Different effects of dynorphin A on in vitro guinea pig hippocampal CA3 pyramidal cells with various degrees of paired-pulse facilitation.
We investigated the effects of dynorphin A (Dyn A), a heptadecapeptide, on the population spikes of the guinea pig hippocampal CA3 pyramidal neurons, in vitro, using paired-pulse stimulation of the mossy fibers. Dyn A produced facilitatory and inhibitory effects on the population spikes in the preparations with lower and higher degrees of paired-pulse facilitation, respectively. Morphine and D-Ala2, D-Leu5-en-kephalin, mu- and delta-agonist, respectively, predominantly potentiated the population spikes, while kappa-agonists such as U-50, 488H and bremazocine mainly caused an inhibition. These results suggest that Dyn A has two separate (excitatory and inhibitory) effects on the guinea pig hippocampal CA3 neurons through mu-(delta) and kappa-opioid receptors, respectively.
Iwama
T
T
Ishihara
K
K
Satoh
M
M
Takagi
H
H
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology; D004347:Drug Interactions; D004399:Dynorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D009435:Synaptic Transmission / Q000187:drug effects
D001575:Benzomorphans; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D004399:Dynorphins; D009020:Morphine; C027248:bremazocine