Facilitatory and Inhibitory Effects of Harmaline on the Tryptophan- Induced 5-Hydroxytryptamine Syndrome and Body Temperature Changes in Pargyline-Pretreated Rats

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Author(s)

    • MATSUMOTO Kinzo
    • Division of Pharmacology, Research Institute for Wakan- Yaku (Oriental Medicines), Toyama Medical and Pharmaceutical University
    • MURAKAMI Yukihisa
    • Division of Pharmacology, Research Institute for Wakan- Yaku (Oriental Medicines), Toyama Medical and Pharmaceutical University
    • WATANABE Hiroshi
    • Division of Pharmacology, Research Institute for Wakan- Yaku (Oriental Medicines), Toyama Medical and Pharmaceutical University

Abstract

The effects of harmaline on tryptophan-induced 5-hydroxytryptamine (5-HT) syndrome and body temperature changes in pargyline-pretreated rats were investigated. When administered i.p. 60 min after pargyline treatment (50 mg/kg, i.p.), tryptophan, at 100 mg/kg but not 10 mg/kg, induced the 5-HT syndrome. Tryptophan at 100 mg/kg also produced hypothermia followed by hyperthermia in pargyline-pretreated rats. Administration of harmaline (10 mg/kg, i.p.) 30 min after pargyline not only potentiated the 100 mg/kg tryptophan-induced 5-HT syndrome and body temperature changes, but also produced the syndrome following administration of 10 mg/kg tryptophan in pargyline-pretreated rats. In contrast, when administered 30 min before pargyline, 10 mg/kg harmaline completely suppressed the syndrome and body temperature changes caused by 100 mg/kg tryptophan. Tryptophan (100 mg/kg, i.p.) administration significantly increased 5-HT levels and decreased 5-hydroxyindole acetic acid levels and 5-HT turnover in the brain of pargyline-pretreated rats. Harmaline administration 30 min after pargyline did not significantly affect the tryptophan-induced changes in 5-HT Ievels and 5-HT turnover, whereas when administered 30 min before pargyline, harmaline significantly blocked the effect of tryptophan. These results suggest that mechanisms underlying the inhibitory action of harmaline on the tryptophan-induced 5-HT syndrome and body temperature changes in pargyline-pretreated rats differ from those by which harmaline potentiates the effects of tryptophan.

Journal

  • The Japanese Journal of Pharmacology

    The Japanese Journal of Pharmacology 72(1), 39-47, 1996-09-01

    The Japanese Pharmacological Society

References:  33

Codes

  • NII Article ID (NAID)
    10008675603
  • NII NACSIS-CAT ID (NCID)
    AA00691188
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    00215198
  • Data Source
    CJP  J-STAGE 
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