Tohoku J. Exp. Med., 2003, 201 (1)

Pharmacological Mechanism in Slip-Down
Behavior of Mice

YUTAKA MASUDA, MINORU SUZUKI,¹ TAKAUBU TAKEMURA,¹ JUNYA SUGAWARA,¹ NAXIN GUO,²
YANG LIU,² YOSHIHIKIO KAWARADA,² TETSUO SHIMIZU¹ and TOSHIHIRO SUGIYAMA²

Psychosomatic Division, ¹Department of Neuropsychiatry, ²Department of Biochemistry, Akita University School of Medicine, Akita 010-8543

Slip-down from a raised platform was previously found in mice treated with morphine, and this behavior was also recognized in mice treated with a monoamine releaser methamphetamine. Pharmacological examination on the slip-down indicated that the behavior was induced by receptor stimulations by D₂ agonist PPHT and 5HT-2 agonist DOI. In mice treated with PPHT, antagonists of D₁, α₂, 5HT-2 and opioid mu and kappa suppressed the behavior. In mice treated with DOI, antagonists of D₁, α₂, 5HT-1A, 5HT-3 and opioid mu and delta suppressed the behavior. These present findings suggest that the slip-down was mainly induced by opioid mu receptor activity regulated with monoamine activities. When the slip-down is considered as an anxious behavior, it may be also suggested that the anxiety induced by 5-HT activities furthermore stimulated the behavior via the other opioid receptor activities.

keywords —— slip-down behavior; mice; anxiety; opioid receptor; neurotransmitter activities

© 2003 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2003, 201, 23-27

Address for reprints : Yutaka Masuda, Psychosomatic Division, Department of Neuropsychiatry, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.