Muscarinic receptor M2 in cat visual cortex: Laminar distribution, relationship to γ‐aminobutyric acidergic neurons, and effect of cingulate lesions

Acetylcholine can have diverse effects on visual cortical neurons as a result of variations in postsynaptic receptor subtypes as well as the types of neurons and subcellular sites targeted. This study examines the cellular basis for cholinergic activation in visual cortex via M2 type muscarinic receptors in γ‐aminobutyric acid (GABA)‐ergic and non‐GABAergic cells, using immunocytochemical techniques. At light microscopic resolution, M2 immunoreactivity (‐ir) was seen in all layers except area and sublayer specific bands in layer 4. Subcellularly, M2‐ir occurred in both dendrites and terminals that form symmetric and asymmetric junctions. Layers 5 and 6 were characterized by axosomatic contacts that displayed labeling in the presynaptic component, and layer 6 displayed perikaryal postsynaptic staining, suggesting that corticofugal output neurons may be modulated particularly strongly via M2. Infragranular layers differed from the supragranular layers in that more labeled profiles were axonal than dendritic, indicating a dominant presynaptic effect by acetylcholine via M2 there. Unilateral cingulate cortex cuts caused reduction of cholinergic and noradrenergic fibers in the lesioned hemisphere at light microscopic resolution; at electron microscopic resolution, the synapse density and axonal M2 labeling were reduced, suggesting that M2 was localized presynaptically on extrathalamic modulatory inputs. Dual labeling with GABA in visual cortex layer 5 showed that half of M2‐labeled dendrites originated from GABAergic neurons. Given that only one‐fifth of all cortical dendritic profiles are GABAergic, this prevalence of dual labeling indicates an enrichment of M2 within GABAergic dendrites and, thus, implicates abundant postsynaptic action on GABAergic neurons via M2. In contrast, only one‐tenth of M2‐labeled terminals originated from GABAergic neurons, suggesting that the presynaptic action of acetylcholine via M2 receptors would be more selective for non‐GABAergic terminals. J. Comp. Neurol. 441:168–185, 2001. © 2001 Wiley‐Liss, Inc.

[1]  J. DeFelipe,et al.  Synaptic relationships of serotonin-immunoreactive terminal baskets on GABA neurons in the cat auditory cortex. , 1991, Cerebral cortex.

[2]  M. Raiteri,et al.  Interaction acetylcholine-glutamate in rat hippocampus: involvement of two subtypes of M-2 muscarinic receptors. , 1989, The Journal of pharmacology and experimental therapeutics.

[3]  H. Markram,et al.  Long‐lasting facilitation of excitatory postsynaptic potentials in the rat hippocampus by acetylcholine. , 1990, The Journal of physiology.

[4]  C. Gilbert,et al.  Laminar patterns of geniculocortical projection in the cat , 1976, Brain Research.

[5]  C. Aoki,et al.  Cellular and subcellular sites for noradrenergic action in the monkey dorsolateral prefrontal cortex as revealed by the immunocytochemical localization of noradrenergic receptors and axons. , 1998, Cerebral cortex.

[6]  A. Levey,et al.  Muscarinic acetylcholine receptor subtype, m2: diverse functional implications of differential synaptic localization. , 1997, Life sciences.

[7]  W. Singer,et al.  Cholinergic innervation of the cat striate cortex: A choline acetyltransferase immunocytochemical analysis , 1986, The Journal of comparative neurology.

[8]  R. Weinberg,et al.  Techniques to optimize post-embedding single and double staining for amino acid neurotransmitters. , 1992, Journal of Histochemistry and Cytochemistry.

[9]  D. Price,et al.  Identification and localization of muscarinic acetylcholine receptor proteins in brain with subtype-specific antibodies , 1991, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[10]  J. Morrison,et al.  Noradrenergic innervation of cerebral cortex: widespread effects of local cortical lesions. , 1979, Science.

[11]  A. Levey,et al.  Immunological localization of m1-m5 muscarinic acetylcholine receptors in peripheral tissues and brain. , 1993, Life sciences.

