Figure 4. RNA interference downregulates astrocyte TAAR1 protein levels and intracellular cAMP in response to METH and β-PEA.

Human astrocytes were MOCK-, siCON- and siTAAR1-transfected and plated for 48 hr followed by 24 hr of METH (500 μM) treatment. Cells were fixed and probed for TAAR1 (green) and GFAP (red). MOCK- (A) and siCON- (C) transfected astrocytes showed TAAR1 protein expression with and without METH treatment at 24 hr. METH (500 μM) treated MOCK- and siCON-transfected astrocytes demonstrated similar levels of TAAR1 protein (B and D). As expected siTAAR1-transfected astrocytes demonstrated reduced TAAR1 expression (E and F). Intracellular cAMP levels were quantified in MOCK-, siCON- and siTAAR1-transfected astrocytes. siTAAR1-transfected astrocytes showed significantly reduced METH and β-PEA-induced intracellular cAMP (G, ***p<0.001, n=4, independent astrocyte donors).