CCKB-receptor activation augments the long-term potentiation in guinea pig hippocampal slices
| Autor: | Kazuo Kawasaki, Mitsuru Yasui |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Agonist
Male medicine.medical_specialty Time Factors medicine.drug_class Guinea Pigs Long-Term Potentiation Stimulation Cholecystokinin receptor Hippocampus Sincalide chemistry.chemical_compound Internal medicine medicine Animals Channel blocker Pharmacology Tetraethylammonium Dose-Response Relationship Drug Long-term potentiation Population spike Endocrinology chemistry Potassium Receptors Cholecystokinin Tetanic stimulation hormones hormone substitutes and hormone antagonists |
| Zdroj: | Japanese journal of pharmacology. 68(4) |
| ISSN: | 0021-5198 |
| Popis: | Effects of cholecystokinin octapeptide (CCK-8) on long-term potentiation (LTP) of CA1 synaptic transmission induced by tetanic stimulation of the input fibers were examined in guinea pig hippocampal slices. CCK-8 and a selective agonist for the CCKB receptor, non-sulfated CCK-8, dose-dependently augmented the magnitude of LTP. Concomitant application of a selective antagonist for the CCKB receptor subtype, L-365, 260 (3R(+)-N-(2, 3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1, 4-benzodiazepine-3-yl)-N''-(3-methylphenyl)urea), completely blocked the augmentation of LTP induced by CCK-8, whereas a selective CCKA-receptor antagonist, L-364, 718 (3S(−)-N-(2, 3-dihydro-1-methyl-2-oxo-5-phenyl-IH-1, 4-benzodiazepine)), had little effect. Thus, enhancement of LTP by CCK appears to be mediated by CCKB receptors. Furthermore, CCK-8 enhanced paired-pulse facilitation at a concentration of 10-7 M without affecting the amplitude of the population spike induced by single stimulation. This effect was mimicked by a low dose of tetraethylammonium (TEA), a K+ channel blocker. Moreover, both CCK-8 and TEA reduced the late component of evoked field potentials. This late evoked potential was diminished by increasing the extracellular K+ concentration. It is suggested that CCK-8 reduces the K+ conductance in CA1 pyramidal neurons. This reduction in the K+ conductance might be related to enhancement of the LTP. |
| Databáze: | OpenAIRE |
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