[12]  D. Ferster,et al.  The axonal arborizations of lateral geniculate neurons in the striate cortex of the cat , 1978, The Journal of comparative neurology.

[13]  T. Tsumoto,et al.  Effects of cholinergic depletion on neuron activities in the cat visual cortex. , 1987, Journal of neurophysiology.

[14]  D. McCormick,et al.  Two types of muscarinic response to acetylcholine in mammalian cortical neurons. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[15]  A. L. Humphrey,et al.  Termination patterns of individual X‐ and Y‐cell axons in the visual cortex of the cat: Projections to area 18, to the 17/18 border region, and to both areas 17 and 18 , 1985, The Journal of comparative neurology.

[16]  C. Aoki,et al.  Optimization of differential immunogold-silver and peroxidase labeling with maintenance of ultrastructure in brain sections before plastic embedding , 1990, Journal of Neuroscience Methods.

[17]  S. Hersch,et al.  Light and electron microscopic study of m2 muscarinic acetylcholine receptor in the basal forebrain of the rat , 1995, The Journal of comparative neurology.

[18]  S. Sherman,et al.  Immunocytochemistry and distribution of parabrachial terminals in the lateral geniculate nucleus of the cat: A comparison with corticogeniculate terminals , 1997, The Journal of comparative neurology.

[19]  M. Colonnier,et al.  An empirical assessment of stereological formulae applied to the counting of synaptic disks in the cerebral cortex , 1985, The Journal of comparative neurology.

[20]  T. Tsumoto,et al.  A functional role of cholinergic innervation to neurons in the cat visual cortex. , 1987, Journal of neurophysiology.

[21]  M. Raiteri,et al.  Endogenous aspartate release in the rat hippocampus is inhibited by M2 'cardiac' muscarinic receptors. , 1990, European journal of pharmacology.

[22]  L. Raymond,et al.  Regulation of ligand-gated ion channels by protein phosphorylation. , 1999, Advances in second messenger and phosphoprotein research.

[23]  L. Descarries,et al.  Noradrenaline axon terminals in adult rat neocortex: An immunocytochemical analysis in serial thin sections , 1990, Neuroscience.

[24]  A. Ashkenazi,et al.  Structural basis of muscarinic acetylcholine receptor subtype diversity. , 1988, Trends in pharmacological sciences.

[25]  D. Prince,et al.  Cholinergic switching within neocortical inhibitory networks. , 1998, Science.

[26]  B. Gordon,et al.  Lesions of nonvisual inputs affect plasticity, norepinephrine content, and acetylcholine content of visual cortex. , 1990, Journal of neurophysiology.

[27]  M. Locke.  Preservation and contrast without osmication or section staining , 1994, Microscopy research and technique.

[28]  R. Buijs,et al.  Monoaminergic fibers form conventional synapses in the cerebral cortex , 1987, Neuroscience Letters.

[29]  M. Colonnier.  Synaptic patterns on different cell types in the different laminae of the cat visual cortex. An electron microscope study. , 1968, Brain research.

[30]  J. O'leary,et al.  Structure of the area striata of the cat , 1941 .

[31]  M. Chesselet,et al.  Presynaptic regulation of neurotransmitter release in the brain: Facts and hypothesis , 1984, Neuroscience.

[32]  C. Aoki.  Postnatal changes in the laminar and subcellular distribution of NMDA-R1 subunits in the cat visual cortex as revealed by immuno-electron microscopy. , 1997, Brain research. Developmental brain research.

[33]  J. Palacios,et al.  Muscarinic M2‐selective ligands also recognize M4 receptors in the rat brain: Evidence from combined in situ hybridization and receptor autoradiography , 1992, Synapse.

[34]  A. Sillito,et al.  Cholinergic modulation of the functional organization of the cat visual cortex , 1983, Brain Research.

[35]  J DeFelipe,et al.  Estimation of the number of synapses in the cerebral cortex: methodological considerations. , 1999, Cerebral cortex.

