ObjectivesTo investigate the expression of glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein homologous protein (CHOP) and cysteine asparate protease-12 (caspase-12) and neuronal apoptosis in the brain of zebraifsh larvae after hypoxia reperfusion, and the neuroprotective effect of taurine.Methods Five day old post-fertilization zebraifsh larvae were randomly assigned into 3 groups, control group, hypoxia reperfusion group (model group) and taurine group, and the taurine group was further divided into 3 subgroups according to different concentrations (1 mmol/L, 5 mmol/L, 10 mmol/L) with 100 zebraifsh larvae each. The behavior, recovery time and median survival time of those zebraifsh larvae after hypoxia with 1h reperfusion were observed and recorded. The pathological changes and apoptosis of neurons were detected by Nissl staining and terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling. The expression of GRP78, CHOP and caspase-12 in the brain of zebrafish larvae were detected by Western blot.Results Compared with the model group, the recovery time was shortened, the median survival time was extended, the Nissl stained neurons was increased and the apoptotic neurons were decreased in the taurine groups. GRP78, CHOP and caspase-12 were expressed in model group and taurine group. The expression of GRP78, CHOP and caspase-12 was much lower in taurine group than in model group.Conclusions Hypoxia reperfusion may induce endoplasmic reticulum stress and taurine may be neuroprotective against hypoxia reperfusion by down-regulating GRP78, CHOP and caspase-12.

As an inhibitory amino acid similar to gama-aminobutyric acid,taurine can activate the corticostriatal pathway as an endogenous ligand for glycine receptors,establishing equilibrium between the excitatory and inhibitory processes in the brain.In mammalian brains,taurine concentrations increase during the developmental period of the brain until weaning,and subsequently decline reaching stable concentrations in adulthood.With abilities of anti-oxidative stress,anti-inflammatory and anti-apoptosis,taurine can improve the hypoxic-ischemic brain injury,promote the proliferation and differentiation of neurons and affect brain development,It needs more investigations to prove when and how taurine supplementation during gestation,baby,children or adult can assist the development of the brain and prevent the damage of the brain from hypoxic and ischemic damage.

Objective To investigate the expression of endoplasmic reticulum stress - related factors, glucose - regulated protein 78(GRP78)and growth arrest and DNA damage - inducible protein 34( GADD34)and neuronal apoptosis in the brain of zebrafish larvae after hypoxia/ reoxygenation brain injury,and the neuroprotective role of Taurine. Methods The 5 day post - fertilization zebrafish larvae were randomly assigned to 3 groups:control group, hypoxia/ reoxygenation model group(model group)and Taurine treatment group(Taurine group). According to the dif-ferent time points for observation,each group was subdivided into 5 subgroups(1 h,3 h,6 h,24 h,48 h)with 100 ze-brafish larvae each. The pathological changes in the brain tissues and cell apoptosis were detected by fluorescence ter-minal deoxynucleotidyltransferase - mediated dUTP nick end - labeling( TUNEL). The expression of GRP78 and GADD34 mRNA in the brain of zebrafish larvae were detected by real - time quantitative reverse transcription PCR (qRT - PCR). The changes in GRP78 and GADD34 protein were detected by Western blot. Results (1)TUNEL:apoptosis index(AI)was increased after hypoxia/ reoxygenation,and reached the peak at 3 h in model group,the AI in Taurine group was decreased compared with that in the model group at the same time point(1 h:22. 83 ± 1. 80 vs 30. 18 ± 1. 81,3 h:23. 22 ± 2. 46 vs 42. 97 ± 4. 01,6 h:16. 80 ± 1. 69 vs 22. 97 ± 1. 91,all P ﹤ 0. 05).(2)qRT -PCR:the expression of GRP78 and GADD34 mRNA was increased at 1 h after hypoxia/ reoxygenation,and reached the peak at 3 h in the model group,the expression in Taurine group was decreased compared with that in the model group at the same time point(GRP78 mRNA:1 h:2. 35 ± 0. 13 vs 5. 36 ± 0. 35,3 h:3. 08 ± 0. 33 vs 4. 27 ± 0. 52,6 h:1. 57 ± 0. 12 vs 3. 00 ± 0. 13,all P ﹤ 0. 05;GADD34 mRNA:1 h:5. 14 ± 0. 55 vs 7. 45 ± 0. 67,3 h:2. 79 ± 0. 58 vs 5. 83 ± 0. 51,6 h:1. 79 ± 0. 22 vs 3. 67 ± 0. 30,all P ﹤ 0. 05).(3)Western blot:the expression of GRP78 and GADD34 pro-tein was increased at 1 h,reached the peak at 6 h,but it was decreased in Taurine group(GRP78 protein:1 h:1. 12 ± 0. 11 vs 1. 37 ± 0. 13,3 h:0. 79 ± 0. 11 vs 1. 25 ± 0. 10,6 h:0. 55 ± 0. 10 vs 1. 52 ± 0. 14,all P ﹤ 0. 05;GADD34 pro-tein:1 h:0. 92 ± 0. 11 vs 1. 11 ± 0. 13,3 h:0. 96 ± 0. 11 vs 1. 52 ± 0. 09,6 h:0. 76 ± 0. 05 vs 1. 89 ± 0. 06,all P ﹤0. 05).(4)The expression of GRP78 and GADD34 protein was positively correlated with AI in the model group(r =0. 53,0. 56 respectively,all P ﹤ 0. 05). Conclusion One of neuroprotective mechanisms of Taurine against hypoxia/reoxygenation brain injury may down - regulate GRP78 and GADD34 expression.