Figure 1. [3H]DAA1106 shows lower KD values in rats with TBI when compared with [3H](R)-PK11195.
Saturation filtration binding experiments were performed in the cortex of rats with CCI on the side ipsilateral and the side contralateral to injury using [3H]DAA1106 (n=3) (black symbols) and [3H](R)-PK11195 (n=3) (open symbols). The Bmax (fmols/mg), reflective of the total number of binding sites and the KD (nM) reflective of the binding affinity of the ligands to PBR was calculated using PRISM software.
A and B, Representative saturation binding curves with [3H]DAA1106 (A) and [3H]-(R)PK11195 (B) from rats with CCI in the cortex ipsilateral to (squares) and contralateral (circles) to the contusion.
C, The Bmax (fmols/mg), reflective of the total number of binding sites was significantly higher in the area ipsilateral to the contusion compared with the area contralateral to the contusion with both [3H]DAA1106 (black bars, p = 0.0109) and [3H](R)-PK11195 (clear bars, p = 0.0488). Bmax with [3H]DAA1106 and [3H](R)-PK11195 did not differ significantly in either the ipsilateral (p = 0.0742) or the contralateral (p = 0.1331) side to the injury.
D, The KD (nM), reflective of the ligand binding affinity was not different between the ipsilateral and the contralateral regions with either [3H]DAA1106 (p = 0.1835) or [3H]-(R)PK11195 (p = 0.6664). However, the KD with [3H]DAA1106 was significantly lower than with [3H]-(R)PK11195 in both ipsillateral (p = 0.0400) and contralateral (p = 0.0125) regions.
E, The ratio of Bmax/KD, representative of the binding potential of each ligand was calculated with each ligand in the ipsilateral and contralateral regions. Bmax/KD ratio was significantly higher with [3H]DAA1106 on the ipsilateral compared to the contralateral side (p = 0.0395). Bmax/KD ratio was significantly higher with [3H]DAA1106 compared to [3H]-(R)PK11195 on the ipsilateral side (p = 0.0094). Data was analyzed using student’s t test, **p<0.01, *p<0.05.