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Adiponectin enhances the responsiveness of the olfactory system.

Loch D, Heidel C, Breer H, Strotmann J - PLoS ONE (2013)

Bottom Line: In fact, electroolfactogram recordings from olfactory epithelium incubated with exogenous adiponectin resulted in large amplitudes upon odor stimulation.It was found that in an olfactory epithelium incubated with nasally applied adiponectin the number of Egr1 positive cells was significantly higher compared to controls, suggesting that adiponectin rendered the olfactory neurons more responsive to an odorant stimulus.The results of this study indicate that adiponectin increases the responsiveness of the olfactory system, probably due to a higher responsiveness of olfactory sensory neurons.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiology, University of Hohenheim, Stuttgart, Germany.

ABSTRACT
The peptide hormone adiponectin is secreted by adipose tissue and the circulating concentration is reversely correlated with body fat mass; it is considered as starvation signal. The observation that mature sensory neurons of the main olfactory epithelium express the adiponectin receptor 1 has led to the concept that adiponectin may affect the responsiveness of the olfactory system. In fact, electroolfactogram recordings from olfactory epithelium incubated with exogenous adiponectin resulted in large amplitudes upon odor stimulation. To determine whether the responsiveness of the olfactory sensory neurons was enhanced, we have monitored the odorant-induced expression of the immediate early gene Egr1. It was found that in an olfactory epithelium incubated with nasally applied adiponectin the number of Egr1 positive cells was significantly higher compared to controls, suggesting that adiponectin rendered the olfactory neurons more responsive to an odorant stimulus. To analyze whether the augmented responsiveness of sensory neurons was strong enough to elicit a higher neuronal activity in the olfactory bulb, the number of activated periglomerular cells of a distinct glomerulus was determined by monitoring the stimulus-induced expression of c-fos. The studies were performed using the transgenic mOR256-17-IRES-tauGFP mice which allowed to visualize the corresponding glomerulus and to stimulate with a known ligand. The data indicate that upon exposure to 2,3-hexanedione in adiponectin-treated mice the number of activated periglomerular neurons was significantly increased compared to controls. The results of this study indicate that adiponectin increases the responsiveness of the olfactory system, probably due to a higher responsiveness of olfactory sensory neurons.

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Adiponectin leads to an increased responsiveness of OSNs in different regions of the olfactory epithelium.(A) Coronal section through the nasal cavity of a mouse exposed to benzaldehyde after in situ-hybridisation with an Egr1-specific antisense riboprobe. Numerals designate endoturbinates II, III, IV and ectoturbinates 2, 3; s  =  nasal septum. (B) Number [n] of Egr-1 positive cells on 50 consecutive sections through endoturbinate III of control animals (white bar) and adiponectin-treated animals (black bar) after exposure to benzaldehyde. The number of Egr-1 positive cells is significantly higher when animals are pretreated with adiponectin. (control: 187.1±47.5; adipo+: 310±96.4: P = 0.0020). All numbers in this figure are given as means ± SD. **, statistically very significant. Scale bar: 0,5 mm in A.
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pone-0075716-g004: Adiponectin leads to an increased responsiveness of OSNs in different regions of the olfactory epithelium.(A) Coronal section through the nasal cavity of a mouse exposed to benzaldehyde after in situ-hybridisation with an Egr1-specific antisense riboprobe. Numerals designate endoturbinates II, III, IV and ectoturbinates 2, 3; s  =  nasal septum. (B) Number [n] of Egr-1 positive cells on 50 consecutive sections through endoturbinate III of control animals (white bar) and adiponectin-treated animals (black bar) after exposure to benzaldehyde. The number of Egr-1 positive cells is significantly higher when animals are pretreated with adiponectin. (control: 187.1±47.5; adipo+: 310±96.4: P = 0.0020). All numbers in this figure are given as means ± SD. **, statistically very significant. Scale bar: 0,5 mm in A.

Mentions: Since it was previously shown that all mature olfactory sensory neurons appear to express the adipoR1 receptor [9], we next examined whether adiponectin leads to an increased sensitivity of OSNs also in other regions of the epithelium. Analyses of endoturbinate III (figure 4A) revealed that also in this region the number of activated OSNs was significantly higher in adiponectin treated mice (n = 10) as compared to buffer treated animals (n = 10) (figure 4B). To exclude the possibility that the increased responsiveness may be uniquely for benzaldehyde but rather than that the responsiveness of the olfactory epithelium was generally increased, a series of experiments was performed using the structurally quite different odorous compounds 1-heptanal and 2,3-hexanedione which most likely activate distinct OSN populations. It was found that upon exposure to 1-heptanal a variety of Egr1 expressing cells was visible in both buffer treated and adiponectin treated mice (figure 5A-C). Interestingly, the activated cells were located in a different region of the ectoturbinate 2 than the benzaldehyde responsive cells (figure 5A). Counting the number of Egr1 expressing OSNs revealed that after adiponectin treatment the number of 1-heptanal reactive cells was about 1.5-fold higher than control (figure 5F). A similar result was also obtained for 2,3-hexanedione (figure 5D/5E); in adiponectin treated animals the number of Egr1 expressing cells was 1.6-fold higher (figure 5F). Together, these results indicate that adiponectin induces an increased sensitivity of olfactory sensory neurons responding to very different odorous compounds.


