Abstract
Mammalian retinas are innervated by histaminergic axons that originate from perikarya in the posterior hypothalamus. To identify the targets of these retinopetal axons, we localized histamine receptors (HR) in monkey and rat retinas by light and electron microscopy. In monkeys, puncta containing HR3 were found at the tips of ON-bipolar cell dendrites in cone pedicles and rod spherules, closer to the photoreceptors than the other neurotransmitter receptors. This is the first ultrastructural localization of any histamine receptor and the first direct evidence that HR3 is present on postsynaptic membranes in the central nervous system. In rat retinas, most HR1 were localized to dopaminergic amacrine cells. The differences in histamine receptor localization may reflect the differences in the activity patterns of the two species.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amacrine Cells / metabolism
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Amacrine Cells / ultrastructure
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Animals
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Dopamine / metabolism
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Efferent Pathways / metabolism
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Efferent Pathways / ultrastructure
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Histamine / metabolism*
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Immunohistochemistry
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Microscopy, Confocal
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Microscopy, Electron, Transmission
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Neurons / metabolism*
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Neurons / ultrastructure
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Papio anubis
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Photoreceptor Cells, Vertebrate / metabolism
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Photoreceptor Cells, Vertebrate / ultrastructure
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Rats
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Rats, Sprague-Dawley
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Receptors, Histamine / metabolism*
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Receptors, Histamine H1 / metabolism
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Receptors, Histamine H3 / metabolism
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Retina / metabolism*
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Retina / ultrastructure
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Retinal Bipolar Cells / metabolism
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Retinal Bipolar Cells / ultrastructure
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Species Specificity
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Synapses / metabolism*
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Synapses / ultrastructure
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Synaptic Membranes / metabolism
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Synaptic Membranes / ultrastructure
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Synaptic Transmission / physiology
Substances
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Receptors, Histamine
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Receptors, Histamine H1
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Receptors, Histamine H3
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Histamine
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Dopamine