Traumatic injury induced homer-1a gene expression in cultured cortical neurons of rat.

The Homer proteins belong to one of the newly found postsynaptic density protein families. As an immediately early gene, the homer-1a is dynamically expressed and is upregulated by synaptic activity. The homer-1b/c is constitutively expressed and there is no change of gene expression with neuronal activity. In this study, we investigated whether a traumatic injury might regulate the homer-1a expression in cultured cortical neurons of rat. After 7 days in vitro cultivation, the rat fetus cortical neurons were divided into control and injured groups. Then, a traumatic injury was performed on a cortical neuronal culture using a punch device that consisted of 28 stainless steel blades joined together, these produced parallel cuts of 1.2 mm that were uniformly distributed through the cell layer. The lactate dehydrogenase level of the neuronal cultures medium was evaluated and the expression patterns of homer-1a, homer-1b/c were analyzed with the method of RT-PCR and Western blot at different times after the injury (10, 30 min, 1, 3, 6, 12, 24, 72 h). It was shown that there was no expression of homer-1a in the control group, but homer-1a was upregulated in the period of 10 min to 72 h after the traumatic injury. The homer-1b/c was clearly observed in the control group, but there was no change in its expression after traumatic stimulation. It was concluded that traumatic stimulation could induce the homer-1a gene expression, dynamically expressed homer-1a and constitutively expressed homer-1b/c might modulate the distribution and function of group I metabotropic glutamate receptors.