HC-030031

Dry eye disease (DED) is characterized by neurosensory abnormalities, complicating the management of ocular pain, and is further worsened by significant ocular inflammation. Although multiple inflammatory pathways contribute to DED, the role of neurogenic inflammation, particularly through transient receptor potential ankyrin-1 (TRPA1) nociceptors, which are expressed in the cornea nerve fibers, remains underexplored. This study investigates the involvement of TRPA1 in ocular pain and neurogenic inflammation in chronic DED. To explore this, multi-unit extracellular recordings were used to monitor ciliary nerve activity in naive mice after exposure to the TRPA1 antagonist (HC-030031). An in vivo DED model was then created by surgically removing the extraorbital and Harderian lacrimal glands in mice. HC-030031 was topically applied twice daily from day 7 to day 21 post-surgery. Corneal sensitivity and integrity were evaluated, followed by immunohistology, flow cytometry, and mRNA expression analyses in the cornea. Electrophysiological recordings showed that while HC-030031 did not affect spontaneous corneal nerve activity, but it significantly reduced responses to thermal, mechanical, and chemical stimuli. Behavioral tests indicated that HC-030031 reversed corneal mechanical hypersensitivity and alleviated ocular discomfort associated with DED. Additionally, it promoted corneal nerve regeneration, decreased substance P, and reduced inflammation in the cornea. Specifically, it lowered immune cell infiltration and the expression of inflammatory genes such as Ccl2 and Il1Β in the cornea. These findings highlight the key role of TRPA1 nociceptors in modulating corneal neurosensory abnormalities and neurogenic inflammation in DED.

In this study a behavioral model of LPS-induced abdominal nociception was developed on adult zebrafish (Danio rerio), aZF. Initially, the toxicity of different LPS concentrations was assessed. The abdominal nociceptive response to the lowest LPS concentration was then analyzed, and the impact of sex on this nociceptive response was evaluated. The behavioral model of abdominal nociception was defined using the antinociceptive effects of morphine and diclofenac sodium. The mechanism of the possible involvement of TRPA1 in LPS-induced abdominal nociception was evaluated using HC-030031. Additionally, was investigated whether naloxone could modulate morphine's antinociceptive effect. The Light & Dark Test was conducted to assess any potential anxiolytic-like effect of LPS. The Open Field Test was performed to evaluate the possible sedative effect/or not of morphine and diclofenac sodium. As a result, the tested LPS endotoxin solutions were not endotoxic against aZF (LC₅₀>0.25 mg/mL). LPS significantly increased the abdominal nociceptive behavior of aZF. Sex did not affect the response profile to the endotoxin. Morphine and diclofenac sodium inhibited abdominal nociception induced by LPS and the effect of morphine was blocked by naloxone. HC-030031 significantly inhibited abdominal nociception induced by LPS. The LPS did not cause an anxiolytic-like effect. Morphine and diclofenac sodium did not affect the locomotion of the animals. The results suggest that aZF can be used as a behavioral model of abdominal nociception induced by LPS endotoxin.