Expression of immediate early gene c-fos in the lateral geniculate nucleus of rats with optic nerve injury

Abstract

To investigate the early neuronal response to optic nerve crush in the lateral geniculate nucleus (LGN) of rats. Unilateral optic nerve crush injury was produced in Sprague-Dawley rats by using micro clips of 70 gram forces. The rats were sacrificed at time periods of 2 hours, 1, 3, 7 and 14 days after crush. C-fos expression was studied with a polyclonal antibody by immunohistochemistry and Western blot. Double immunolabelling of c-fos and calbindin D-28k was also studied by confocal laser scanning microscope. Expression of c-fos was observed ipslaterally in the medial subdivision of ventral LGN and intermediate geniculate nucleus (IGN). The numbers of c-fos positive cells were visible at 2 h post injury and peaked at 1 d. Thereafter, the expression decreased at 3 d, 7 d and still a few was observed at 14 d. C-fos immunoreactivity was scarcely observed in the dorsal LGN and in the LGN of control rats. Expression of calbindin D-28k was mainly observed in the medial subdivision of ventral LGN and IGN. 75% approximately 83% c-fos positive cells were also calbindin D-28k immunopositive. Expression of c-fos was induced in calbindin D-28k positive relay neurons in the ipslaterally medial subdivision of ventral LGN and IGN. They may play some important roles during the pathologic process of acute optic nerve injury.