Effects of SB203580 on Homer1a expression in hippocampus and learning-memory after diffuse brain injury in rats

Objective To explore the effects of SB203580(a MAPK inhibitor) on the expression of Homer1a in hippocampus and learning-memory after diffuse brain injury in rats. Method Male Sprague-Dawlley rats were divided randomly into three groups: control group, diffuse brain injury(DBI)group and DBI+ SB203580 group (peritoneal injection, 0.01 μg/kg). Morphological changes of neuronal cells were observed by electron microscope and the expression of Homer1a and phosphorylated p38MAPK was detected by immunohistochemistry and learning and memory functions were performed with Morris water maze (MWM). Results Compared with control group, ultrastructure of neuronal cells and synapses were significantly.The levels of phosphorylated p38MAPK(76.98±16.64, 2.28±0.40, P<0.05) and Homer1a (62.96±12.74, 1.28±0.10, P<0.05)respectively were increased after injury impaired.MWM test showed that the escaping latency was prolonged((74.64± 8.96)s, (24.96±4.98)s, P<0.05) and the frequency of crossing the platform was decreased(4.48±1.12, 12.65±2.36, P<0.05). Compared with the model group, SB203580 decreased ultrastructure impariment in neuronal cells and synapses and decreased phosphorylated p38MAPK expression(54.82±12.48, 76.98±16.64, P<0.05) and increased Homer1a expression(54.82±12.48, 76.98±16.64, P<0.05). MWM test showed that the escaping latency was shorten ((46.72±6.58)s, (74.64±8.96)s, P<0.05), and the frequency of crossing the platform was increased(7.56±1.20, 4.48±1.12, P<0.05). Conclusion SB203580 improves the learning-memory recovery after DBI, which is related to inhibition of p38MAPK activation and increasing Homer1a expression. Key words: Diffuse brain injury; Homer1a; Mitogen-activated protein kinases; learning-memory