Cholinergic neurons of the nucleus basalis of Meynert receive cholinergic, catecholaminergic and GABAergic synapses: an electron microscopic investigation in the monkey

• Published in: Neuroscience Vol. 88; no. 1; pp. 241 - 255
• Main Authors: Smiley, J.F, Mesulam, M.-M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1999; Elsevier
• Subjects: acetylcholine; Animals; Axons - enzymology; Axons - ultrastructure; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Choline O-Acetyltransferase - analysis; Dendrites - enzymology; Dendrites - ultrastructure; dopamine; Female; Fundamental and applied biological sciences. Psychology; GABA; Glutamate Decarboxylase - analysis; Macaca nemestrina; Microscopy, Immunoelectron; Nerve Fibers, Myelinated - enzymology; Nerve Fibers, Myelinated - ultrastructure; Neurons - enzymology; Neurons - physiology; Neurons - ultrastructure; norepinephrine; primate; Substantia Innominata - physiology; Substantia Innominata - ultrastructure; Synapses - enzymology; Synapses - physiology; Synapses - ultrastructure; Tyrosine 3-Monooxygenase - analysis; Vertebrates: nervous system and sense organs; norepinephrine; ABC, avidin–biotin–peroxidase complex; NADPH, reduced nicotinamide adenine dinucleotide phosphate; primate; Ch4, cholinergic neurons of the nucleus basalis of Meynert; nbM, nucleus basalis of Meynert; TH, tyrosine hydroxylase; GAD, glutamate decarboxylase; GABA; ChAT, choline acetyltransferase; acetylcholine; dopamine; Cholinergic neuron; Dopamine; Central nervous system; Monkey; Catecholamine; Vertebrata; Nucleus basalis; Synapse; Mammalia; Ultrastructure; Neurotransmitter; Primates; Acetylcholine; Norepinephrine; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(98)00202-4

An electron microscopic analysis of the nucleus basalis in the macaque monkey was carried out following the immunohistochemical labeling of choline acetyltransferase, either by itself or in conjunction with glutamate decarboxylase or tyrosine hydroxylase. Cholinergic axon varicosities were frequently encountered, and formed large, usually asymmetric, synapses on both choline acetyltransferase-immunopositive and -immunonegative dendrites of nucleus basalis neurons. Catecholaminergic (tyrosine hydroxylase-immunoreactive) axon varicosities formed synapses which in most cases were classified as asymmetric, and glutamate decarboxylase-immunoreactive (GABAergic) axons formed clearly symmetric synapses, each on to choline acetyltransferase-immunopositive or -immunonegative dendrites. These findings indicate that cholinergic cells in the nucleus basalis of the monkey, also known as Ch4 neurons, receive numerous synaptic inputs from cholinergic, catecholaminergic and GABAergic axons.