Ciliary neurotrophic factor-immunoreactivity in olfactory sensory neurons

• Published in: Neuroscience Vol. 134; no. 4; pp. 1179 - 1194
• Main Authors: Langenhan, T., Sendtner, M., Holtmann, B., Carroll, P., Asan, E.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2005; Elsevier
• Subjects: Animals; Apoptosis - physiology; Biological and medical sciences; Ciliary Neurotrophic Factor - metabolism; electron microscopy; Female; Fundamental and applied biological sciences. Psychology; Imaging, Three-Dimensional; Immunohistochemistry; In Situ Nick-End Labeling; Male; Mice; Mice, Knockout; Microscopy, Electron, Transmission; neuronal cell death; Olfactory Bulb - cytology; Olfactory Bulb - pathology; olfactory epithelium; olfactory information processing; Olfactory Pathways - cytology; Olfactory Pathways - metabolism; Olfactory Pathways - pathology; Olfactory Receptor Neurons - cytology; Olfactory Receptor Neurons - metabolism; Olfactory Receptor Neurons - ultrastructure; Olfactory system and olfaction. Gustatory system and gustation; Rats; Rats, Wistar; Vertebrates: nervous system and sense organs; CNTF; RT; BL; PFA; olfactory information processing; cha-CNTFp; NiDAB; OB; OE; olfactory epithelium; electron microscopy; GA; NDS; GOD; OL; a-CNTFm; ON; PBS; OR; CASP; DAB; DAPI; ir; neuronal cell death; GAP43; OMP; ga-CNTFp; ra-CNTFp; NGS; Cell death; Information processing; Sensory neuron; Olfactory epithelium; Ciliary neurotrophic factor; Electron microscopy; Olfactory system
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2005.05.017

Ciliary neurotrophic factor (CNTF) has been implicated in processes of neuroprotection, axonal regeneration and synaptogenesis in the lesioned CNS. In the olfactory system, which is characterized by particularly robust neuroplasticity throughout life, the concentration of CNTF is high even under physiological conditions. In the present study, the cellular localization of CNTF-immunoreactivity was studied in the rat and mouse olfactory epithelium. In both species, individual olfactory sensory neurons (ONs) displayed intense CNTF-immunoreactivity. The number of CNTF-ir ONs varied interindividually in rats and was lower in mice than in rats. In olfactory epithelia of mice expressing β-galactosidase under control of the CNTF promoter, cells of the ON layer were immunoreactive for the reporter protein. CNTF-ir ONs were olfactory marker protein-positive and growth associated protein 43-negative. CNTF-ir ONs lacked apoptotic markers, and the number of specifically labeled ONs was apparently unchanged after light chemical lesioning of the epithelium, indicating that CNTF-immunoreactivity was not associated with ON death. Electron microscopy of CNTF-ir ON axons in innervated olfactory bulb glomeruli documented that they formed typical ON axonal synapses with target neurons. Three dimensional reconstructions of bulb pairs showed a striking similarity of the positions of glomeruli innervated by CNTF-ir ON axons in left and right bulbs of individual animals and interindividually. The number of innervated glomeruli differed interindividually in rats and was lower in mice than in rats. The results show that in rodents CNTF-immunoreactivity occurs in a subset of mature, functionally competent ONs. The localization of target glomeruli suggests that CNTF-immunoreactivity may be associated with the expression and/or activation of specific olfactory receptor proteins.