β pea

The drug MDMA was dissolved in physiological saline (in a volume of 2 ml/kg) and administered at doses of 0.5, 2.5, and 5 mg/kg. Morphine (ICN Hungary Plc.) was also dissolved in physiological saline (in a volume of 2 ml/kg) and administered at a dose of 1 mg/kg 30 min before the social interaction assay. GBR‐12909 (Sigma) was dissolved in physiological saline (in a volume of 5 ml/kg) and administered at doses of 1, 3, and 10 mg/kg. All the drugs were administered by subcutaneous (s.c.) injection in the flank region 30 min prior to the behavioral observations. In the coadministration experiment, MDMA and GBR‐12909 were administered to the rats in the two flank regions within a short period of time 30 min prior to the observations. DA‐3,4‐[7,8‐3H(N)], with a specific activity of 60 Ci/mmol, and choline chloride [methyl‐3H], with a specific activity of 80 Ci/mmol, were purchased from American Radiolabeled Chemicals (ARC). β‐PEA was obtained from Sigma. All the other chemicals were obtained from Sigma.

Deuterated water (D₂O) 99.97 atom% of deuterium and 3-(trimethylsilyl)-propionic-2,2,3,3-d₄ acid sodium salt (TSP) were purchased from Euriso-Top (Saclay, France). HPLC-PDA chemical standards, n-hexadecane, HIS, SPM, SPD, PUT, (β-PEA), CAD, TYM and 1,7-diaminoheptane were purchased from Sigma-Aldrich (Milan, Italy). Methanol (HPLC-grade), chloroform (HPLC-grade), ethanol (analytical-grade), perchloric acid (70%), acetone (analytical-grade), acetonitrile (HPLC-grade) were obtained from Carlo Erba Reagenti (Milan, Italy). Double-distilled water was obtained using a Millipore Milli-Q Plus water treatment system (Millipore Bedford Corp., Bedford, MA, USA). Sodium carbonate (Na₂CO₃; 99.999% purity), Folin-Ciocalteu’s phenol reagent, tannic acid (Ph. Eur. purity) and aluminium chloride hexahydrate (AlCl₃ × 6 H₂O; Ph. Eur. purity) were purchased from Merck (Darmstadt, Germany).
Cannabinoids reference standards in methanol CBDV (1 mg/mL), CBG (1 mg/mL), CBD (1 mg/mL), CBN (1 mg/mL), (–)-Δ⁹-THC (0.1 mg/mL) and CBC (1 mg/mL) with purity ≥99%, were purchased from Cerilliant Corporation (Round Rock, TX, USA). For mobile phase, gradient grade water (H₂O) and acetonitrile (ACN) were purchased from Sigma Aldrich (St. Louis, MO, USA) as well as trifluoroacetic acid (TFA) and analytical grade ethanol used for the extraction procedure. All solvents were further filtered on a 0.2 μm filter.

The drugs used were the following: Klamin^® extract (kindly supplied by Nutrigea Research s.r.l., Borgo Maggiore, Republic of San Marino), TTX (Alomone Labs, Jerusalem, Israel), EPPTB (N-(3-Ethoxy-phenyl)-4-pyrrolidin-1-yl-3-trifluoromethyl-benzamide) (Hoffmann-La Roche, Monza, IT, Italy), β-PEA (β-phenylethylamine), L-NAME, 5-HT (Serotonin), methysergide (Sigma-Aldrich, Milano, IT, Italy). All the drugs were dissolved in distilled water. Klamin^® extract was dissolved in 0.5 mL water, and then sonicated (twice for 60 s) immediately prior to add to the bath. Chemicals were prepared as stock solution, which were diluted with Krebs solution on the experiment day.