title: Calibration and standardisation of graded optic nerve injuries in rats.
abstract: OBJECTIVE
  To calibrate and standardise an animal model of graded optic nerve injury (ONI) in rats to facilitate future inter-laboratory data comparisons, focussing on quantification of injury intensity, injury severity, and the correlation between them.
  
  
  METHODS
  A pair of cross-action forceps or a pair of artery clips was used to induce optic nerve (ON) crush injuries. A lever principle and a simplified method were used to measure the crushing force. The simplified method directly measured weights as an external force exerted on the tip of the forceps or clips, which was just sufficient to maintain a gap and was equivalent to the closing (crush) force. The impulse and averaged impulse were explored as physical quantities to compare injury intensities. Graded ONIs were made by crushing the ON for 3, 6, 12, 30 or 60 seconds by the cross-action forceps, or 5, 10 or 15 seconds by the artery clips. The injury severity was evaluated by counting surviving retinal ganglion cell (RGC) through applied FluoroGold to the superior colliculus and lateral geniculate body before ON crush, intact RGC counting by applied FluoroGold after ON crush, and ON axon counting.
  
  
  RESULTS
  Similar results were obtained by the lever principle method and the simplified method. The crushing force of the cross-action forceps and the artery clips was 148.0 gram force (gf) and 32.4 gf, respectively. The graded ONI animal models were successfully created in rats without retinal ischaemia post-trauma. The averaged impulse produced by the artery clips for 15 seconds was equal to that produced by a 3-second crush of the cross-action forceps. The correlation between injury intensity and injury severity was fitted for a power function.
  
  
  CONCLUSIONS
  Our results provide a simplified and effective means to quantify and analyse data from ON crush studies compared with previously reported animal models.
authors: Hou-Bin
authors: HB
authors: Huang
authors: Yi-Xin
authors: YX
authors: Zhang
authors: Shui-Hua
authors: SH
authors: Zhang
authors: Zhi-Zhong
authors: ZZ
authors: Ma
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology; D002138:Calibration; D002452:Cell Count; D004195:Disease Models, Animal; D005260:Female; D005829:Geniculate Bodies / Q000473:pathology; D009409:Nerve Crush / Q000379:methods; D020221:Optic Nerve Injuries / Q000473:pathology; D010784:Photomicrography; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000473:pathology; D012171:Retinal Vessels / Q000473:pathology; D012720:Severity of Illness Index; D013266:Stilbamidines; D013477:Superior Colliculi / Q000473:pathology; D013997:Time Factors; D014795:Visual Pathways / Q000473:pathology
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D013266:Stilbamidines
keywords: Animal model,; ON injuries,; Optic nerve axon,; Rats; Retinal ganglion cell,