Figure 4.

Nasal administration of Hcrt-1 improves social memory in AT mice. The AT subject mice received nasal administration of either vehicle (deionized water, n = 13, a) or Hcrt-1 (0.8 nmol, n = 14, b). The social memory test with a 10 min delay between the completion of sociability and the beginning of social novelty sessions. The AT mice that were treated with vehicle exhibited normal sociability and reproducible social memory deficits (a: for sociability, p < 0.001; for social memory, p = 0.362). The AT subjects that were treated with Hcrt-1 displayed normal sociability, but also showed a distinct shift in their investigation to Stranger 2 from familiarized Stranger 1 (b: for sociability, p < 0.001; for social memory, p < 0.001). Other two measureable social interaction parameters, active time (c and d, p < 0.001) and travel distance (e and f, p = 0.013), also indicated that the Hcrt-treated AT mice improved social recognition memory.