Identification of Behavioral Patterns That Contribute to Emesis through Multiple Linear Regression of Spontaneous Behavior upon Motion Sickness inSuncus Murinus

This is the authors' abstract. We don't add key points for this paper.

Abstract ID 130306 Poster Board 116 Introduction: In humans, motion sickness (MS) is a common but complex syndrome characterized by a cluster of signs and symptoms including cold sweating, facial pallor, drowsiness, hypersalivation, nausea, vomiting and stomach awareness. In the present study, we analyze the distribution of spontaneous behaviors related to vomiting induced by motion in Suncus murinus. The aim is to identify behavioral patterns that characterize MS in this species to underpin future studies of drugs capable of reducing behaviors that may be indicative of emesis and perhaps 'nausea'. Methods: Male Suncus murinus weighing 55–90 g was used. They were accustomed to the testing arena for 10 h before collecting 30 min of baseline data. They were then exposed to provocative motion (1 Hz, 4-cm horizontal displacement) for 30 min, followed by another 30 min where they were stationary. JWatcher software (version 1.0) was used to record the following behaviors: vomiting, sniffing, licking, scratching, chin-on-the-floor, exploring, digging, circling, resting, lying flat, face washing, spraying legs, gaping, and playing/eating with bedding. Behaviors of 11 Suncus murinus were recorded for 30 min before, during, and after motion using JWatcher software while behaviors of 180 Suncus murinus were only recorded for 30min during motion. Stepwise multiple linear regression analyses (removal criterion p = 0.15), conducted using Jamovi Statistical Software, were employed to identify the correlation relationships between behaviors and MS. Episodes of emesis were considered as a variable, while other behaviors were regarded as factors. 24 Suncus murinus were prescreened then allocated by Latin square to test the effect of diphenhydramine on behaviors and emesis induced by motion by the analyses described above. Vehicle (saline) or diphenhydramine (3–30 mg/kg) were injected 30 min before motion. Results: Compared with the period before motion, the resting time increased significantly (p < 0.05), while sniffing, licking, scratching, digging, circling, and gaping episodes decreased significantly (p < 0.05) during motion (n = 11). Furthermore, the lying flat duration significantly increased (p < 0.05), and sniffing, chin on the floor, digging, circling, and 'splaying' leg episodes significantly decreased (p < 0.05) after motion (n = 11). The 10 behaviors affected by motion were used as variables for multiple linear regression analyses (n = 180). A stepwise multiple regression (removal criterion p = 0.15) indicated that the MS symptom score could be represented (adjusted multiple r-squared = 0.308) as a weighted sum of the number of chin-on-the-floor (coefficient: 0.410), circling (coefficient: 0.311), gaping (coefficient: -0.805), and resting time (coefficient: 0.499), plus a constant term (7.609). This behavioral scoring system was used to test the effect of diphenhydramine, which significantly antagonized emesis at 30 mg/kg (P < 0.05). Diphenhydramine at 30 mg/kg also significantly reduced the index from 14.23 ± 1.17 to 10.35 ± 0.36 (P < 0.05). Conclusion: An MS symptom score was derived and validated by examining the effects of diphenhydramine on motion-induced changes of spontaneous behaviors. The approach provides new insights into the mechanism of MS and emesis in Suncus murinus. Acknowledgement: This study is supported by RGC grant 14108021.