Synergistic Effects of Adenosine Antagonists

The following substances were used: DPCPX (8–cyclopentyl–1,3–dipropylxanthine, Sigma–Aldrich, Poznań, Poland), istradefylline (KW–6002, (E)–8–(3,4–dimethoxystyryl)– 1,3–diethyl–7–methylxanthine, Sigma–Aldrich, Poznań, Poland), magnesium hydroaspartate (Farmapol, Poznań, Poland), and zinc hydroaspartate (Farmapol, Poznań, Poland). DPCPX (1 mg/kg) and istradefylline (0.5 mg/kg) were suspended in a 0.9% saline with Tween 80 (1%) (POCH, Gliwice, Poland), whereas magnesium and zinc hydroaspartate (10 mg/kg and 2.5 mg/kg, calculated as pure magnesium or zinc ions, respectively) were dissolved in 0.9% saline. DPCPX and magnesium hydroaspartate were injected intraperitoneally (i.p.) 30 min, while istradefylline was administered orally (p.o.) and zinc hydroaspartate i.p. 60 min before behavioural testing. Animals from control group were given 0.9% saline. All liquid dosage forms were prepared immediately prior to the experiments and they were administered in a volume of 0.01 mL/g.
The treatment schedules and subtherapeutic doses of DPCPX, Mg²⁺ and Zn²⁺ were chosen on the basis of our previous projects [30 (link),31 (link)], whereas of istradefylline were selected on the basis of literature data [105 (link)] and then confirmed in preliminary studies carried out in our laboratory.