Ultrastructural characterization of the acetylcholine innervation in adult rat neostriatum

Contant, Chantal; Umbriaco, Denis; Garcia, Sylvia; Watkins, Kenneth C.; Descarries, Laurent

doi:10.1016/0306-4522(95)00507-2

Cited by 157 publications

(156 citation statements)

References 41 publications

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“…The membrane potential was initially Ϫ53 mV, and the recording was made at 35 Ϯ 2°C. Taken and adapted from Bennett and Wilson, 1999. ergic varicosities also is extremely high (Bolam et al, 1984;Butcher and Woolfe, 1984;Phelps et al, 1985;Smith and Bolam, 1990;Contant et al, 1996). Quantitative electron microscopy indicates that there are about 2 ϫ 10 8 ACh varicosities/mm 3 in the striatum, and each striatal cholinergic interneuron has 500,000 axon varicosities.…”

Section: Cholinergic Interneurons In the Striatummentioning

confidence: 96%

“…Quantitative electron microscopy indicates that there are about 2 ϫ 10 8 ACh varicosities/mm 3 in the striatum, and each striatal cholinergic interneuron has 500,000 axon varicosities. A 10 m-radius sphere of striatal neuropil contains about 400 DA and 400 ACh axon terminals (Contant et al, 1996;Descarries and Mechawar, 2000). Like dopaminergic synapses, cholinergic synapses form primarily onto distal dendrites and dendritic spine necks in the striatum (Bolam et al, 1984;Phelps et al, 1985).…”

Section: Cholinergic Interneurons In the Striatummentioning

confidence: 99%

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Cholinergic interneuron characteristics and nicotinic properties in the striatum

2002

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ABSTRACT:The neostriatum (dorsal striatum) is composed of the caudate and putamen. The ventral striatum is the ventral conjunction of the caudate and putamen that merges into and includes the nucleus accumbens and striatal portions of the olfactory tubercle. About 2% of the striatal neurons are cholinergic. Most cholinergic neurons in the central nervous system make diffuse projections that sparsely innervate relatively broad areas. In the striatum, however, the cholinergic neurons are interneurons that provide very dense local innervation. The cholinergic interneurons provide an ongoing acetylcholine (ACh) signal by firing action potentials tonically at about 5 Hz. A high concentration of acetylcholinesterase in the striatum rapidly terminates the ACh signal, and thereby minimizes desensitization of nicotinic acetylcholine receptors. Among the many muscarinic and nicotinic striatal mechanisms, the ongoing nicotinic activity potently enhances dopamine release. This process is among those in the striatum that link the two extensive and dense local arbors of the cholinergic interneurons and dopaminergic afferent fibers. During a conditioned motor task, cholinergic interneurons respond with a pause in their tonic firing. It is reasonable to hypothesize that this pause in the cholinergic activity alters action potential dependent dopamine release. The correlated response of these two broad and dense neurotransmitter systems helps to coordinate the output of the striatum, and is likely to be an important process in sensorimotor planning and learning.

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Section: Cholinergic Interneurons In the Striatummentioning

confidence: 96%

Section: Cholinergic Interneurons In the Striatummentioning

confidence: 99%

Cholinergic interneuron characteristics and nicotinic properties in the striatum

2002

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“…However, DA release is governed by a basal tone of endogenous ACh acting at presynaptic nAChRs on DA axons (Rice and Cragg, 2004;Zhang and Sulzer, 2004;Zhou et al, 2001). Local cholinergic interneurons in striatal slice preparations are spontaneously active as they are in vivo (Aosaki et al, 1994;Bennett and Wilson, 1999), and provide a dense network of ACh release sites (Contant et al, 1996;Descarries and Mechawar, 2000;Zhou et al, 2003) that can provide this background of endogenous ACh (Zhou et al, 2001). ACh release evoked by the stimulus does not appear to contribute to these effects: similar results were seen in pilot studies in parasagittal slices in which DA release was elicited by remote pathway stimulation (up to 1000 mm ventrocaudal from the recording electrode) (Rice and Cragg, 2004).…”

Section: Electrical Stimulationmentioning

confidence: 99%

α6-Containing Nicotinic Acetylcholine Receptors Dominate the Nicotine Control of Dopamine Neurotransmission in Nucleus Accumbens

