Limits...
Olfactory epithelium changes in germfree mice.

François A, Grebert D, Rhimi M, Mariadassou M, Naudon L, Rabot S, Meunier N - Sci Rep (2016)

Bottom Line: These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes.Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium.As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

View Article: PubMed Central - PubMed

Affiliation: NBO, UVSQ, INRA, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.

ABSTRACT
Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other epithelia. In the present study, we present the first description of the bacterial communities associated with the olfactory epithelium and explored differences in olfactory epithelium characteristics between germfree and conventional, specific pathogen-free, mice. While the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. Using electro-olfactogram, we recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice as well as altered responses kinetics. These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium. As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

No MeSH data available.


Related in: MedlinePlus

Modulation of the expression of genes related to odorant detection in germfree animals.Quantitative PCR (qPCR) analysis of cDNAs from olfactory mucosa. Genes are grouped by functions; (A) olfactory receptors sensitive to odorants tested in the EOG experiment; (B) main olfactory transduction pathway components; (C) olfactory binding proteins; (D) detoxifying enzymes. Their expression levels were normalized to that of β-tubIII (A,B) or β-actin (C,D) and are given as mean ± SEM (n = 7). (*) P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835764&req=5

f4: Modulation of the expression of genes related to odorant detection in germfree animals.Quantitative PCR (qPCR) analysis of cDNAs from olfactory mucosa. Genes are grouped by functions; (A) olfactory receptors sensitive to odorants tested in the EOG experiment; (B) main olfactory transduction pathway components; (C) olfactory binding proteins; (D) detoxifying enzymes. Their expression levels were normalized to that of β-tubIII (A,B) or β-actin (C,D) and are given as mean ± SEM (n = 7). (*) P < 0.05.

Mentions: The EOG recordings showed that the presence of microbiota influences odorant detection, we therefore analysed the expression level of various genes related to odorant detection and metabolism, and to olfactory signal transduction. We first examined the level of expression of OR related to the odorants used in the EOG experiments18. While the heptanal sensitive Olfr2 expression was significantly decreased, the expression of the heptanoic acid sensitive Olfr937 and of the acetophenone sensitive Olfr151 were not statistically different in the absence of microbiota (Fig. 4A). Most volatile odorants are transduced through the activation of a G protein Golf, which in turns activates the adenylate cyclase III (ACIII). The rise in cAMP level in turn activates a CNG channel (Cnga2) and this rise is counterbalanced by the cAMP degrading phosphodiesterase PDE1C2. While we observed a global increase in the EOG signal in response to various odorants in germfree animals, all components of the olfactory transduction cascade were significantly more expressed in conventional animals (Fig. 4B). Odorants are hydrophobic and olfactory binding proteins, among others, are thought to improve the solubilisation of odorants in the nasal mucus, allowing them to reach the olfactory receptors9. Because the OE-associated microbiota could interfere with this step, we also examined the level of expression of the two olfactory binding proteins which have been characterised in mice, OBP1a and OBP1b. Both were largely overexpressed in germfree animals, although significance was not reached for OBP1a (p = 0.055), due to an important individual heterogeneity (Fig. 4C). Finally, odorants are rapidly detoxified in the OE through various pathways, involving mainly cytochrome P450 enzymes, gluthathione-S-transferase (GST) and UDP-glucuronosyl transferase (UGT). We examined the expression of the genes encoding the main CYP450, GST and UGT isozymes in the OE9. While we observed a global decrease of their expression level in the germfree animals, it reached significance only for CYP2A5 and UGT2A1 (Fig. 4D).


Olfactory epithelium changes in germfree mice.

François A, Grebert D, Rhimi M, Mariadassou M, Naudon L, Rabot S, Meunier N - Sci Rep (2016)

Modulation of the expression of genes related to odorant detection in germfree animals.Quantitative PCR (qPCR) analysis of cDNAs from olfactory mucosa. Genes are grouped by functions; (A) olfactory receptors sensitive to odorants tested in the EOG experiment; (B) main olfactory transduction pathway components; (C) olfactory binding proteins; (D) detoxifying enzymes. Their expression levels were normalized to that of β-tubIII (A,B) or β-actin (C,D) and are given as mean ± SEM (n = 7). (*) P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835764&req=5

f4: Modulation of the expression of genes related to odorant detection in germfree animals.Quantitative PCR (qPCR) analysis of cDNAs from olfactory mucosa. Genes are grouped by functions; (A) olfactory receptors sensitive to odorants tested in the EOG experiment; (B) main olfactory transduction pathway components; (C) olfactory binding proteins; (D) detoxifying enzymes. Their expression levels were normalized to that of β-tubIII (A,B) or β-actin (C,D) and are given as mean ± SEM (n = 7). (*) P < 0.05.
Mentions: The EOG recordings showed that the presence of microbiota influences odorant detection, we therefore analysed the expression level of various genes related to odorant detection and metabolism, and to olfactory signal transduction. We first examined the level of expression of OR related to the odorants used in the EOG experiments18. While the heptanal sensitive Olfr2 expression was significantly decreased, the expression of the heptanoic acid sensitive Olfr937 and of the acetophenone sensitive Olfr151 were not statistically different in the absence of microbiota (Fig. 4A). Most volatile odorants are transduced through the activation of a G protein Golf, which in turns activates the adenylate cyclase III (ACIII). The rise in cAMP level in turn activates a CNG channel (Cnga2) and this rise is counterbalanced by the cAMP degrading phosphodiesterase PDE1C2. While we observed a global increase in the EOG signal in response to various odorants in germfree animals, all components of the olfactory transduction cascade were significantly more expressed in conventional animals (Fig. 4B). Odorants are hydrophobic and olfactory binding proteins, among others, are thought to improve the solubilisation of odorants in the nasal mucus, allowing them to reach the olfactory receptors9. Because the OE-associated microbiota could interfere with this step, we also examined the level of expression of the two olfactory binding proteins which have been characterised in mice, OBP1a and OBP1b. Both were largely overexpressed in germfree animals, although significance was not reached for OBP1a (p = 0.055), due to an important individual heterogeneity (Fig. 4C). Finally, odorants are rapidly detoxified in the OE through various pathways, involving mainly cytochrome P450 enzymes, gluthathione-S-transferase (GST) and UDP-glucuronosyl transferase (UGT). We examined the expression of the genes encoding the main CYP450, GST and UGT isozymes in the OE9. While we observed a global decrease of their expression level in the germfree animals, it reached significance only for CYP2A5 and UGT2A1 (Fig. 4D).

Bottom Line: These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes.Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium.As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

View Article: PubMed Central - PubMed

Affiliation: NBO, UVSQ, INRA, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.

ABSTRACT
Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other epithelia. In the present study, we present the first description of the bacterial communities associated with the olfactory epithelium and explored differences in olfactory epithelium characteristics between germfree and conventional, specific pathogen-free, mice. While the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. Using electro-olfactogram, we recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice as well as altered responses kinetics. These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium. As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

No MeSH data available.


Related in: MedlinePlus