Anesthesia was administered as follows: a mixture of racemic ketamine (100 mg/kg) and xylazine (20 mg/kg) intraperitoneally (ip), pentobarbital (60 mg/kg ip), 2,2,2-tribromoethanol (also known as Avertin; 120 mg/kg ip), α-chloralose (80 mg/kg ip), and ISO (initial induction at 4%, maintained at 1 to 2% for the duration of the experiment). For the α-chloralose regimen, surgery was initially done under 1 to 2% ISO and maintained at 0.5% ISO following CM injection because the drug is technically a hypnotic rather than a general anesthetic. In a separate cohort of mice, dex was given as a supplement to ISO induction at 0.015 mg/kg ip, with a second equal-sized bolus administered just before the 30-min tracer circulation period. ISO was always delivered with 100% oxygen. Depth of anesthesia was determined by the pedal reflex test. If the mouse responded to toe pinch an additional ¹/₁₀ of the initial dosage was given and the tracer experiment was delayed until full unconsciousness was obtained. Directly before CM infusion, the animal received an additional ¹/₁₀ of the initial dosage, and the pedal reflex was tested every 5 to 10 min during the tracer circulation time to ensure proper anesthesia throughout the study. Animals under Avertin anesthesia were most likely to need supplemental dosing. For mechanisms of action of each drug, please see Table 1.

This table provides a summary of how different drugs used in this study modulate neurotransmission. The drug name is listed on the left, potential targets of each drug are listed in the middle, and references for more in-depth descriptions are provided on the right. NMDAR, N-methyl-d-aspartate receptor; 5-HT, 5-hydroxytryptamine; K_2P, two-pore potassium; HCN, hyperpolarization-activated cyclic nucleotide-gated.