Inhibition by morphine of the cardiovascular and behavioral responses evoked by centrally administered substance P in conscious rats

K. Itoi, N. Jost, C. Tschöpe, J. Culman, E. Badoer, Th Unger

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

The effect of endogenous opioid receptor stimulation on the central cardiovascular and behavioral actions of substance P (SP) was examined in conscious rats. SP (55 pmol) injected intracerebroventricularly (i.c.v.) elicited increases in mean arterial pressure, heart rate, and stereotyped behavioral activation such as exploring and grooming, which were considered to be parts of the cardiovascular defense reaction. Intravenous (i.v.) pretreatment with morphine (2.5 and 5.0 mg/kg) attenuated the cardiovascular and behavioral responses produced by SP i.c.v. dose-dependently. The i.v. pretreatment with naloxone (10 mg/kg) had no effect on the central SP-induced response. Presser responses elicited by i.c.v. injection of corticotropin-releasing factor or angiotensin II were also attenuated by pretreatment with i.v. morphine (5.0 mg/kg). Our results showed that endogenous opioid receptor stimulation antagonizes the central cardiovascular and behavioral actions of SP. Morphine may not influence the primary site of action of SP but does influence the central neural pathway which conveys the SP-induced sympathetic activation signal.

Original languageEnglish
Pages (from-to)181-187
Number of pages7
JournalNeuropharmacology
Volume33
Issue number2
DOIs
Publication statusPublished - 1994 Feb

Keywords

  • Defense reaction
  • angiotensin II
  • blood pressure
  • corticotropin-releasing factor
  • heart rate
  • naloxone

ASJC Scopus subject areas

  • Pharmacology
  • Cellular and Molecular Neuroscience

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