Elsevier

Neuroscience

Volume 71, Issue 4, April 1996, Pages 937-947
Neuroscience

Ultrastructural characterization of the acetylcholine innervation in adult rat neostriatum

https://doi.org/10.1016/0306-4522(95)00507-2Get rights and content

Abstract

The ultrastructural features of acetylcholine axon terminals (varicosities) in adult rat neostriatum were characterized by electron microscopy after immunostaining with a sensitive monoclonal antibody against rat choline acetyltransferase. Several hundred single sections from these varicosities were analysed for shape, size and content, presence of a synaptic membrane specialization, and composition of the microenvironment. An equivalent number of unlabeled varicosities selected at random from the same micrographs were similarly examined. The immunostained varicosity profiles were relatively small and seldom showed a junctional membrane specialization. Stereological extrapolation to the whole volume of these varicosities indicated that less than 10% were synaptic. Far fewer dendritic spines were juxtaposed to these predominantly asynaptic profiles than to their unlabeled counterparts. This difference seemed imputable to the low synaptic incidence of the acetylcholine varicosities and was consistent with the view that these are randomly distributed in relation to surrounding elements.

The bulk of the data was suggestive of volume transmission. This raised the possibility that, in such a densely innervated area, a basal level of acetylcholine is permanently maintained around all cellular elements, contributing to the modulatory properties of this transmitter. This basal level of acetylcholine could also serve as a regulatory signal controlling the expression of different receptor subtypes in neurons, glia and blood vessels.

Reference (55)

  • DescarriesL. et al.

    Noradrenergic axon terminals in the cerebral cortex of rat. III. Topometric ultrastructural analysis

    Brain Res.

    (1977)
  • Di ChiaraG. et al.

    Modulatory functions of neurotransmitters in the striatum: ACh/dopamine/NMDA interactions

    Trends Neurosci.

    (1994)
  • FarberS.A. et al.

    Potentiation by choline of basal and electrically evoked acetylcholine release, as studied using a novel device which both stimulates and perfuses rat corpus striatum

    Brain Res.

    (1993)
  • FreundT.F. et al.

    Tyrosine hydroxylase-immunoreactive boutons in synaptic contact with identified striatonigral neurons, with particular reference to dendritic spines

    Neuroscience

    (1984)
  • HooverD.B. et al.

    A mapping of the distribution of acetylcholine, choline acetyltransferase and acetylcholinesterase in discrete areas of rat brain

    Brain Res.

    (1978)
  • HösliE. et al.

    Receptors for neurotransmitters on astrocytes in the mammalian central nervous system

    Prog. Neurobiol.

    (1993)
  • HouserC.R. et al.

    Organization and morphological characteristics of cholinergic neurons: an immunocytochemical study with a monoclonal antibody to choline acetyltransferase

    Brain Res.

    (1983)
  • McGeerP.L. et al.

    Neostriatal choline acetylase and cholinesterase following selective brain lesions

    Brain Res.

    (1971)
  • OleskevichS. et al.

    Ultrastructural features of the serotonin innervation in adult rat hippocampus: an immunocytochemical description in single and serial thin sections

    Neuroscience

    (1991)
  • PascualJ. et al.

    Further studies on the biochemical characterization and autoradiographic distribution of [3H]hemicholinium-3 binding sites in rat brain: a presynaptic cholinergic marker

    Pharmac. Res.

    (1991)
  • SéguélaP. et al.

    Noradrenaline axon terminals in adult rat neocortex: an immunocytochemical analysis in serial thin sections

    Neuroscience

    (1990)
  • SoghomonianJ.-J. et al.

    Serotonin innervation in adult rat neostriatum. I. Quantified regional distribution

    Brain Res.

    (1987)
  • SorimachiM. et al.

    Choline uptake by nerve terminals: a sensitive and a specific marker of cholinergic innervation

    Brain Res.

    (1974)
  • StoofJ.C. et al.

    Regulation of the activity of striatal cholinergic neurons by dopamine

    Neuroscience

    (1992)
  • WainerB.H. et al.

    Cholinergic synapses in the rat brain: a correlated light and electron microscopic immunocytochemical study employing a monoclonal antibody against choline acetyltransferase

    Brain Res.

    (1984)
  • WoolfN.J.

    Cholinergic systems in mammalian brain and spinal cord

    Prog. Neurobiol.

    (1991)
  • WoolfN.J. et al.

    Cholinergic neurons in the caudate-putamen complex proper are intrinsically organized: a combined Evans blue and acetylcholinesterase analysis

    Brain Res. Bull.

    (1981)
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