Establishing a Mouse Model of Chlorpromazine-Induced Corneal Trigeminal Denervation.

Purpose: This study aimed to establish a mouse model of chlorpromazine-induced corneal trigeminal denervation (CCTD). Methods: Retrobulbar chlorpromazine injections were administered to 6- to 8-week-old C57BL/6j mice to induce corneal denervation. Additionally, apoptosis was assessed in isolated primary trigeminal ganglion cells after culturing in a conditioned medium containing chlorpromazine. Finally, the success rate of model generation, mortality and complication rates, and model-preparation learning curves were compared between the CCTD model and the electrocoagulation and axotomy models. Results: Chlorpromazine retrobulbar injections resulted in trigeminal denervation, leading to a reduced blink reflex, corneal nerve density, and corneal epithelium thickness. Furthermore, 90% (9/10) of the mice developed epithelial defects, accompanied by increased apoptosis and inhibited proliferation of corneal epithelial cells. In vitro, trigeminal ganglion cell apoptosis increased after culturing in a conditioned medium containing chlorpromazine. Moreover, the CCTD model exhibited a higher success rate, longer survival rate, and lower complication rate compared to the electrocoagulation and axotomy models. Crucially, the learning curve demonstrated that the method used to generate the CCTD model was easy to learn. Conclusions: The CCTD model is a user-friendly mouse model for studying corneal trigeminal denervation that offers a less invasive alternative to existing models. Translational Relevance: The CCTD model serves as a valuable tool for investigating the functional mechanisms of corneal trigeminal nerves and their interactions with corneal cells.

Trigeminal nerve-derived substance P regulates limbal stem cells by the PI3K-AKT pathway.

Trigeminal nerve-derived substance P (SP), a widespread neuropeptide, is known to maintain the corneal epithelial homeostasis and promote the closure of wound healing. Using comprehensive in vivo and in vitro assays and RNA-sequencing analysis, we aimed to unveil the positive effects of SP on the biological characteristics of limbal stem cells (LSCs) and the underlying mechanism. SP enhanced the proliferation and stemness of LSCs in vitro. Correspondingly, it rescued corneal defects, corneal sensitivity, and the expression of LSC-positive markers in a neurotrophic keratopathy (NK) mouse model in vivo. Topical injection of a neurokinin-1 receptor (NK1R) antagonist caused similar pathological changes as in corneal denervated mice and attenuated LSC-positive markers levels. Mechanistically, we revealed that SP regulated LSCs functions by modulating the PI3K-AKT pathway. Our findings showed that the trigeminal nerve regulates LSCs by releasing SP, which may provide new insights into the regulation of LSCs' fate and stem cell therapy.