Limits...
Combustion smoke-induced inflammation in the olfactory bulb of adult rats.

Zou YY, Yuan Y, Kan EM, Lu J, Ling EA - J Neuroinflammation (2014)

Bottom Line: The results showed a significant increase in VEGF, iNOS, eNOS, nNOS, NKCC1, and GFAP expression in the bulb tissues, with corresponding increases in inflammatory cytokines and chemokines after smoke inhalation.Concurrent to this was a drastic increase in AQP4 expression and RITC permeability.This was coupled with a significant reduction in incidence of TUNEL + cells that was not altered with administration of L-NG-nitroarginine methyl ester (L-NAME).

View Article: PubMed Central - PubMed

ABSTRACT

Background: The damaging effect of combustion smoke inhalation on the lung is widely reported but information on its effects on the olfactory bulb is lacking. This study sought to determine the effects of smoke inhalation on the olfactory bulb, whose afferent input neurons in the nasal mucosa are directly exposed to external stimuli, such as smoke.

Methods: Adult male Sprague-Dawley rats were subjected to combustion smoke inhalation and sacrificed at different time points. Changes in olfactory bulb proteins including vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), Na+-K+-Cl- cotransporter 1 (NKCC1), glial fibrillary acidic protein (GFAP), and aquaporin-4 (AQP4) were evaluated by Western blot analysis. In addition, ELISA was conducted for cytokine and chemokine levels, and double immunofluorescence labeling was carried out for GFAP/VEGF, GFAP/AQP4, NeuN/nNOS, GFAP/NKCC1, NeuN/NKCC1, GFAP/Rhodamine isothiocyanate (RITC), and transferase dUTP nick end labeling (TUNEL). Aminoguanidine was administered to determine the effects of iNOS inhibition on the targets probed after smoke inhalation.

Results: The results showed a significant increase in VEGF, iNOS, eNOS, nNOS, NKCC1, and GFAP expression in the bulb tissues, with corresponding increases in inflammatory cytokines and chemokines after smoke inhalation. Concurrent to this was a drastic increase in AQP4 expression and RITC permeability. Aminoguanidine administration decreased the expression of iNOS and RITC extravasation after smoke inhalation. This was coupled with a significant reduction in incidence of TUNEL + cells that was not altered with administration of L-NG-nitroarginine methyl ester (L-NAME).

Conclusions: These findings suggest that the upregulation of iNOS in response to smoke inhalation plays a major role in the olfactory bulb inflammatory pathophysiology, along with a concomitant increase in pro-inflammatory molecules, vascular permeability, and edema. Overall, these findings indicate that the olfactory bulb is vulnerable to smoke inhalation.

Show MeSH

Related in: MedlinePlus

NKCC1 (red) and GFAP (green) immunopositive astrocytes in the bulb tissue of the control group (A-C), the SI + S group at 24 and 72 h (D-I), and the SI + AG group at 72 h (J-L). In the C group, only sporadic astrocytes exhibit moderate NKCC1 immunofluorescence. In the SI + S group, it is evidently enhanced in hypertrophic astrocytes at 24 and 72 h (D-I), being more pronounced at 24 h (E). Colocalized expression of NKCC1 with GFAP immunoreactive astrocytes (arrows) can be seen in C, F, I and L. Immunoreactivity for both NKCC1 and GFAP is attenuated at 72 h in the SI + AG group, as compared with the SI + S group at 72 h (J-L). Scale bar =20.0 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4197300&req=5

Fig8: NKCC1 (red) and GFAP (green) immunopositive astrocytes in the bulb tissue of the control group (A-C), the SI + S group at 24 and 72 h (D-I), and the SI + AG group at 72 h (J-L). In the C group, only sporadic astrocytes exhibit moderate NKCC1 immunofluorescence. In the SI + S group, it is evidently enhanced in hypertrophic astrocytes at 24 and 72 h (D-I), being more pronounced at 24 h (E). Colocalized expression of NKCC1 with GFAP immunoreactive astrocytes (arrows) can be seen in C, F, I and L. Immunoreactivity for both NKCC1 and GFAP is attenuated at 72 h in the SI + AG group, as compared with the SI + S group at 72 h (J-L). Scale bar =20.0 μm.

Mentions: Expression of NKCC1 was observed in some GFAP-expressing cells in the external plexiform layer, mitral cell layer, and internal plexiform layer (Figure 8). In the C group (Figure 8A,B), moderate NKCC1 immunofluorescence was detected in the soma of occasional astrocytes (Figure 8C). In the SI + S group at 24 and 72 h, both GFAP and NKCC1 immunoreactivity were markedly increased (Figure 8D-I), notably at 24 h. In the SI + AG group at 72 h, both GFAP and NKCC1 immunofluorescence were decreased, as compared with the SI + S group at the same time point (Figure 8J-L).Figure 8


Combustion smoke-induced inflammation in the olfactory bulb of adult rats.

