Masato Fukui, Takayuki Nakagawa, Masabumi Minami and Masamichi Satoh*
Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
*Corresponding author. FAX: +81-75-753-4586, E-mail: msatoh@pharm.kyoto-u.ac.jp
Abstract: The present study examined what kind of receptors are involved in the antinociception produced by intracerebroventricular (i.c.v.) administration of a,b-methylene-ATP using antagonists at adrenergic, serotonin or opioid receptors. Antinociceptive effect of a,b-methylene-ATP (10 nmol/rat) was significantly attenuated by subcutaneous pretreatment with propranolol and naloxone, but not phentolamine or methysergide, at a dose of 10 mg/kg. I.c.v. pretreatment with propranolol (100 nmol/rat), butoxamine (100 nmol/rat), ICI-118,551 (100 nmol/rat) and naloxone (30 nmol/rat) significantly attenuated the antinociceptive effect of a,b-methylene-ATP. However, i.c.v. pretreatment with atenolol (100 nmol/rat), naltrindole (30 nmol/rat) or nor-binaltorphimine (30 nmol/rat) did not show any significant effects. These results suggest that supraspinal b2-adrenergic and m-opioid receptors are involved in the antinociceptive effect of i.c.v. administered a,b-methylene-ATP.
Keywords: a,b-Methylene-ATP, Antinociception, b2-Adrenoceptor, m-Opioid receptor, Intracerebroventricular
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