3.1 ICV-STZ could induce depressive- and anxiety-like behaviors.
Our previous studies demonstrated that ICV-STZ induced sleep disorder(Cui, Song et al., 2018) and memory impairments(Zhao, Cui et al., 2021) in rats on day 14. However, the non-cognitive behaviors in the early stage were still unknown. The results of FST exhibited a significant increase in immobility time, indicating helplessness in the ICV-STZ rats (t(10) =9.026, Figure 2A). Meanwhile, the ICV-STZ rats exhibited a significant decrease in sucrose preference in the SPT (t(10) =5.809, Figure 2B), representing anhedonia-like behavior. And a significant prolongation in latency time to feed in the NSFT ( t(10) =4.730, Figure 2C) was found in ICV-STZ rats. Food consumption after NSFT was no difference across the groups excluded the ingestion bias (Figure 2D). Still, ICV-STZ rats showed a significant decrease in time in center in the OFT, representing anxiety-like behavior in certain aspects( t(10) =5.580, Figure 2E). Locomotor activity did not reveal significant differences between the vehicle and ICV-STZ rats (Figure 2F). In the NORT, the discrimination ratio was found no significant difference in ICV-STZ rats compared with the vehicle rats, reflecting there were no impairments in recognition memory and discrimination ability under the treatment of ICV-STZ (Figure 2G). In addition, the Western blot image (Figure 2H) and quantitative analysis did not reveal a significant difference in the expression of Aβ (Figure 2I), Tau (Figure 2J), pTauser199 (Figure 2K) and the ratio of pTauser199/Tau (Figure 2L) in the mPFC of ICV-STZ rats.