Hirofumi Koda1, Yoshiaki Yokoo2, Nobuya Matsumoto2,
Yoshihide Suwa1, Hirotatsu Fukazawa3,
Hitoshi Ishida3, Kuniro Tsuji3, Haruo Nukaya3
and Kinya Kuriyama4
1Products Safety & Alcohol Science Laboratory, Suntory Limited,
1 - 1 - 1, Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618 - 8503, Japan
2Technical Development Department, Suntory Limited, 5 - 2 - 5,
Yamazaki, Shimamoto-cho, Mishima-gun, Osaka 618 - 0001, Japan
3Department of Medicinal Chemistry of Natural Product, School
of Pharmaceutical Science, University of Shizuoka,
52 - 1, Yada, Shizuoka 422 - 8526, Japan
4Kyoto Prefectural University of Medicine, Hirokoji, Kawaramachi-tori,
Kamigyou-ku, Kyoto 602 - 8566, Japan
Abstract: We examined the effect of N-methyltyramine (NMT)
on α2-adrenoceptor. NMT (10-8 -
10-3 M) inhibited the binding of [3H]p-aminoclonidine
to α2-adrenoceptor dose-dependently. However, the IC50
value for NMT (5.53×10-6 M) was higher than that for RX821002,
an α2-adrenoceptor antagonist (1.07×10-8 M). RX821002
(5 mg/kg, i.p.) inhibited hypermotility induced by scopolamine (8 mg/kg,
s.c.) in male ddY mice. NMT (20 or 100 mg/kg, i.p.) was found to have a
dose-dependent inhibitory effect similar to that of RX821002. These findings
indicate that NMT has the properties of an α2-adrenoceptor antagonist.
However, the affinity of NMT for α2-adrenoceptor is weaker than
that of RX821002.
Keywords: N-Methyltyramine, α2-Adrenoceptor, Scopolamine