Adiponectin enhances the responsiveness of the olfactory system.

Loch D, Heidel C, Breer H, Strotmann J - PLoS ONE (2013)

Adiponectin leads to an increased responsiveness of OSNs in different regions of the olfactory epithelium.(A) Coronal section through the nasal cavity of a mouse exposed to benzaldehyde after in situ-hybridisation with an Egr1-specific antisense riboprobe. Numerals designate endoturbinates II, III, IV and ectoturbinates 2, 3; s  =  nasal septum. (B) Number [n] of Egr-1 positive cells on 50 consecutive sections through endoturbinate III of control animals (white bar) and adiponectin-treated animals (black bar) after exposure to benzaldehyde. The number of Egr-1 positive cells is significantly higher when animals are pretreated with adiponectin. (control: 187.1±47.5; adipo+: 310±96.4: P = 0.0020). All numbers in this figure are given as means ± SD. **, statistically very significant. Scale bar: 0,5 mm in A.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3794965&req=5

pone-0075716-g004: Adiponectin leads to an increased responsiveness of OSNs in different regions of the olfactory epithelium.(A) Coronal section through the nasal cavity of a mouse exposed to benzaldehyde after in situ-hybridisation with an Egr1-specific antisense riboprobe. Numerals designate endoturbinates II, III, IV and ectoturbinates 2, 3; s  =  nasal septum. (B) Number [n] of Egr-1 positive cells on 50 consecutive sections through endoturbinate III of control animals (white bar) and adiponectin-treated animals (black bar) after exposure to benzaldehyde. The number of Egr-1 positive cells is significantly higher when animals are pretreated with adiponectin. (control: 187.1±47.5; adipo+: 310±96.4: P = 0.0020). All numbers in this figure are given as means ± SD. **, statistically very significant. Scale bar: 0,5 mm in A.
Mentions: Since it was previously shown that all mature olfactory sensory neurons appear to express the adipoR1 receptor [9], we next examined whether adiponectin leads to an increased sensitivity of OSNs also in other regions of the epithelium. Analyses of endoturbinate III (figure 4A) revealed that also in this region the number of activated OSNs was significantly higher in adiponectin treated mice (n = 10) as compared to buffer treated animals (n = 10) (figure 4B). To exclude the possibility that the increased responsiveness may be uniquely for benzaldehyde but rather than that the responsiveness of the olfactory epithelium was generally increased, a series of experiments was performed using the structurally quite different odorous compounds 1-heptanal and 2,3-hexanedione which most likely activate distinct OSN populations. It was found that upon exposure to 1-heptanal a variety of Egr1 expressing cells was visible in both buffer treated and adiponectin treated mice (figure 5A-C). Interestingly, the activated cells were located in a different region of the ectoturbinate 2 than the benzaldehyde responsive cells (figure 5A). Counting the number of Egr1 expressing OSNs revealed that after adiponectin treatment the number of 1-heptanal reactive cells was about 1.5-fold higher than control (figure 5F). A similar result was also obtained for 2,3-hexanedione (figure 5D/5E); in adiponectin treated animals the number of Egr1 expressing cells was 1.6-fold higher (figure 5F). Together, these results indicate that adiponectin induces an increased sensitivity of olfactory sensory neurons responding to very different odorous compounds.

Bottom Line: In fact, electroolfactogram recordings from olfactory epithelium incubated with exogenous adiponectin resulted in large amplitudes upon odor stimulation.It was found that in an olfactory epithelium incubated with nasally applied adiponectin the number of Egr1 positive cells was significantly higher compared to controls, suggesting that adiponectin rendered the olfactory neurons more responsive to an odorant stimulus.The results of this study indicate that adiponectin increases the responsiveness of the olfactory system, probably due to a higher responsiveness of olfactory sensory neurons.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiology, University of Hohenheim, Stuttgart, Germany.

ABSTRACT
The peptide hormone adiponectin is secreted by adipose tissue and the circulating concentration is reversely correlated with body fat mass; it is considered as starvation signal. The observation that mature sensory neurons of the main olfactory epithelium express the adiponectin receptor 1 has led to the concept that adiponectin may affect the responsiveness of the olfactory system. In fact, electroolfactogram recordings from olfactory epithelium incubated with exogenous adiponectin resulted in large amplitudes upon odor stimulation. To determine whether the responsiveness of the olfactory sensory neurons was enhanced, we have monitored the odorant-induced expression of the immediate early gene Egr1. It was found that in an olfactory epithelium incubated with nasally applied adiponectin the number of Egr1 positive cells was significantly higher compared to controls, suggesting that adiponectin rendered the olfactory neurons more responsive to an odorant stimulus. To analyze whether the augmented responsiveness of sensory neurons was strong enough to elicit a higher neuronal activity in the olfactory bulb, the number of activated periglomerular cells of a distinct glomerulus was determined by monitoring the stimulus-induced expression of c-fos. The studies were performed using the transgenic mOR256-17-IRES-tauGFP mice which allowed to visualize the corresponding glomerulus and to stimulate with a known ligand. The data indicate that upon exposure to 2,3-hexanedione in adiponectin-treated mice the number of activated periglomerular neurons was significantly increased compared to controls. The results of this study indicate that adiponectin increases the responsiveness of the olfactory system, probably due to a higher responsiveness of olfactory sensory neurons.

Show MeSH
Related in: MedlinePlus