Tetrodotoxin citrate ttx

Drugs used were in the following final concentrations: 20 μM N-Methyl-DL-aspartic acid (NMA Sigma M2137 – discontinued, 10 μM NMDA M3262 equivalent), 40 μM serotonin creatinine sulfate monohydrate (5-HT, Sigma H7752), 50 µM dihydro-β-erythroidine hydrobromide (DHβE, Tocris 2349), 10 μM mecamylamine hydrochloride (MLA, Tocris 2843), 10 μM CNQX disodium salt (Tocris 1045), 1 μM strychnine hydrochloride (Sigma S8753), and 10 μM picrotoxin (Sigma P1675), 500 nM tetrodotoxin citrate (TTX, Cayman Chemicals 14964).

All recordings were made in open, whole cell configuration in voltage and current clamp mode. Signals were acquired using Multiclamp 700B amplifier and Axon Digidata 1440 (Axon Instruments, San Jose, CA, USA). All recordings occurred in carbogenated RaCSF at 32°C. Drugs were perfused (3 mL min^–1) over the slice in RaCSF. These included dopamine hydrochloride (10, 30 and 100 μm; H8502; Sigma, St Louis, MO, USA), capromorelin (10 nm; CP‐424391; Pfizer, New York, NY, USA), serotonin hydrochloride (5‐HT; 5 μm; H9523; Sigma) and α‐MS maleate salt (α‐ΜS; 5 μm; M110; Sigma). Resulting changes in current (pA) were recorded with V_Holding at −60 mV. In experiments assessing postsynaptic effects of dopamine, tetrodotoxin citrate (TTX; 1 or 3 μm; 14964; Cayman Chemical, Ann Arbor, MI, USA) application occurred 5 min prior to dopamine. Neurons with an access resistance >25 ΜΩ were excluded, as were neurons with more than 50 pA leak current. Under voltage clamp conditions, access resistance change was monitored during the recording and neurons were excluded if access resistance changed >20%. Under current clamp conditions, bridge balance and pipette neutralisation compensation were performed.