Tetramethylpyrazine protects mice retinas against sodium iodate–induced oxidative injury

PURPOSE: To observe the effects of tetramethylpyrazine (TMP) on mice retinas injured by sodium iodate (NaIO(3)). METHODS: Male mice (n = 45) were randomly divided into three groups: the control group (Group C), the NaIO(3)-degenerated group (Group I), and the TMP-treated group (TMP group). The Group I mice were intraperitoneally injected with 35 mg/kg NaIO(3). The Group C mice were injected with similar volumes of PBS. The TMP group mice were intraperitoneally injected with 80 mg/kg TMP starting 24 h after NaIO(3) administration once a day for 14 days. Fundus photography, optical coherence tomography (OCT), electroretinography (ERG), hematoxylin and eosin (H&E) staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, and western blotting were used to assess the effects of TMP on mice retinas at day 3, 7, and 14 after NaIO(3) administration. RESULTS: TMP effectively prevented the decrease in the thicknesses of the retinas and the outer nuclear layer (ONL), and effectively alleviated the functional decline in the retinas after NaIO(3) administration. TMP significantly decreased the number of TUNEL-positive cells in retinas. In addition, TMP rapidly increased the expression of Nrf2 and HO-1 and decreased BAX expression in mice retinas after NaIO(3) injection. CONCLUSIONS: TMP alleviates morphological and functional retinal damage in mice exposed to NaIO(3) and reduces retinal apoptosis.