ATPase activities and Ca2+/calmodulin alterations in hippocampi of rats with PTSD-like behaviors

AIM: To explore the pathophysiological bases in the pathogenesis of the lasting emotional behavioral disorders following posttraumatic stress disorder(PTSD). METHODS: 240 male Wistar rats were divided randomly into 3 groups. Group SE(n =96) for rats with PTSD-like behavior by constant pulsating current of 100 μA with intratrain frequencies of 16 Hz, pulsating duration of 1 ms, train duration of 10 s and interstimulus interval of 7 min for 5 days with 8 times per day. Group CE(n =96) for control with electrode implanted in hippocampus without stimulation, and Group NC(n =48) for normal control. The activities of Na⁺-K⁺-ATPase and Ca²⁺ -ATPase, levels of intracellular calcium and free calmodulin(CaM), and the total CaM expression were detected in hippocampi of experimental rats. RESULTS: The activities of Na⁺-K⁺-ATPase and Ca²⁺ -ATPase in mitochondria of hippocampal cells in Group SE rats were significantly decreased at 48 h and 72 h after the last stimulation, respectively. The intracellular free calcium levels were increased, and the mean channel fluorescence of intracellular free CaM decreased remarkably at 72 h poststimulation, while the expression of total CaM was significantly elevated at 48 h after the last stimulation in hippocampi of Group SE rats. CONCLUSION: The lasting increased levels of intracellular free calcium and expression of Ca²⁺ -CaM in hippocampus, as well as the dysfunction of Na⁺-K⁺ pump and Ca²⁺ -ATPase in mitochondria may play important roles in the long-term neuropsychological sequelae in PTSD.