[Selectivity of opioid peptide effects on excitability and various sensory inputs in LPl1 and PPl1 command neurons participating in defensive behavior of the snail Helix lucorum].
Opioid peptides effects on neural membrane as well as neural responses evoked by sensory stimuli with different modality and site of application, were investigated in L-RPII command neurones of defensive behaviour of semi-intact preparation in the land snail Helix lucorum. Met-enkephalin (10 uM) application onto the snail CNS increases membrane excitability and produces facilitation of neural responses evoked by quinine solution (0.5%) application onto snail head and depression of reactions evoked by tactile stimulation of the head. Met-enkephalin in dose of 0.1 uM initiates only a depression of neural responses evoked by tactile stimulation of the head. Leu-enkephalin (10 uM) application suppresses neural reactions evoked by tactile stimulation of the head. Membrane excitability and neural responses evoked by quinine application onto the snail head do not change after leu-enkephalin administration. Effects appear 10-20 min after initiation of the peptide application. Initial neural responses were observed 15-30 min after CNS washing with Ringer solution. In addition, facilitation of neural responses evoked by chemical stimulation of the snail head was found 30-50 min after leu-enkephalin washing. Peptides do not change neural responses evoked by tactile stimulation of the snail foot. Neural effects of peptides were prevented by simultaneous naloxon administration (50 uM). Experimental results show selective opioid peptides' effects on excitability and plasticity of L-RPII neural inputs with site- and modality-specifics.
Nikitin
V P
VP
Research Institute of Normal Physiology, Russian Acad. Med. Sci., Moscow, 103009, B. Nikitskaya, 6, Russia.
Kozyrev
S A
SA
Shevelkin
A V
AV
D000200:Action Potentials; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D004743:Enkephalin, Leucine / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology; D004924:Escape Reaction / Q000187:drug effects / Q000502:physiology*; D005121:Extremities; D006257:Head; D006372:Helix, Snails; D009473:Neuronal Plasticity / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D018847:Opioid Peptides / Q000494:pharmacology / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology
D018847:Opioid Peptides; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine