Ly379268

Picrotoxin and QX-314 were purchased from Sigma. LY379268, LY395756, and LY341495 were purchased from Tocris Bioscience. VU6001192 and VU0469942 were generously provided by the Vanderbilt Center for Neuroscience Drug Discovery (Vanderbilt University, Nashville, TN).

N,N,-dimethyltryptamine fumarate (DMT), and N,N-diisopropyltryptamine HCl (DiPT) were provided by the National Institute on Drug Abuse. LY379268, LY341495, SB242084 were received from Tocris. DOI was purchased from Sigma-Aldrich. MDL100907 was synthesized by Drs. Kejun Cheng and Kenner Rice at NIH. DMT, DiPT and DOI were dissolved in 0.9% saline. LY379268 (0.01-2.5 mg/kg) and LY341495 (0.5-2.5 mg/kg) were dissolved in deionized water with sodium hydroxide. SB242084 (0.5-5 mg/kg) was dissolved in Tween80 and deionized water and MDL100907 (0.01-1 mg/kg) was dissolved in saline and HCl. All drugs were administered i.p. in a volume of 1 ml/kg.

VU6001966 and VU0650786 were administered via intraperitoneal (i.p.) injections (10 μL/g 10% v/v Tween 80 vehicle) 45 minutes prior to sacrifice for electrophysiology, the tail suspension test, and the forced swim test; and 24 hours prior to the sucrose preference test. After NAM administration, mice were isolated in a disposable cardboard bucket or remained in their home cages for electrophysiology and behavioral experiments, respectively. Mice were habituated to injections for 2-3 days prior to experimentation. Doses were selected based on published pharmacokinetic analyses to achieve unbound brain concentrations approximately 3-fold higher than each NAM’s IC₅₀ (Bollinger et al., 2017 (link); Engers et al., 2015 (link)). Salvinorin B (SALB) was administered via subcutaneous (s.c.) injection (1 μL/g 100% DMSO vehicle) 10 minutes prior to behavioral experiments. LY379268, LY341495, and LY395756 were purchased from Tocris. SALB was purchased from HelloBio. VU6001966, VU0650786, and MRK-8-29 were synthesized in-house.

LY379268 ((1R,4R,5S,6R)-4-Amino-2-oxabicyclo[3.1.0]hexane-4,6-dicarboxylic acid, Tocris, Bristol, UK) and MPPG ((RS)-α-Methyl-4-phosphonophenylglycine, Sigma-Aldrich, St. Louis, USA) were freshly dissolved in sterile saline on the day of infusion. On the test day, obturators were removed and LY379268 (0.3 or 1.0 μg/side), MPPG (0.12 or 0.5 μg/side) or vehicle at a volume of 0.5 μl was delivered at a flow rate of 0.5 μl/min using 10 μl Hamilton syringes driven by a syringe pump (Harvard apparatus, South Natick, MA, USA). Injectors were left in place for an additional minute to allow diffusion. Next, the obturators were reinserted and the rats were placed in the self-administration chamber, and after 15 minutes the session began. The intracranial doses of LY379268 and MPPG were based on our previous studies (Counotte et al., 2011a (link)). At the end of all experiments (see subsequent sections) the rats were overdosed with pentobarbital and perfused transcardially with 100 ml saline, followed by 250 ml 4% paraformaldehyde in 0.1% sodium phophate buffer. Brains were removed and post fixed for 1 h at room temperature in the same fixative and stored in 30% sucrose plus 0.01% sodium azide. Next, the brains were sectioned, and stained with cresyl violet to verify anatomical placement of the cannulae.

all chemicals were obtained from Sigma, Co., Inc. (St Louis, MO), except YM-254890 (Focus Biomolecules) and LY 379268 (Tocris Bioscience).