STZ treatment induced apoptosis of retinal cells and effect of up-regulation of calcitonin gene related peptide in rats

The apoptosis of the retinal cells was confined to the GCL, in which CGRP was normally located. A significant increase in the apoptosis ratio (P < 0.05) was observed in the STZ treated animals and high glucose incubated retina, with reductions of CGRP. The pre-treatment with capsaicin effectively up-regulated CGRP and its encoding mRNA and attenuated the cell apoptosis and caspase-3 activity in the retina. The increases of the cell apoptosis in the retina may be related to the down-regulation of endogenous CGRP in diabetes. Capsaicin may attenuate the apoptosis of the retina cells at early times of diabetes, via up-regulation of CGRP.