Zou YY, Yuan Y, Kan EM, Lu J, Ling EA - J Neuroinflammation (2014)

NKCC1 (red) and GFAP (green) immunopositive astrocytes in the bulb tissue of the control group (A-C), the SI + S group at 24 and 72 h (D-I), and the SI + AG group at 72 h (J-L). In the C group, only sporadic astrocytes exhibit moderate NKCC1 immunofluorescence. In the SI + S group, it is evidently enhanced in hypertrophic astrocytes at 24 and 72 h (D-I), being more pronounced at 24 h (E). Colocalized expression of NKCC1 with GFAP immunoreactive astrocytes (arrows) can be seen in C, F, I and L. Immunoreactivity for both NKCC1 and GFAP is attenuated at 72 h in the SI + AG group, as compared with the SI + S group at 72 h (J-L). Scale bar =20.0 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4197300&req=5

Fig8: NKCC1 (red) and GFAP (green) immunopositive astrocytes in the bulb tissue of the control group (A-C), the SI + S group at 24 and 72 h (D-I), and the SI + AG group at 72 h (J-L). In the C group, only sporadic astrocytes exhibit moderate NKCC1 immunofluorescence. In the SI + S group, it is evidently enhanced in hypertrophic astrocytes at 24 and 72 h (D-I), being more pronounced at 24 h (E). Colocalized expression of NKCC1 with GFAP immunoreactive astrocytes (arrows) can be seen in C, F, I and L. Immunoreactivity for both NKCC1 and GFAP is attenuated at 72 h in the SI + AG group, as compared with the SI + S group at 72 h (J-L). Scale bar =20.0 μm.
Mentions: Expression of NKCC1 was observed in some GFAP-expressing cells in the external plexiform layer, mitral cell layer, and internal plexiform layer (Figure 8). In the C group (Figure 8A,B), moderate NKCC1 immunofluorescence was detected in the soma of occasional astrocytes (Figure 8C). In the SI + S group at 24 and 72 h, both GFAP and NKCC1 immunoreactivity were markedly increased (Figure 8D-I), notably at 24 h. In the SI + AG group at 72 h, both GFAP and NKCC1 immunofluorescence were decreased, as compared with the SI + S group at the same time point (Figure 8J-L).Figure 8

Bottom Line: The results showed a significant increase in VEGF, iNOS, eNOS, nNOS, NKCC1, and GFAP expression in the bulb tissues, with corresponding increases in inflammatory cytokines and chemokines after smoke inhalation.Concurrent to this was a drastic increase in AQP4 expression and RITC permeability.This was coupled with a significant reduction in incidence of TUNEL + cells that was not altered with administration of L-NG-nitroarginine methyl ester (L-NAME).

View Article: PubMed Central - PubMed

ABSTRACT

Background: The damaging effect of combustion smoke inhalation on the lung is widely reported but information on its effects on the olfactory bulb is lacking. This study sought to determine the effects of smoke inhalation on the olfactory bulb, whose afferent input neurons in the nasal mucosa are directly exposed to external stimuli, such as smoke.

Methods: Adult male Sprague-Dawley rats were subjected to combustion smoke inhalation and sacrificed at different time points. Changes in olfactory bulb proteins including vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), Na+-K+-Cl- cotransporter 1 (NKCC1), glial fibrillary acidic protein (GFAP), and aquaporin-4 (AQP4) were evaluated by Western blot analysis. In addition, ELISA was conducted for cytokine and chemokine levels, and double immunofluorescence labeling was carried out for GFAP/VEGF, GFAP/AQP4, NeuN/nNOS, GFAP/NKCC1, NeuN/NKCC1, GFAP/Rhodamine isothiocyanate (RITC), and transferase dUTP nick end labeling (TUNEL). Aminoguanidine was administered to determine the effects of iNOS inhibition on the targets probed after smoke inhalation.

Results: The results showed a significant increase in VEGF, iNOS, eNOS, nNOS, NKCC1, and GFAP expression in the bulb tissues, with corresponding increases in inflammatory cytokines and chemokines after smoke inhalation. Concurrent to this was a drastic increase in AQP4 expression and RITC permeability. Aminoguanidine administration decreased the expression of iNOS and RITC extravasation after smoke inhalation. This was coupled with a significant reduction in incidence of TUNEL + cells that was not altered with administration of L-NG-nitroarginine methyl ester (L-NAME).

Conclusions: These findings suggest that the upregulation of iNOS in response to smoke inhalation plays a major role in the olfactory bulb inflammatory pathophysiology, along with a concomitant increase in pro-inflammatory molecules, vascular permeability, and edema. Overall, these findings indicate that the olfactory bulb is vulnerable to smoke inhalation.

Show MeSH
Related in: MedlinePlus