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. Author manuscript; available in PMC: 2016 Jun 15.
Published in final edited form as: Mol Cell Endocrinol. 2015 Mar 25;408:90–98. doi: 10.1016/j.mce.2015.03.014

Figure 2. Relating nanomolar and micromolar concentration-based effects of TSPO ligands.

Figure 2

MA-10 Leydig cells were incubated with 0–100 µM of the isoquinaline carboxamide TSPO ligand PK 11195 for 2h. At the end of incubation, media was collected for analysis of steroid production by RIA, or cellular viability was assessed by MTT assay. PK 11195 began to significantly stimulate steroid production at nanomolar concentrations, and continued rising though high micromolar concentrations. However, high levels (>50µM) of PK 11195 were cytotoxic, without affecting steroid production, suggesting that such stimulation was nonspecific, and not due to stimulation of TSPO but rather to rupturing of mitochondrial membranes.