Raclopride tartrate salt

All experiments were performed with adult male Long-Evans rats (8–10 weeks, 250–350 g) housed in pairs on a 12/12-hr light/dark cycle. Experiments and procedures were conducted according to the German and Swiss national guidelines and approved by the Animal Care Committee of the State of Baden Württemberg (Germany) or the Committee for Animal Experimentation of the Kanton of Zürich (Switzerland). Most chemicals were purchased from Tocris bioscience (Bristol, UK): H-89 hydrochloride (PKA inhibitor), U-73122 (active) and U-73343 (inactive) (PLC inhibitor), m-3m3fbs (PLC agonist), SCH23390 hydrochloride (D1 antagonist), bicuculline methiodide (GABAA antagonist, used for LTP induction). Raclopride tartrate salt (D2 antagonist) was purchased from Sigma-Aldrich Chemie GmbH (Steinheim, Germany).

(−)‐Quinpirole hydrochloride (Sigma‐Aldrich, CAS No: 85798–08–9) and S(−)‐Raclopride (+)‐tartrate salt (Sigma‐Aldrich, CAS No: 98185–20–7) were dissolved in sterile saline. Drug or saline was delivered through an intra‐PVT inserted infusion cannula (O.D., 0.30 mm; I.D., 0.14 mm; length, 4 mm; RWD, Inc.) and infused at a rate of 0.25 μl/min for 2 min (total injection volume: 0.5 μl) by a microinjection pump (KD Scientific Infusion Syringe Pumps). The infusion cannula was designed to protrude 0.50 mm from the tip of the guide cannula and thus penetrate into the PVT. Investigators were blind to the drugs administered.

Raclopride tartrate salt (D2 receptor antagonist) (Sigma Chemical Co., Toluca, Mexico) was dissolved in 0.9% saline solution. The drug was prepared freshly at the appropriate concentration just before administration.