Tetramethylpyrazine inhibits retinal cell death in oxygen-induced retinopathy

Abstract

Objective To observe the inhibitory effect of tetramethylpyrazine(TMP)on apoptosis of retinal neurons in oxygen-induced retinopathy(OIR).Methods 48 C57BL/6 mice were randomly divided into normal control group(n=18),OIR control group(n=18)and OIR TMP group(n=12).The mice of normal control group were raised in room air.From the postnatal day 7(P7),mice of the other two groups mice of OIR TMP group received intraperitoneal injection of TMP(200 mg/kg)once a day from P12 to P16.meanwhile the mice of normal control group and OIR control group were iniected with the same volume of normal saline containing of 0.1% DMSO.At P12,P14 and P17,the morphologic changes in retinal avascular zone and the number of retinal apoptotic cell were observed by HE staining and TUNEL assay.Results At P1 2.there were a few of chromatin condensation and pycnic nuclei in the inner nuclear layer (INL)of OIR control group.At P14,a great quantity(OIR control group)or some(OID TMP treated group)chromatin condensation and pycnic nuclei in the central INL were observed.At P17,the thickness of INL,inner plexiform layer(IPL)and outer plexiform layer(OPL)in the OIR control group were reduced;the thickness of INL,IPL and OPL in the OIR TMP group weas thinner than those in the normal control group and thicker than those in the OIR control group.At P12,the TUNEL-positive cells in the OIR control group was 6 times of the normal eontrol group(F=587.217,P＜0.001).At P14,the difference of TUNEL-positive cells in three groups was significant(F=587.217,P＜0.001);the TUNEL-positive cells in the OIR control group was 28 times of the normal control group(t=49.813,P＜0.001);the TUNEL-positive cells in the OIR TMP group has reduced 50% compared with the OIR controI group(t=42.434,P＜0.00 1).At P17,there was no significant difference in TUNEL-positive cells among the three groups (F=587.217,P>0.05).Conclusions TMP can inhibit apoptosis of retinal cells in OIR significantly. Key words: Retinal diseases/drug therapy; Tetramethylpyrazine/therapeutic use; Apoptosis/drug effects; Animal experimentation