BACKGROUND: The visual pathway have 6 parts, involving optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiation and cortical striatum area. Corresponding changes may be found in these 6 parts following optic nerve injury. At present, studies mainly focus on optic nerve and retina, but studies on lateral geniculate body are few.OBJECTIVE: To prepare models of acute optic nerve injury for observing the changes of neurons in lateral geniculate body, expression of neurofilament protein at different time after injury and cell apoptosis under the optical microscope, and for investigating the changes of neurons in lateral geniculate body following acute optic nerve injury.DESIGN: Completely randomized grouping design, controlled animal experiment.SETTING: Department of Neurosurgery, General Hospital of Jinan Military Area Command of Chinese PLA.MATERIALS: Twenty-eight adult healthy cats of either gender and common grade, weighing from 2.0 to 3.5 kg, were provided by the Animal Experimental Center of Fudan University. The involved cats were divided into 2 groups according to table of random digit: normal control group (n =3) and model group (n =25). Injury 6 hours, 1, 3, 7 and 14 days five time points were set in model group for later observation, 5 cats at each time point. TUNEL kit (Bohringer-Mannheim company)and NF200& Mr 68 000 mouse monoclonal antibody (NeoMarkers Company) were used in this experiment.METHODS: This experiment was carried out in the Department of Neurosurgery, General Hospital of Jinan Military Area Command of Chinese PLA between June 2004 and June 2005. ① The cats of model group were developed into cat models of acute intracranial optic nerve injury as follows: The anesthetized cats were placed in lateral position. By imitating operation to human, pterion approach was used. An incision was made at the joint line between outer canthus and tragus, and deepened along cranial base until white optic nerve via optic nerve pore and further to brain tissue. Optic nerve about 3 mm was liberated and occluded by noninvasive vascular clamp for 20 s. After removal of noninvasive vascular clamp, the area compressed by optic nerve was hollowed and narrowed, but non-fractured. Skull was closed when haemorrhage was not found. Bilateral pupillary size, direct and indirect light reflect were observed. Operative side pupil was enlarged as compared with opposite side, direct light reflect disappeared and indirect light reflect existed,which indicated that the models were successful. Animals of control group were not modeled .② The animals in the control group and model group were sacrificed before and 6 hours, 1, 3, 7 and 14 days after modeling respectively. Lateral geniculate body sample was taken and performed haematoxylin & eosin staining. Immunohistochemical staining showed lateral geniculate body neurofilament protein expression,and a comparison of immunohistochemial staining results was made between experimental group and control group. Terminal deoxynucleo-tidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) was used to label apoptotic cells in lateral geniculate body.MAIN OUTCOME MEASURES: Neuronal morphological change, neurofilament protein expression and cell apoptosis in lateral geniculate body following acute optic nerve injury.RESULTS: Twenty-eight involved cats entered the final analysis. ① Histological observation results: In the control group, cell processes were obviously found, which were few or shortening in the model group. ②Neuronal neurofilament protein expression: Cells in lateral geniculate body in the control group and at 6 hours after injury presented clear strip-shaped staining, and those at 7 and 14 days presented irregular distribution without layers and obviously decreasing staining intensity. The positive rate of neurofilament protein in lateral geniculate body in control group and 6 hours, 1, 3, 7 and 14 days after injury was ( 10.22±0.42) %, (10.03±0.24) %, (9.94±0.14) %, (9.98±0.22) %, (8.18±0.34) % and (6.37±0.18)%,respectively. Positive ate of neurofilament protein in control group, at 6 hours, 1 or 3 days after injury was significantly different from that at 7 days after injury (P ＜ 0.05); Positive rate of neurofilament protein in control group, at 6 hours, 1, 3 or 7 days after injury was significantly different from that at 14 days after injury (P ＜ 0.05). It indicated that neuronal injury in lateral geniculate body was not obvious within short term after optic nerve injury, but obvious at 7 days after injury and progressively aggravated until at 14 days after injury. ③ Neuronal apoptosis: TUNEL staining showed that neuronal apoptosis in lateral geniculate body appeared at 7 days after injury, and a lot of neuronal apoptosis in lateral geniculate body was found at 14 days after injury. It indicated that neuronal injury in lateral geniculate body was related to apoptosis.CONCLUSION: In short term after optic nerve injury (within 7 days), nerve injury of lateral geniculate body is not obvious, then, it will aggravate with the elongation of injury time. The occurrence of neuronal injury of lateral geniculate body is related to the apoptosis of nerve cells.