Xylazine promotes axonal regeneration in the crushed optic nerve of adult rats.

Xylazine, an alpha-2 adrenergic agonist, activates the endogenous trophic factors and neuronal survival signaling. Here, we tested the regenerative effect of xylazine on damaged optic nerve axons in adult rats. After optic nerve crush, xylazine was intraperitoneally injected into three groups of rats: a single administration immediately after the crush, intermittent administration, and daily administration. On day 14, the regenerated axons were quantitatively evaluated by anterograde labeling. Everyday administration but neither single nor intermittent administration markedly increased the number of labeled axons beyond the crush site, with upregulation of growth-associated protein-43 in the ganglion cell layer and the regenerated axons. It was concluded that xylazine promotes axonal regeneration in damaged optic nerves of adult rats.