ABSTRACT
@#Objective To investigate the effect of hyperbaric oxygen (HBO) on the behaviors, organizational morphology and the expression of protein kinase R-like ER kinase (PERK) in rats with spinal cord injury. Methods Thirty-six male Sprague-Dawley rats were randomly divided into normal group, sham group, model group and HBO group, with nine cases in each group. The normal group did not receive any treatment, the sham group received only laminectomy, and the other two groups were established spinal cord injury model with modified Allen's method. Six hours after operation, the model group was treated with regular air, and HBO group received HBO treatment for seven days. The recovery of locomotor function was evaluated by BBB (Basso Beattie and Bresnahan) on the day before operation and six hours, three days, seven days after operation. HE staining was used to observe the change of tissue morphology in injured spinal cord, and the expression of PERK in spinal cord was detected by Western blotting. Results There was no neurological deficit in the normal group and the sham group. The neurological score was lower in the model group than in the sham group three days and seven days after operation (P < 0.05), and was higher in HBO group than in the model group seven days after operation (P < 0.05). There was no obvious structural change in the normal group and the sham group, however, the model group showed swelling cells, condensed cytoplasm, and nucleus pycnosis hyperchromatic, and the HBO group showed slighter swelling cell compared with the model group. The expression of PERK was higher in the model group than in the sham group, and was lower in HBO group than in the model group seven days after operation (P < 0.05). Conclusion HBO could reduce the expression of PERK in the injured spinal cord, and improve the recovery of hind limb locomotor function in spinal cord injury rats.
ABSTRACT
Objective To investigate the effect and mechanism of phosphorylated protein kinase R-like ER kinase(p-PERK) and C/EBP homologous protein(CHOP) after hypoxic-ischemic brain damage ( HIBD) . Methods Neonatal 7-day-old Sprague Dawley rats were divided into sham-operation control group and HIBD group( n=30 per group) . Each group was divided into 0 h,6 h and 24 h subgroup after operation ( n=10 per group) . The ratio of apoptosis of brain cell was measured by flow cytometer and the expression of p-PERK and CHOP were detected by Western blot. Results (1)Apoptosis cell appeared at 6 h in HIBD group,the ratio of cell apoptosis was(2. 17 ± 0. 19)%. The apoptosis cell obvious increased at 24 h,the ratio of cell apoptosis was(13. 42 ± 0. 83)%. There was a significant increase in the ratio of apoptosis after HIBD 6 h and 24 h, as compared with sham-operation control group [ ( 0. 57 ± 0. 06 )%( P <0. 01 ) ] . ( 2 ) The expression of both p-PERK and CHOP was very low in sham-operation control group. In the HIBD group,the expression of both p-PERK and CHOP began to increase at 6 h and increased furthermore at HIBD 24 h. The differences in the expression levels of p-PERK and CHOP in HIBD group among different time points were significant( P<0. 01 ) . ( 3 ) The expression of p-PERK positively correlated with the expression of CHOP (r=0. 997,P< 0. 05). Conclusion With the emerging of apoptosis after HIBD,the expression of both p-PERK and CHOP increases. The imbalance in the expression of PERK induces the apoptosis of brain cells in the HIBD of neonatal rats by regulation of CHOP expression.
ABSTRACT
Objective To investigate the role of endoplasmic reticulum stress (ERS) pathway involving protein kinase R-like ER kinase (PERK)-activating transcription factor 4 (ATF4)-CCAAT/enhancer binding protein homologous protein (CHOP) in apoptosis in lungs of rats with bronchopulmonary dysplasis (BPD).Methods Forty eight premature SD rats were divided into BPD group and control group according to random number table.Rats in BPD group were continually exposed to O2 with volumetric concentration factor of 850 mL/L,while rats in control group were exposed to air.Lung tissues in each group were obtained in 7,14 and 21 days respectively.The apoptosis in lung cells was evaluated by terminal dexynucleotifyl transferase-mediated dUTP nick end labeling (TUNEL) assay.The mRNA levels of glucose regulated protein 78 (GRP78),PERK,ATF4 and CHOP were detected by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR).The protein levels of GRP78,phosphorylated PERK (pho-PERK),ATF4 and CHOP were detected by using Western blot.Results Compared with control group,the lung cells of the rats in BPD group developed more serious apoptosis.Furthermore,the apoptosis index (AI) in lung cells of the rats increased rapidly with the hyperoxia exposure time.This had been statistically verified by comparison with the control group at different timing(7 d:15.50 ± 0.58 vs 1.25 ± 0.50,14 d:27.75 ± 1.71 vs 3.25 ± 0.96,21 d:50.50 ±3.70 vs 4.00 ± 1.15 ;t =57.00,20.58,25.16,all P ＜0.01).The mRNA levels of GRP78,PERK,ATF4 and CHOP in BPD group increased significantly compared to the control group [GRP78:7 d (33.88 ± 3.73) vs (11.65 ± 1.00),14 d (54.50 ±2.18)vs(12.84 ± 1.41),21 d (95.34 ± 7.61)vs(12.43 ±0.59) ;PERK:7 d (5.23 ±0.92)vs (1.45 ±0.46),14 d (7.60 ± 1.56)vs(2.18 ±0.97),21 d (16.55 ±0.50)vs(2.90 ± 1.18) ;ATF4:7 d (23.04 ± 2.45)vs(12.56 ±2.81),14 d (28.66 ±2.66)vs(15.18 ±2.92),21 d (36.63 ±2.99)vs(15.14 ±2.09) ;CHOP:7 d (2.21 ±0.19)vs(0.81 ±0.02),14 d (4.19 ±0.17)vs(0.90 ±0.08),21 d (6.08 ±0.38)vs(0.88 ±0.10) ;all P ＜ 0.05].The protein levels of GRP78,pho-PERK,ATF4 and CHOP in BPD group increased significantly as well [GRP78:7 d (1.33 ±0.03)vs(0.85 ±0.04),14 d (1.31 ±0.02)vs(0.92 ±0.01),21 d (1.82 ±0.28)vs(0.87 ± 0.01);pho-PERK:7 d (0.68±0.02)vs(0.54±0.01),14 d (1.04±0.01)vs(0.65±0.01),21 d (1.29± 0.02)vs(0.73 ±0.01) ;ATF4:7 d (1.26 ±0.01) vs(0.83 ±0.01),14 d (1.39 ±0.02) vs (0.87 ±0.02),21 d (1.67 ±0.02)vs(0.94 ±0.02) ;CHOP:7 d (1.37 ±0.01)vs(0.47 ±0.06),14 d (1.50 ±0.04)vs(0.74 ±0.05),21 d (1.61 ± 0.03) vs (0.55 ± 0.02) ; all P ＜ 0.05].Positive correlation was demonstrated between the expression levels of CHOP protein and AI,PERK,ATF4 in the BPD group (r =0.87,0,92,0.93 respectively,all P ＜ 0.05).Conclusion PERK-ATF4-CHOP mediated ERS may participate in and contribute to the apoptosis mechanism in lungs of rats with BPD.