Abstract
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 language | English (US) |
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Pages (from-to) | 907-912 |
Number of pages | 6 |
Journal | Pharmacology, Biochemistry and Behavior |
Volume | 13 |
Issue number | 6 |
DOIs | |
State | Published - Dec 1980 |
Externally published | Yes |
Keywords
- 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