Inhibition of retrograde axoplasmic transport in rat optic nerve by increased IOP in vitro.
Horseradish peroxidase (HRP) injected into one lateral geniculate nucleus of hooded rats, is taken up by terminals of the optic nerve and transported retrogradely towards the opposite retina. Four hours after injection, a small portion of HRP has reached the retina. After excision of the bulb and optic nerve and another 4 hours of in vitro transport during which different levels of intraocular pressure (IOP) were set, more HRP accumulated in the retina. The amounts entering in vitro at IOPs of 35 and 50 mmHg were 29% and 76% less, respectively, than at 20 mmHg. The lamina cribrosa of the rat strain used was studied by scanning electron microscopy. It consisted of only one complete laminar sheet, a fact that minimizes optic nerve fiber strangulation by laminar shearing in raised IOP. Thus, moderately increased IOP can inhibit fast retrograde transport of HRP in the optic nerve of the rat by direct mechanical pressure, and does not involve either the blood circulation or a multilayered structure of the lamina cribrosa.
D000818:Animals; D001370:Axonal Transport; D006735:Horseradish Peroxidase; D007429:Intraocular Pressure; D008297:Male; D008855:Microscopy, Electron, Scanning; D009900:Optic Nerve / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D012160:Retina / Q000378:metabolism
D006735:Horseradish Peroxidase