The effects of methionine-enkephalin and its related metabolites upon the duration of the dorsal immobility response in rats.
The effects of SC injections of methionine-enkephalin (Met1-5-Enk) and its N-terminal and C-terminal fragments upon the duration of the dorsal immobility response (DIR) over a 60-min time course were investigated. Experiment 1 analyzed the effects of various dosages (0.00-100.0 micrograms/kg) on DIR resulting in a potentiation of the duration in a dose-time course function. The effects of various fragments of Met1-5-Enk (10.0 micrograms/kg) from the N-terminal in Experiment 2 and from the C-terminal in Experiment 3 on the DIR resulted in the potentiation of the duration with the Met2-5-Enk and Met1-3-Enk fragments. All other fragments were not significant. The results were discussed in reference to the processing and metabolism of Met1-5-Enk.
Meyer
M E
ME
Department of Psychology, University of Florida, Gainesville 32611.
D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D013997:Time Factors
D004744:Enkephalin, Methionine