[36]  J. Boyd,et al.  Laminar and columnar patterns of geniculocortical projections in the cat: Relationship to cytochrome oxidase , 1996, The Journal of comparative neurology.

[37]  P. Somogyi,et al.  Enrichment of cholinergic synaptic terminals on GABAergic neurons and coexistence of immunoreactive GABA and choline acetyltransferase in the same synaptic terminals in the striate cortex of the cat , 1991, The Journal of comparative neurology.

[38]  J. DeFelipe,et al.  The pyramidal neuron of the cerebral cortex: Morphological and chemical characteristics of the synaptic inputs , 1992, Progress in Neurobiology.

[39]  A I Levey,et al.  Distribution of muscarinic cholinergic receptor proteins m1 to m4 in area 17 of normal and monocularly deprived rhesus monkeys , 1997, The Journal of comparative neurology.

[40]  P. Somogyi,et al.  Synaptic connections of morphologically identified and physiologically characterized large basket cells in the striate cortex of cat , 1983, Neuroscience.

[41]  P Rakic,et al.  Selective expression of m2 muscarinic receptor in the parvocellular channel of the primate visual cortex. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[42]  B. K. Hartman,et al.  Ultrastructural and morphometric features of the acetylcholine innervation in adult rat parietal cortex: An electron microscopic study in serial sections , 1994, The Journal of comparative neurology.

[43]  A. L. Humphrey,et al.  Projection patterns of individual X‐ and Y‐cell axons from the lateral geniculate nucleus to cortical area 17 in the cat , 1985, The Journal of comparative neurology.

[44]  E. Veznedaroglu,et al.  Elimination of artifactual labeling of hippocampal mossy fibers seen follong pre‐embedding immunogold‐silver technique by pretreatment with zinc chelator , 1992, Microscopy research and technique.

[45]  R. North,et al.  Acetylcholine hyperpolarizes central neurones by acting on an M2 muscarinic receptor , 1986, Nature.

[46]  G. Prusky,et al.  The distribution of M1 and M2 muscarinic acetylcholine receptor subtypes in the developing cat visual cortex. , 1990, Brain research. Developmental brain research.

[47]  D. McCormick.  Cholinergic and noradrenergic modulation of thalamocortical processing , 1989, Trends in Neurosciences.

[48]  C. Gilbert.  Microcircuitry of the visual cortex. , 1983, Annual review of neuroscience.

[49]  Anita E. Bandrowski,et al.  Activation of muscarinic receptors modulates NMDA receptor-mediated responses in auditory cortex , 1997, Experimental Brain Research.

[50]  P S Goldman-Rakic,et al.  Association of m1 and m2 muscarinic receptor proteins with asymmetric synapses in the primate cerebral cortex: morphological evidence for cholinergic modulation of excitatory neurotransmission. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[51]  G. Henry,et al.  Anatomical organization of the primary visual cortex (area 17) of the cat. A comparison with area 17 of the macaque monkey , 1979, The Journal of comparative neurology.

[52]  J. Wess,et al.  Antagonist binding profiles of five cloned human muscarinic receptor subtypes. , 1991, The Journal of pharmacology and experimental therapeutics.

[53]  P. Somogyi,et al.  Evidence for interlaminar inhibitory circuits in the striate cortex of the cat , 1987, The Journal of comparative neurology.

[54]  P. Goldman-Rakic,et al.  Localization of the m2 muscarinic acetylcholine receptor protein and mRNA in cortical neurons of the normal and cholinergically deafferented rhesus monkey , 1998, The Journal of comparative neurology.

[55]  H. Kennedy.  Types of synapses contacting the soma of corticotectal cells in the visual cortex of the cat , 1982, Neuroscience.

[56]  C. Aoki,et al.  Cholinergic terminals in the cat visual cortex: Ultrastructural basis for interaction with glutamate-immunoreactive neurons and other cells , 1992, Visual Neuroscience.