Abstract
Abstract: :
Purpose: To investigate the early neuronal responses to optic nerve crush in the lateral geniculate nucleus (LGN) and the retina of rats and their possible roles. Methods: Forty–three Sprague–Dawley rats were used. Unilateral (right eye) optic nerve crush was produced using micro clips (70 gram force) for 30 seconds in 36 rats. C–Jun and c–Fos expression in the retina and LGN were studied with a polyclonal antibody by immunohistochemistry and Western blot at time periods of 2 hours, 1, 3 and 7 days after crush or 1 day after sham operations. Double immunolabelling of c–Fos and c–Jun respectively with calbindin D–28k (CB) were also studied in the LGN. Both eyes and LGNs were examined. Results: After optic nerve crush, c–Jun positive cells were observed in the ipsilateral retinal ganglion cells and all three subdivisions of both LGNs as early as 2h postoperation. At the LGN, c–Fos was observed ipsilaterally in the medial subdivision of ventral LGN and intermediate geniculate nucleus. The c–Fos immunoreactivity was visible after 2h, reached maximum at 1day post injury, then decreased at 3 and 7 days. The time course of c–Jun expression in the LGN was similar with that of c–Fos. Colocalisation of c–Fos and CB was observed ipsilaterally in the medial subdivision of ventral LGN and intermediate geniculate nucleus. The range of colocalisation of c–Fos and CB was from 75% to 83%. The percentage of colocalisation of c–Jun and CB was lower than 15% in both LGNs at all time periods postoperation. Conclusions: Optic nerve crush activates the expressions of immediate early genes in the LGN and the retina. Retino–recipent nucleus driven by intact eye in the LGN is affected after the optic nerve crush. Calbindin D–28k is involved in the transmission of harmful stimulus in the central visual pathway. These results suggest that LGN may possess the activity–dependent plasticity in response to optic nerve injury.
Keywords: neuro-ophthalmology: optic nerve • thalamus/lateral geniculate nucleus • signal transduction