Abnormal expression of leucine-rich repeat transmembrane neuronal protein 2 in temporal lobe tissue of rats induced by lithium-pilocarpine

Objective Leucine-rich repeat transmembrane neuronal protein 2(LRRTM2) localizes to excitatory glutamatergic synapses, and triggers the formation of excitatory synapses. This study aims to investigate the expression of LRRTM2 protein in the temporal lobe tissue of SD rats induced by lithium-pilocarpine, and explore its roles in epilepsy. Methods Fifty-six Sprague-Dawley (SD) rats were induced by lithium-pilocarpine and randomly divided into 6 h, 24 h, 72 h, 7 d, 14 d, 30 d and 60 d subgroups. Eight SD rats were treated with normal saline instead of pilocarpine as controls. Expression of LRRTM2 protein was accessed by immunohistochemistry, immunofluorescence and Western blot analysis. Results LRRTM2 protein mainly expressed in neurons of temporal lobe, gradually decreased in acute phase, and then up-regulated in latent and chronic periods. The immunohistochemistry A values in model rats from 6 h, 24 h, 72 h, 7 d, 14 d, 30 d and 60 d subgroups were 0.286±0.012, 0.227±0.008, 0.425±0.015, 0.509±0.019, 0.579±0.018, 0.488±0.018 and 0.566±0.014, respectively, compared to 0.330±0.016 in control group ( t= 3.965, 11.987, 9.131, 14.121, 20.452, 12.929 and 22.786, all P< 0.05). Gray value ratios of LRRTM2/β-actin in different groups of model rats were 0.0354±0.0043, 0.0174±0.0026, 0.0685±0.0064, 0.0957±0.0125, 0.1044±0.0103, 0.0910±0.0108, and 0.1012±0.0063, respectively, which were significant differences from control group (0.0471±0.0033, t= 4.354, 14.191, 5.989, 7.541, 10.565, 7.730 and 15.316, all P<0.05). Conclusions LRRTM2 protein gradually increases in the neurons of temporal lobe of SD rats treated by lithium-pilocarpine in silence and chronic phases, which indicates that it may play an important role in epileptogenesis. Key words: Epilepsy;  temporal lobe; Neural cell adhesion molecules; Pilocarpine; Rats