Fig. 3

Dopamine receptor-dependent effects on IL-1β expression in human microglia. Dopamine receptor transcripts were measured by qPCR. C06 and C20 microglia express DRD1, DRD2, and DRD5 mRNA. A In C06 microglia, there was significantly higher DRD2 expression compared to the D1-like receptors, and in B C20 microglia, there was significantly higher expression of the D1-like receptors compared to DRD2. C C06 and D C20 microglia were treated with dopamine (10^–6 M) or LPS (10 ng/mL) as a positive control for 3 h and examined for IL-1β mRNA. There was no effect in C06 microglia, but in C20 microglia, dopamine significantly increased IL-1β mRNA. E C06 and F C20 microglia were treated with dopamine (10^–6 M) or poly I:C (10 ug/mL) as a positive control for 4 h, then lysates were collected and examined for IL-1β production by AlphaLISA. There was no effect in C06 microglia. However, in C20 microglia dopamine significantly increased IL-1β production. G C06 and H C20 microglia were pretreated with flupentixol (Flux, 10–6 M) or vehicle for 30 min in the presence of absence of 3 h dopamine (DA, 10^–6 M) treatment and examined for IL-1β mRNA. There was no effect of treatment on C06 microglia, but in C20 microglia Flux significantly blocked the DA-mediated increase in IL-1β. Significance was determined by paired t-tests, Wilcoxon tests, Kruskal–Wallis tests, post-hoc with Dunn’s multiple comparisons, and a two-way mixed effects model and post-hoc with Tukey’s multiple comparisons, *p < 0.05, **p < 0.01, ***p < 0.001, and *****p < 0.0001. ND = not detected