2025/09/28 by David Ares‐Suárez, Almudena Íñigo‐Portugués, Enrique Velasco +9 · 1 voice
Medicine · Biochemistry, Genetics and Molecular Biology · Neuroscience · #Ocular Surface and Contact Lens #Connexins and lens biology #Circadian rhythm and melatonin
paper · pdf · doi:10.1111/bph.70189
openalex publication_date 2025/09/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
BACKGROUND AND PURPOSE: The functional organization of corneal cold nerve endings, critical structures in maintaining the ocular surface, remains poorly understood. Here, the photoisomerizable small-molecule diethylamine-azobenzene-quaternary ammonium (DENAQ) was used to photomodulate activity of cold-sensing nerve terminals in control and chronic tear-deficient corneas. Furthermore, DENAQ was used for in vivo photochemical regulation of the thermally induced blink reflex. EXPERIMENTAL APPROACH: Extracellular nerve terminal impulse activity was recorded on cold terminals in excised corneas of naïve and tear-deficient guinea pigs pre-incubated with DENAQ. Pulses of light at a wavelength of 460 nm were delivered to the perfused corneas. The thermally induced blink reflex was assessed using orbicularis oculi electromyography in anaesthetised rats after topical administration of DENAQ to the eye under blue light and darkness conditions. KEY RESULTS: Exposure to blue light robustly reduced spontaneous activity of both naïve and tear-deficient cold nerve terminals pre-incubated with DENAQ, while cold-evoked responses remained unaffected. Pre-incubation of excised corneas with DENAQ, along with pharmacological P2X receptor antagonists, prevented the DENAQ-mediated photoreduction of the cold nerve terminal spontaneous activity. In addition, blue light increased cold-evoked reflex blink in eyes pre-treated with DENAQ. CONCLUSION AND IMPLICATIONS: ) channel activity. Furthermore, the cold-evoked blink reflex is modulated by light in DENAQ-treated eyes. Chemical photoswitches like DENAQ might be potential new treatments for ocular discomfort and pain in dry eye disease.