Summary
The hippocampus is among the regions in the brain richest in M1 cholinergic receptors. Topical application of acetylcholine (ACh) onto hippocampal slices produces a characteristic complex response consisting of a depolarization, an increase in input resistance especially upon depolarization and a blockade of a slow afterhyperpolarization (AHP). The first two of these responses can be recorded also in non-cholinergic septal neurons in an area which contains about 8% of the M1 muscarinic receptors found in the hippocampus. The responses of hippocampal but not septal neurons to ACh involve an increase in the spontaneous synaptic activity and a decrease in evoked responses to afferent stimulation. The dissociated hippocampal culture was used to study these presynaptic effects. The neurons in culture possess muscarinic receptors which develop gradually over a period of several weeks after plating. ACh rarely depolarizes hippocampal neurons in culture. Instead, it causes an increase in spontaneous discharge of small postsynaptic currents (PSC’s) and a marked decrease of large, evoked PSC’s. In some cultured hippocampal cells ACh reduced ICa without affecting any of several outward K currents studied. It is suggested that ACh reduces evoked activity by reducing Ca currents at presynaptic terminals.
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© 1989 Birkhäuser Verlag
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Segal, M., Greenberger, V., Markram, H. (1989). Presynaptic cholinergic action in the hippocampus. In: Frotscher, M., Misgeld, U. (eds) Central Cholinergic Synaptic Transmission. Experientia Supplementum, vol 57. Birkhäuser Basel. https://doi.org/10.1007/978-3-0348-9138-7_9
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DOI: https://doi.org/10.1007/978-3-0348-9138-7_9
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