Potentiation of the dorsal immobility response following intrastriatal injections of enkephalins.
The effects of bilateral intrastriatal injections (1.0 microgram/side) of leucine5- and methionine5-enkephalins and their related nonopiate fragments upon three measures of immobility over a time course were investigated. Both leucine5-enkephalin and des-Tyr1-leucine-enkephalin potentiated the duration of the dorsal immobility response (DIR) 15 min postinjection and over a 1-h time course. On the other hand, methionine5-enkephalin and des-Tyr1-methionine-enkephalin potentiated the duration of the DIR at 5 and 15 min. These enkephalins and their fragments had no effect upon vertical cling and bar catalepsy. In a second study, an SC injection of 4 mg/kg naloxone 15 min prior to the central injections blocked the potentiation of the DIR effects of the enkephalins.
Meyer
M E
ME
Department of Psychology, University of Florida, Gainesville 32611.
van Hartesveldt
C
C
Cottrell
G A
GA
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002375:Catalepsy / Q000139:chemically induced; D003342:Corpus Striatum / Q000033:anatomy & histology; D004745:Enkephalins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D012018:Reflex / Q000187:drug effects
D004745:Enkephalins; D009270:Naloxone