CCI, a rodent model of TBI increases PBR28suv
Representative PET images are displayed in Fig. 1AB. The time-activity curves of the ipsilateral hemisphere shows that the uptake (SUV) was maximum around 30 s for CCI and 10 s for Sham. When comparing the PBR28suv (ipsilateral) over time, there was a significant increase in SUV in injured rats in comparison to sham (Fig. 1C, p < 0.0001).
The time-activity curve of the whole brain shows that the uptake (SUV) was maximum around 30 s for CCI and 10 s for Sham. PBR28suv of total brain of sham animals is significantly lower in than the PBR28suv of CCI animals (p < 0.0001, Fig. 1C). From 50 s to 1050s, CCI animals have a higher SUV than sham. [11C]PBR28 uptake is relatively stable over the course of the imaging.
CCI results in an increase in amoeboid-shaped microglia in the ipsilateral corpus callosum
Controlled cortical impact resulted in a significant increase in amoeboid-shaped IBA1 positive cells in the corpus callosum. Specifically, there was an increase in the amoeboid-shaped microglia ipsilateral to the injury (Fig. 2B, p = 0.029, n = 4, 102 ± 13) when compared to sham (n = 4, 3.75 ± 4.2), but not contralateral to the injury [CCI: n = 5, 10.8 ± 13 vs Sham: n = 4, 5.00 ± 3.9 (Fig. 2B, p = 0.13)]. Interestingly, there were no differences in the number of ramified microglia on either the ipsilateral [Fig. 2A, CCI: n = 5, 274 ± 90 vs Sham: n = 4, 136 ± 12 (p = 0.11)] or contralateral hemisphere [Fig. 2B, CCI: n = 4, 142 ± 6.8 vs Sham: n = 4, 134 ± 18 (p = 0.34)].
CCI results in an increase in amoeboid-shaped microglia ipsilateral to the injury in the dentate gyrus
Controlled cortical impact resulted in a significant increase in amoeboid-shaped IBA1 positive cells in the ipsilateral dentate gyrus only [Fig. 3B, CCI: n = 5, 91.2 ± 97 vs Sham: n = 4, 4.25 ± 2.2 (p = 0.016)] There was no increase in the number of amoeboid-shaped IBA1 positive cells contralateral to the injury [Fig. 3B, CCI: n = 5, 10.8 ± 13 vs Sham: n = 4, 5.00 ± 3.9 (p = 0.63)] when compared to sham. There were no differences in the number of ramified microglia in the ipsilateral [Fig. 3A, CCI: n = 5.00, 158 ± 95 vs Sham: n = 4, 135 ± 12 (p = 0.60)] or contralateral hemisphere [Fig. 3A, CCI: n = 5, 143 ± 47 vs Sham: n = 4, 134 ± 18 (p = 0.99)] when compared to sham.
CCI results in an increase in amoeboid-shaped microglia in the medial ipsilateral thalamus
Controlled cortical impact resulted in a significant increase in amoeboid-shaped IBA1 positive cells in the medial ipsilateral thalamus when compared to sham [Fig. 4B, CCI:n = 5, 50.2 ± 21 vs Sham: n = 4, 9.00 ± 7.1 (p = 0.016)]. There were no differences in the contralateral side when compared to sham [Fig. 4B, CCI :n = 4, 8.50 ± 15 vs Sham: n = 3, 1.00 ± 0.0 (p = 0.99)] Additionally, there were no differences in the number of ramified IBA1positive cells ipsilaterally [Fig. 4A, CCI: n = 5, 38.2 ± 13 vs Sham: n = 4, 28.0 ± 5.7 (p = 0.34)] and contralaterally [Fig. 4A, CCI: n = 4, 21.5 ± 13 vs Sham: n = 4, 36.0 ± 8.4 (p = 0.17)] when compared to sham.
CCI results in an increase in amoeboid-shaped microglia in the lateral ipsilateral thalamus
Similar to the medial thalamus, CCI resulted in a significant increase in amoeboid-shaped IBA1 positive cells in the lateral ipsilateral thalamus when compared to sham [Fig. 5B, CCI: n = 5, 69.6 ± 34 vs Sham: n = 4, 7.00 ± 7.2 (p = 0.016)]. There were no differences in the contralateral side when compared to sham [Fig. 5B, CCI: n = 5, 13.0 ± 14 vs Sham: n = 4, 2.00 ± 2.7 (p = 0.11)]. Also, there were no differences in the number of ramified microglia on either the ipsilateral [Fig. 5A, CCI: n = 5, 35.4 ± 16 vs Sham: n = 4, 24.0 ± 7.8 (p = 0.31)] or contralateral hemisphere [Fig. 5A, CCI: n = 5, 27.8 ± 17 vs Sham: n = 4, 22.5 ± 17 (p = 0.37)] when compared to sham.
CCI results in PBR co-staining with IBA1 and not GFAP
We stained one section from each animal (ipsilateral) to examine the loci of PBR in astrocytes and microglia. Qualitatively we did not observe any co-staining of GFAP and PBR (Fig. 6A-D), however there was considerable co-staining of PBR and IBA1, specifically in the amoeboid shaped cells (Fig. 6E-H).