アカハライモリ（Cgynops pyrrhogaster）における加速度刺激を無条件刺激とした食物嫌悪条件づけの予備的検討

抄録

The authors have shown that Japanese fire-bellied newts (Cynops pyrrhogaster) exhibit a reduction in consumption of a conditioned stimulus (CS) food after it is paired with an injection of lithium chloride (LiCl). In rats and other animals, food aversion conditioning has also been demonstrated using acceleration stimulation as an unconditioned stimulus (US) paired with a novel food. The present study examined whether Japanese fire-bellied newts could acquire food aversion conditioning by pairing a novel food with orbital stimulation as the US. The newts underwent five conditioning sessions, each followed by a test. The first four sessions involved orbital stimulation at 120 rpm, with variations in duration (15 to 60 minutes), direction (with or without reversal), and inclination (with or without a 13-degree tilt). Across these conditions, the newts showed no reduction in CS food consumption; instead, their intake gradually increased across trials. In contrast, when an injection of LiCl solution was used as the US in the last conditioning session, the newts exhibited a significant reduction in CS consumption. These results suggest that the lack of conditioned food aversion in the orbital stimulation conditions was not attributable to latent inhibition (i.e., reduced conditioning due to prior exposure to the CS). The findings further suggest that Japanese fire-bellied newts may not experience motion sickness in response to acceleration stimulation.