3.6 Synaptic plasticity was impaired in both PrL and IL in ICV-STZ rats and reversed by 1-MT.
It has been acknowledged that neuroinflammation can influence both neurogenesis and neuroplasticity. Golgi staining can visually observe the dendritic spines, thereby reflecting changes in synaptic plasticity and function (Figure 9A). Additionally, BDNF is a dimeric protein used to delineate neuroplasticity. In the PrL, the main effects of ICV-STZ were observed in the total spine density (F(1,20)=55.46), mushroom type (F(1,20)=37.50) and levels of BDNF (F(1,20)=11.73); the main effects of 1-MT treatment were observed in the total spine density (F(1,20)=39.21), mushroom type (F(1,20)=10.36) and levels of BDNF (F(1,20)=19.42). A significant interaction between ICV-STZ and 1-MT treatment was observed in the total spine density (F(1,20)=26.53), thin type (F(1,20)=4.376), filopodia type (F(1,20)=4.543), mushroom type (F(1,20)=11.06) and levels of BDNF (F(1,20)=23.22). For IL, the main effects of ICV-STZ were observed in the total spine density (F(1,20)=16.10), mushroom type (F(1,20)=5.068) and levels of BDNF (F(1,20)=9.407); the main effects of 1-MT treatment were observed in the total spine density (F(1,20)=27.29), mushroom type (F(1,20)=21.27), stubby type (F(1,20)=10.09) and levels of BDNF (F(1,20)=7.88). A significant interaction between the ICV-STZ and 1-MT treatment was observed in the total spine density (F(1,20)=32.82), mushroom type (F(1,20)=21.57), stubby type (F(1,20)=18.78) and levels of BDNF (F(1,20)=5.012). The post hoc test showed that ICV-STZ rats displayed a drastic decrease in dendritic spine density and the proportion of mushroom in both PrL and IL, and these abnormalities were reversed by intra-PrL or IL injection of 1-MT (Figure 9B-G). In another aspect, the proportion of thin and filopodia was increased significantly in the PrL by ICV-STZ, intra-PrL injection of 1-MT reversed the increase of thin, but the increase of filopodia was slightly and not significantly blocked by 1-MT (Figure 9D). In contrast, the proportion of stubby was increased significantly in the IL by ICV-STZ, which was reversed by intra-IL injection of 1-MT (Figure 9G). The expression of BDNF in the PrL and IL were both remarkably decreased in ICV-STZ rats, and intra-PrL and IL administration of 1-MT can reverse the decreased BDNF levels induced by ICV-STZ (Figure 9H-K).