Dynamic changes in adenosine monophosphate-activated protein kinase in neonatal rats with hypoxic ischemic encephalopathy

Abstract

Objective To determine the dynamic changes in adenosine monophosphate-activated protein kinase (AMPK) in neurons of neonatal rats suffering from hypoxic ischemic brain injury. Methods Twenty-four-hour old and seven-day old neonatal rats were used in this study. A classic primary cortical neuron oxygen glucose deprivation (OGD) model and neonatal rat hypoxic ischemic encephalopathy (HIE) model were employed. Lactic dehydrogenase (LDH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were used to evaluate neuron viability and damage. The expression of phosphorylated adenosine monophosphate-activated protein kinase (P-AMPK), phosphorylated activated protein kinase (P-Akt) and Cleaved Caspase-3 in neurons and brain tissue was measured by Western blot at different time points after OGD or HIE. The Student-t test was used for statistical analysis. Results (1) Compared with the control group, LDH levels at 2, 4, 8 and 24 h after OGD were higher (all P<0.05) and optical absorption levels of MTT were lower (all P<0.05). (2) Levels of P-AMPK in the OGD group were higher than those in the control group, and showed a time-dependent increase at 30 min and 2, 4, 8 and 24 h (all P<0.05). The expression levels of P-AMPK in the HIE group were higher than those in the control group (0.345±0.038, 0.387±0.112 and 0.618±0.075 at 1, 3 and 7 days after HIE, and 0.132±0.032 in the control group, all P<0.05). (3) The levels of P-Akt increased above the control levels at 30 min (0.991±0.134 vs 0.304±0.050), reached a maximum level at 2 h (1.183±0.107), and then gradually declined, whereas the levels of Cleaved Caspase-3 started to increase at 30 min, and remained elevated at 24 h (all P<0.05). Conclusion Following hypoxic ischemic brain damage, the expression of P-AMPK is significantly increased in both in vivo and in vitro studies in a time-dependent manner. Key words: Hypoxia-ischemia, brain; AMP-activated protein kinases; Animals, newborn; Rats