Lipopolysaccharide-induced abdominal nociception behavioral model in adult zebrafish (Danio rerio)

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.