〉 0.05）. CONCLUSION： The ET-I and β-EP levels of patients with acute cerebral infarction increased, but they were not obviously associated with disease course, blood pressure, blood glucose, BIS, or other common cerebral infarction-related factors.