Enkephalin but not morphine modulates the motor activity in the frog spinal cord in vitro.
In the isolated frog spinal cord, methionine-enkephalin (ME, up to 3 X 10(-5) M) hyperpolarized the resting ventral and dorsal root potentials. These hyperpolarizations remained even under Ca2+-free conditions. ME depressed the fast component of the electrically stimulated spinal reflex and enlarged the following depolarizing component. Morphine (10(-4) M) had no apparent ME-like effects. ME may directly and indirectly affect the motoneuron and modulate the spinal motor activity in the frog spinal cord.
Suzuki
T
T
Oka
J
J
Nagano
N
N
Fukuda
H
H
D000818:Animals; D004399:Dynorphins / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D004743:Enkephalin, Leucine / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology; D004745:Enkephalins / Q000494:pharmacology*; D006651:Histocytochemistry; D066298:In Vitro Techniques; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology; D011892:Rana catesbeiana; D012018:Reflex / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects*
D004745:Enkephalins; D009270:Naloxone; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D004399:Dynorphins; D009020:Morphine