Cholinoceptive neurons without acetylcholinesterase activity and enzyme- positive neurons without cholinergic synaptic innervation are present in the main olfactory bulb of adult rat

P. Kasa, S. Karcsu, I. Kovacs, J. R. Wolff

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Light and electron microscopic histochemistry revealed acetylcholinesterase-positive and acetylcholinesterase-negative neurons in the main olfactory bulb of adult rat. Their distribution patterns on various neuron types have been analysed in detail. (1) No acetylcholinesterase staining could be demonstrated in the granule cells which receive a large number of the cholinergic synapses. (2) In contrast, enzyme activity was present in the soma and dendrites in most of the non-cholinergic and non- cholinoceptive relay cells (mitral cells and tufted cells) and in a subset of short-axon interneurons, where cholinergic synapses could not be detected. (3) Within the neuropil of glomeruli, two compartments were present, one of which was free of acetylcholinesterase-positive structures, while many enzyme-positive neuronal elements were seen in the other. (4) Characteristically, cholinergic and non-cholinergic neuronal structures showed triadic arrangements. (5) The axonal release of acetylcholinesterase from cholinergic axons is probable. It is suggested that, in the olfactory bulb, acetylcholinesterase is released by cholinergic afferent axons, and it is the cholinergic synapses that determine which postsynaptic neurons are cholinoceptive rather than the intraneuronal presence of acetylcholinesterase. In the main olfactory bulb, the acetylcholinesterase present in the relay cells therefore appears to have functions other than the hydrolysis of acetylcholine.

Original languageEnglish
Pages (from-to)831-844
Number of pages14
JournalNeuroscience
Volume73
Issue number3
DOIs
Publication statusPublished - Aug 1996

Keywords

  • acetylcholinesterase
  • histochemistry
  • olfactory bulb
  • rat
  • release
  • triad

ASJC Scopus subject areas

  • Neuroscience(all)

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