Fig. 4

Similar activation of the NAc during both spontaneous and chocolate-induced cataplexy-like behavior. Coronal brain slices, including the nucleus accumbens (NAc), A were obtained from five groups of mice. No cataplexy group (n = 4); mice were anesthetized after 10 min of the cataplexy-free period, and the brain was sampled. Spontaneous cataplexy-like behavior group (n = 4); when the mice showed cataplexy-like behavior without chocolate and any other apparent stimulus, they were immediately anesthetized, and the brain was sampled. Chocolate-induced cataplexy group (n = 4); when the mice showed cataplexy-like behavior within 1 min after the chocolate bite, they were immediately anesthetized, and the brain was sampled. In the no cataplexy in the 2MT group (n = 4), mice were anesthetized after 10 min of a cataplexy-free period in a cage with 2MT, and the brain was sampled. In the 2MT-related cataplexy-like behavior group (n = 4), when the mice showed cataplexy-like behavior in a cage with 2MT, they were immediately anesthetized, and the brain was sampled. Photographs in B show typical examples from five groups of the brain. According to our previous method [7], the number of pERK-positive cells was counted in the area indicated by a dashed rectangle (400 × 1000 µm) in the NAc shell. C Statistical results using Sidak's multiple comparison test showed significantly higher numbers of pERK-positive cells in the chocolate-induced and spontaneous cataplexy group than in other groups. There was no significant difference between chocolate-induced and spontaneous cataplexy groups. Each group consists of two females (red dots) and two males (black dots)