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Yang Qu, Shaodan Zhang, Ruoxi Li; Oral Administration of Picrorrhizae Extract Ameliorates Retina Damage in Rat Optic Nerve Crush Model. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3265.
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To evaluate the neuronal protective effect and therapeutic mechanisms of Picrorrhizae extract (PRE) in rat optic nerve crush model.
Wistar male rats (250-300 g, China Medical University, Shenyang) were anesthetized with intraperitoneal injection of chloral hydrate (25-30 mg/100g, Sinopharm). Optic nerve was crushed 2mm behind the right eye with angled forceps for 5 sec. After the model was established, PRE (Log No.1202113, Tianjiang Pharmaceutical, Jiangsu) at the dosages of 10mg/100g, 50mg/100g and 100mg/100g was intragastrical given to the rats at eight time points (day 0, 1, 3, 5, 7, 14, 21, 28). Distilled water was intragastrically given to the control rats with (crush group) and without (normal group) crush. In vivo retina thicknesses were measured using OCT (ZEISS Cirrus™ HD-OCT 4000) at day 29, cryosections were then made from enucleated eye and retinal histological structures were observed under light microscope (Leika DM1000).
In normal rats, oral administration of PRE at 50mg/100g and 100mg/100g apparently broke down the normal histological structures of retina, suggesting the toxic effect on the neuronal tissues at these dosages. The retina structure remained intact when 10mg/100g PRE was administrated, at which dosage the therapeutic effect of PRE on optic nerve crush was tested (10mg PRE group). Using OCT, the retinal thickness measured 500μm away from optic papilla was significantly reduced in the crush group (129.98±17.15μm, n=5) compared to that in the normal group (198.50±7.78μm, n=3, p<0.05). Whereas in 10mg PRE group, the retinal thickness was 173.78±14.92μm (n=5), with no statistical difference from that in the normal group (p>0.05). In retina HE cryosections, the counts of retinal ganglion cells, retina thickness normalized by the thickness of outer nuclear layer and thickness of retinal fiber layer were measured. In 10mg PRE group, the values were 38.8±2.17, 3.13±0.14 and 89.6±2.70μm, respectively (n=5), significantly larger than those in the crush group, which were 10.25±1.71, 2.0±0.16 and 40±2.16μm, respectively (n=4, p<0.05). The data did not show statistical difference from those in the normal group, which were 47±1.63, 3.2±0.05 and 110.2±1.71μm, respectively (n=4, p>0.05).
Oral administration of PRE restores retina structure as observed in OCT and histological study, suggesting a therapeutic effect of PRE on optic neuropathy.
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