Ciliary neurotrophic factor in the olfactory bulb of rats and mice

• Published in: Neuroscience Vol. 120; no. 1; pp. 99 - 112
• Main Authors: Asan, E., Langenhan, T., Holtmann, B., Bock, H., Sendtner, M., Carroll, P.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2003; Elsevier
• Subjects: Animals; Biological and medical sciences; Ciliary Neurotrophic Factor - analysis; Ciliary Neurotrophic Factor - deficiency; Ciliary Neurotrophic Factor - genetics; ensheathing cells; Female; Fundamental and applied biological sciences. Psychology; glial fibrillary acidic protein; immunocytochemistry; Male; Mice; Mice, Knockout; neural cell adhesion molecule; neurogenesis; Olfactory Bulb - chemistry; Olfactory Bulb - ultrastructure; olfactory neurons; Olfactory system and olfaction. Gustatory system and gustation; Rats; Rats, Wistar; Vertebrates: nervous system and sense organs; ensheathing cells; CNTF; NCAM; neural cell adhesion molecule; PFA; FGF2; NiDAB; NLS; olfactory neurons; neurogenesis; GA; NDS; GOD; a-CNTFm; ON; PSA; PBS; DAB; BDNF; immunocytochemistry; ir; GFAP; OMP; ga-CNTFp; ra-CNTFp; CNTFRα; NGS; glial fibrillary acidic protein; Rat; Rodentia; Central nervous system; Ciliary neurotrophic factor; Neurotrophic factor; Vertebrata; Mammalia; Olfactory pathway; Mouse; Olfactory bulb; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(03)00211-2

Ciliary neurotrophic factor (CNTF) is primarily regarded as an astrocytic lesion factor, promoting neuronal survival and influencing plasticity processes in deafferented areas of the CNS. Postnatal loss of neurons in CNTF-deficient mice indicates a function of the factor also under physiological conditions. In the olfactory bulb, where neurogenesis, axo- and synaptogenesis continue throughout life, CNTF content is constitutively high. The cellular localization of CNTF in the rat olfactory bulb is not fully resolved, and species differences between mouse and rat are not yet characterized. In the present study, four different CNTF antibodies and double immunolabeling with specific markers for glial and neuronal cells were used to study the cellular localization of CNTF in rat and mouse olfactory bulb. Specificity of the detection was checked with tissue from CNTF-deficient mice, and investigations were complemented by immunolocalization of reporter protein in mice synthesizing β-galactosidase under control of the CNTF promoter (CNTF lacZ-knock-in mice). In both species, CNTF localized to ensheathing cell nuclei, cell bodies and axon-enveloping processes. Additionally, individual axons of olfactory neurons were CNTF immunoreactive. Both CNTF protein content and immunoreaction intensity were lower in mice than in rats. Scattered lightly CNTF-reactive cells were found in the granular and external plexiform layers in rats. Some CNTF-positive cells were associated with immunoreactivity for the polysialylated form of the neural cell adhesion molecule, which is expressed by maturing interneurons derived from the rostral migratory stream. In CNTF lacZ-knock-in mice, β-galactosidase reactivity was found in ensheathing cells of the olfactory nerve layer, and in cells of the glomerular, external plexiform and granular layers. The study proves that CNTF is localized in glial and neuronal structures in the rodent olfactory bulb. Results in mice provide a basis for investigations concerning the effects of a lack of the factor in CNTF-deficient mice.