Potent depressor action of leumorphin, a κ-opioia agonist, in conscious rats

Hiroshi Itoh, Kazuwa Nakao, Takayuki Yamada, Narito Morii, Shozo Shiono, Makoto Sakamoto, Akira Sugawara, Yoshihiko Saito, Masashi Mukoyama, Hiroshi Arai, Hiroo Imura

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


To investigate the role of leumorphin, a κ-opioid agonist derived from proenkephalin B (neoendorphin/dynorphin precursor) in the central cardiovascular control, the effects of intracerebroventricular (ICV) administration of leumorphin on basal blood pressure and angiotensin II (AH)-stimulated pressor response were examined in conscious unrestrained rats. The ICV injection of 0.06 and 0.6 nmol of leumorphin caused a significant decrease in basal blood pressure (Δ mean arterial pressure (MAP): − 6.5 ± 2.7 and − 7.2 ± 1.7 mm Hg, respectively). The ICV injection of AII (0.1 nmol) elicited a pressor response (Δ MAP: 21.4 ±1.1 mm Hg). This pressor response was significantly reduced by the simultaneous administration of leumorphin, and furthermore, the blood pressure was lowered below the basal level. These depressor actions of leumorphin were partially antagonized by the preadmin-istration of naloxone, an opiate antagonist. These results together with our previous works on the potent inhibitory actions of leumorphin on drinking and vasopressin secretion suggest the possible involvement of leumorphin in the central regulation of blood pressure and body fluid homeostasis.

Original languageEnglish
Pages (from-to)256-261
Number of pages6
JournalAmerican journal of hypertension
Issue number3
Publication statusPublished - 1988 Jul
Externally publishedYes


  • Angiotensin II
  • Blood pressure
  • Drinking
  • Leumorphin
  • Opioid peptides
  • Proenkephalin B
  • Vasopressin

ASJC Scopus subject areas

  • Internal Medicine


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