Positive memory increases cataplexy-like behaviors in narcolepsy mice as revealed using conditioned place preference test

• Published in: BMC neuroscience 2022-12, Vol.23 (1), p.82-82, Article 82
• Main Authors: Yoshida, Mayuko, Yamamoto, Koki, Kuwaki, Tomoyuki
• Format: Article
• Language: English
• Subjects: Animals; Cataplexy; Cataplexy behavior; Development and progression; Disease Models, Animal; Extracellular signal-regulated kinase; Female; Humans; Medical research; Medicine, Experimental; Memory; Mice; Narcolepsy; Neurons - metabolism; Nucleus accumbens; Nucleus Accumbens - metabolism; Orexin neurons; Orexins - metabolism; Positive emotion; Positive emotions; Psychological aspects
• ISSN: 1471-2202; 1471-2202
• DOI: 10.1186/s12868-022-00772-2

Cataplexy is a loss of muscle tone that can lead to postural collapse, disturbing the daily life of narcolepsy patients; it is often triggered by positive emotions such as laughter in human patients. Narcolepsy model mice also show cataplexy, and its incidence increases in response to positive emotion-inducing stimuli such as chocolate and female courtship. Although such observation indicates a positive emotion-related nature of cataplexy in narcolepsy mice, they also show cataplexy without any apparent triggering stimulus ~ (spontaneous cataplexy). Therefore, we hypothesized that some spontaneous cataplexy in narcoleptic mice might indicate the remembering of happy moments. To test our hypothesis, we did a conditioned place preference test on orexin/hypocretin neuron-ablated (ORX-AB) mice, one of the animal models of human narcolepsy, and counted the number of cataplexy-like behaviors. ORX-AB mice successfully remembered the chocolate-associated chamber, and the number of cataplexy-like behaviors significantly increased in the chocolate-associated chamber but not in the control chamber. In addition, ORX-AB mice remembered the aversive odor-associated chamber and avoided entering without affecting the number of cataplexy-like behaviors. Finally, similar activation of the nucleus accumbens, a positive emotion-related nucleus, was observed during both spontaneous and chocolate-induced cataplexy behaviors. These results support our hypothesis and will promote the usefulness of a narcolepsy mice model in emotion research and serve as a basis for a better understanding of cataplexy in narcolepsy patients.