Exley

Clements

Hartung

et al. 2007

Neuropsychopharmacol

227

262

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Modulation of striatal dopamine (DA) neurotransmission plays a fundamental role in the reinforcing and ultimately addictive effects of nicotine. Nicotine, by desensitizing b2 subunit-containing (b2*) nicotinic acetylcholine receptors (nAChRs) on striatal DA axons, significantly enhances how DA is released by reward-related burst activity compared to nonreward-related tonic activity. This action provides a synaptic mechanism for nicotine to facilitate the DA-dependent reinforcement. The subfamily of b2*-nAChRs responsible for these potent synaptic effects could offer a molecular target for therapeutic strategies in nicotine addiction. We explored the role of a6b2*-nAChRs in the nucleus accumbens (NAc) and caudate-putamen (CPu) by observing action potential-dependent DA release from synapses in real-time using fast-scan cyclic voltammetry at carbon-fiber microelectrodes in mouse striatal slices. The a6-specific antagonist a-conotoxin-MII suppressed DA release evoked by single and low-frequency action potentials and concurrently enhanced release by high-frequency bursts in a manner similar to the b2*-selective antagonist dihydro-b-erythroidine (DHbE) in NAc, but less so in CPu. The greater role for a6*-nAChRs in NAc was not due to any confounding regional difference in ACh tone since elevated ACh levels (after the acetylcholinesterase inhibitor ambenonium) had similar outcomes in NAc and CPu. Rather, there appear to be underlying differences in nAChR subtype function in NAc and CPu. In summary, we reveal that a6b2*-nAChRs dominate the effects of nicotine on DA release in NAc, whereas in CPu their role is minor alongside other b2*-nAChRs (eg a4*), These data offer new insights to suggest striatal a6*-nAChRs as a molecular target for a therapeutic strategy for nicotine addiction.

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“…Although one could argue, based on studies at the neuromuscular junction, that such concentrations are physiologically relevant, very little is known about ACh release in the CNS. Electron microscopic studies suggest that release of ACh and subsequent signaling might be mediated by "volume" transmission, dependent on diffusion of the released ACh (Contant et al, 1996;Descarries et al, 1997;Mechawar et al, 2002). If that's the case, then the actual concentrations of the transmitter at the mossy fiber synapse remains unknown.…”

Section: Role Of Camkii In Amplitude Changes After Nachr Activationmentioning

confidence: 99%

Action Potential-Independent and Nicotinic Receptor-Mediated Concerted Release of Multiple Quanta at Hippocampal CA3–Mossy Fiber Synapses

Sharma

Grybko²,

Vijayaraghavan

2008

J. Neurosci.

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Presynaptic action potential-independent transmitter release is a potential means of information transfer across synapses. We show that in the hippocampal mossy fiber boutons, activation of the ␣7-subtype of nicotinic acetylcholine receptors (␣7-nAChRs) results in a large increase in the amplitude of spontaneous events, resulting from concerted release of multiple quanta from the mossy fiber boutons. This amplitude increase is abolished at low temperatures. Activation of ␣7-nAChRs causes a rise in intraterminal calcium at mossy fiber boutons, involving ryanodine receptors. Regulation of concerted release requires the subsequent activation of presynaptic calcium/ calmodulin-dependent protein kinase II (CaMKII). Activation of CaMKII is required to drive presynaptic action potential-independent transmission at the mossy fiber-CA3 pyramidal cell synapse. The effects of ␣7-nAChR activation are mediated by biologically relevant doses of nicotine. Our results demonstrate a novel form of synaptic plasticity mediated by presynaptic ␣7-nAChRs and store calcium that is temporally different and might respond to a different history of synaptic activity than that mediated by incoming action potentials.

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Ultrastructural characterization of the acetylcholine innervation in adult rat neostriatum

Cited by 157 publications

References 41 publications

Cholinergic interneuron characteristics and nicotinic properties in the striatum

Cholinergic interneuron characteristics and nicotinic properties in the striatum

α6-Containing Nicotinic Acetylcholine Receptors Dominate the Nicotine Control of Dopamine Neurotransmission in Nucleus Accumbens

Action Potential-Independent and Nicotinic Receptor-Mediated Concerted Release of Multiple Quanta at Hippocampal CA3–Mossy Fiber Synapses

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