Changes in molecular chaperone-mediated autophagy expression of developmental rats after recurrent-status seizures / 中华实用儿科临床杂志

ABSTRACT

Objective:To observe the expression of molecular chaperone-mediated autophagy in hippocampal neurons and its relationship with brain injury after recurrent-status seizures.Methods:Seven-day-old SD rats were divided into two groups according to simple randomization the control group (NS group, 6 rats) and the recurrent-seizure group (RS group, 39 rats). Rats in the RS group were subjected to recurrent seizures after repeated inhalation of flurothyl, with 30 minutes once each day for consecutive 7 days.A total of 30 convulsive models were successfully established (9 rats that failed to establish models were discarded), and they were further divided into 0 h, 1.5 h, 3 h, 12 h and 24 h after the last seizure according to simple randomization, with 6 rats in each group.Western blot and reverse transcription-polymerase chain reaction (RT-PCR) were adopted for the observation of the expression of molecular chaperone-mediated autophagy markers [heat shock cognate protein 70 (Hsc70), lysosome-associated membrane protein type 2a (LAMP-2a), heat shock protein 40(HSP40) and heat shock protein 90(HSP90)] in hip-pocampal neurons, and apoptosis was detected by TdT-mediated dUTP nick-end labeling (TUNEL).Results:(1) RT-PCR and Western blot showed that, compared with the NS group, the expression of Hsc70, as a molecular chape-rone, started to increase at 1.5 h and continued until 24 h after the last seizure in the RS group ( P<0.05). HSP90 increased immediately after the last seizure and lasted until 24 h after the seizure ( P<0.01); the expression of HSP40 and LAMP-2a also showed high expression after the last seizure episode ( P<0.05). (2) The TUNEL method showed that the number of apoptotic cells in the hippocampal CA1 region increased significantly at 3 h (36.33±5.16)/40 field, 12 h (44.83±4.83)/40 field and 24 h (54.83±7.16)/40 field after the last seizure compared with NS group(15.16±2.48)/40 field ( P<0.01). (3) Pearson correlation analysis showed that the level of apoptosis in hippocampal CA1 region of rats after recurrent seizures was positively correlated with the expression of molecular chaperone marker molecules (Hsc70 r=0.734, P=0.001; LAMP2a r=0.790, P<0.001). Conclusions:After recurrent seizures in developmental rats, the presence of increased expression of multiple molecular chaperone-mediated autophagy, which may positively correlate with apoptosis, may be involved in the process of brain injury.