Naloxone-like actions of MIF-1 do not require the presence of the pituitary

Abba J. Kastin, Cheryl Nissen, James E. Zadina, Andrew V. Schally, Rudolph H. Ehrensing

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The actions of peripherally administered MIF-1 (Pro-Leu-Gly-NH2) and naloxone in blocking the effects of morphine in the tail-flick test were measured across a wide range of five doses in hypophysectomized and intact mice. The presence of the pituitary gland failed to influence the response to MIF-1 or naloxone. Both hypophysectomized and intact mice were significantly affected by these two compounds at doses of 0.01, 0.1, 1.0, and 10.0 mg/kg IP. The greatest effect of MIF-1 occurred at 100 mg/kg, but naloxone was lethal at this dose. Preliminary experiments with other tests showed that at 10 mg/kg, naloxone, but not MIF-1, was effective in preventing the Straub-tail reflex and in precipitating withdrawal-jumping in mice implanted with morphine pellets. Only minimal activity was shown by MIF-1 in preventing blockade of electrically induced contractions of the guinea pig ileum by morphine. Neither compound was active in the frog-righting test. In summary, the results emphasize the differential actions of MIF-1 as an opiate antagonist and demonstrate that the pituitary is not required for their mediation.

Original languageEnglish (US)
Pages (from-to)907-912
Number of pages6
JournalPharmacology, Biochemistry and Behavior
Issue number6
StatePublished - Dec 1980
Externally publishedYes


  • Analgesia
  • Frog righting
  • Guinea pig ileum
  • MIF-1
  • Naloxone
  • Opiate
  • Peptide
  • Pituitary
  • Straub tail
  • Tail-flick
  • Withdrawal

ASJC Scopus subject areas

  • Biochemistry
  • Behavioral Neuroscience
  • Pharmacology


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