Mk 801

Pexidartinib (PLX3397, MedChemExpress, Cat# HY-16749, USA) was dissolved in 2% dimethyl sulfoxide (DMSO), 0.1% Tween 80, and 5% sulfobutylether-β-cyclodextrin (SBE-β-CD). PLX3397 was administered orally in drinking water at 1 mg/mL (delivering daily doses of approximately 150 mg/kg body weight). Control mice received vehicle solution (2% DMSO/0.1% Tween 80/5% SBE-β-CD/93% water, vol/vol/vol). All mice were habituated to drink the vehicle solution ad libitum for 5 days prior to exposure to the PLX3397 solution. Drinking bottles were filled daily with newly prepared PLX3397 and vehicle solutions. All drinking bottles were manually shaken once a day for a few seconds. Alternatively, PLX3397 was administered (i.p. injection) in mice at a dose of 50 mg/kg (12 h intervals). Minocycline (MedChemExpress, Cat# HY-17412, USA) was dissolved in sterile saline and injected (i.p.) at a dose of 50 mg/kg. The animals were injected twice a day with either Minocycline or saline for 3 consecutive days before behavioral testing. MK-801 (Sigma-Aldrich, USA, Cat# M107) was freshly prepared in sterile saline and injected (i.p.) at a volume of 0.01 mg/mL. MK-801 (0.1 mg/kg body weight) was given to each mouse 30 min before behavioral testing. Control experiments were performed following saline administration. Administration of PLX3397 and Minocycline was stopped 12 h before behavioral testing.

For the detection of autoantibodies against NMDAR, AQP4, and MOG we used live HEK293A cells transfected with the respective complementary DNA, as described previously.^{6 (link),7 (link)} The following cutoff values were used: ≥1:20 for NMDAR antibodies, ≥1:160 for MOG antibodies, and ≥1:20 for AQP4 antibodies.
To prove the specificity of antibody binding, serum samples were preincubated with HEK293A cells expressing NMDAR or nontransfected HEK293A.
One CSF sample was tested for NMDAR antibodies as described above, except CSF was applied undiluted but supplemented with MK-801 (Sigma-Aldrich, St. Louis, MO) and further diluted (1:2, 1:4, etc.) in washing buffer containing MK-801.
NMDAR antibody testing with fixed cell-based assay (CBA) and rat brain immunohistochemistry (IHC) was done as described recently.^{9 (link)}