3.4 Differential responses of PrL and IL to microglial
alterations induced by ICV-STZ.
Since neuroinflammation is regulated by glial cells in the central
nervous system, we further observed the alteration of microglia in the
PrL and IL to examine the potential target of 1-MT. Iba1 was considered
as the microglia marker. As shown in Figure 5, the main effects of 1-MT
treatment were observed in the Iba1-positive cell number
(F(1,20)=5.118), levels of Iba1 protein
(F(1,20)=11.20) and 3-HK (F(1,20)=11.97)
from PrL. The post hoc test revealed that there was no significant
difference in the fluorescent images of immunostaining for Iba1 (Figure
5A) and the count of microglia (Figure 5B) in the PrL of ICV-STZ rats
administered saline or 1-MT. Similarly, the expression of Iba1 (Figure
5C) and microglial morphology in the PrL (Figure 5D-F) were not
influenced by either ICV-STZ or 1-MT. Levels of 3-HK (Figure 5G) in the
PrL was insignificant difference across the groups, although intra-PrL
injection of 1-MT induced an increasing trend. In the IL, the main
effects of ICV-STZ were observed in the Iba1-positive cell number
(F(1,20)=8.092) and levels of Iba1 protein
(F(1,20)=7.915); the main effects of 1-MT treatment were
observed in the Iba1-positive cell branches
(F(1,20)=8.960). Moreover, a significant interaction
between ICV-STZ and 1-MT treatment was observed in the Iba1-positive
cell number (F(1,20)=8.092), levels of Iba1 protein
(F(1,20)=6.103), Iba1-positive cell branches
(F(1,20)=37.13), Iba1-positive cell end-points
(F(1,20)=7.035) and levels of 3-HK
(F(1,20)=6.667). Fluorescent images of immunostaining
for Iba1 (Figure 6A) and the count of Iba1-positive cells number (Figure
6B) presented that the number of microglia in the IL was significantly
increased by ICV-STZ, while intra-IL injection of 1-MT recovered the
density of Iba1-positive cells to normal. Western blot analysis also
revealed that the expression of Iba1 in the IL was significantly
increased by ICV-STZ, and reversed by intra-IL injection of 1-MT (Figure
6C). Subsequently, the analysis of morphological features in microglia
(Figure 6D-F) indicated that ICV-STZ remarkably decreased the branch
number (Figure 6E) and end-point number (Figure 6F) of Iba1-positive
cells in the IL, and intra-IL injection of 1-MT prevented these
decreases. On the other hand, the levels of 3-HK increased with
microglia activation in the IL, and this increase was reversed by
intra-IL injection of 1-MT (Figure 6G).