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Studies of olfactory system neural plasticity: the contribution of the unilateral naris occlusion technique.

Coppola DM - Neural Plast. (2012)

Bottom Line: Early experiments emphasized naris occlusion's deleterious and age-critical effects.More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation.This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Randolph Macon College, Ashland, VA 23005, USA. dcoppola@rmc.edu

ABSTRACT
Unilateral naris occlusion has long been the method of choice for effecting stimulus deprivation in studies of olfactory plasticity. A significant body of literature speaks to the myriad consequences of this manipulation on the ipsilateral olfactory pathway. Early experiments emphasized naris occlusion's deleterious and age-critical effects. More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation. Despite the abundance of empirical data, a theoretical framework in which to understand the many sequelae of naris occlusion on olfaction has been elusive. This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

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Related in: MedlinePlus

Microarray analysis of the effects of early postnatal UNO on olfactory bulb transcriptome of young adult mice. (a) Expression profile of 103 genes from the >20,000 total on the chip that met arbitrary significance criteria (2.25-fold up, or 2.25-fold down, with P < 0.01). Tissue source is shown on bottom axis. Note that there were three technical replicates within each of three biological replicates (subscript numbers). Color represents expression value with red, upregulation and green, downregulation. Dendrograms based on expression values show clustering genes (left) and samples (right), respectively. Note large number of up- and downregulated genes in both occluded and open (nonoccluded) bulb with normal bulb showing intermediate expression of most genes. (b) Volcano plot of 16,456 genes detected by the array for the comparison of occluded versus open olfactory bulb in UNO mice. Transcript abundance (log2) is plotted on the abscissa. Statistical significance (log10) is plotted on the ordinate. Genes shown in red meet a 2-fold and P < 0.01 criterion. Note that there are more upregulated genes (+) than downregulated genes (−) on occluded side.
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fig3: Microarray analysis of the effects of early postnatal UNO on olfactory bulb transcriptome of young adult mice. (a) Expression profile of 103 genes from the >20,000 total on the chip that met arbitrary significance criteria (2.25-fold up, or 2.25-fold down, with P < 0.01). Tissue source is shown on bottom axis. Note that there were three technical replicates within each of three biological replicates (subscript numbers). Color represents expression value with red, upregulation and green, downregulation. Dendrograms based on expression values show clustering genes (left) and samples (right), respectively. Note large number of up- and downregulated genes in both occluded and open (nonoccluded) bulb with normal bulb showing intermediate expression of most genes. (b) Volcano plot of 16,456 genes detected by the array for the comparison of occluded versus open olfactory bulb in UNO mice. Transcript abundance (log2) is plotted on the abscissa. Statistical significance (log10) is plotted on the ordinate. Genes shown in red meet a 2-fold and P < 0.01 criterion. Note that there are more upregulated genes (+) than downregulated genes (−) on occluded side.

Mentions: Another implicit assumption of the UNO technique is that its effects are systemically benign and limited to olfaction. However, investigators have repeatedly shown that animals grow at a slower rate after UNO compared to controls (e.g., [12, 88]). In contrast to deprivation directed at the eye or the ear, the nasal cavity has a number of functions besides olfaction not least respiration. Local reductions in oxygen, increases in carbon dioxide, and the aforementioned protection from drying, irritants, and microbes could all be factors underlying some of the effects of UNO. To this point and as noted previously, turbinate morphology is abnormal on the occluded side of young adult mice after early postnatal UNO, an effect unlikely to be related to odor deprivation [51]. Finally, we have recently compared the transcriptomes of ipsilateral and contralateral UNO mice to those of untreated mice ([92]; Figure 3). A number of genes, seemingly unrelated to olfaction, are regulated in the occluded-side mucosa and bulb, casting further doubt on the specificity assumption.


Studies of olfactory system neural plasticity: the contribution of the unilateral naris occlusion technique.

Coppola DM - Neural Plast. (2012)

Microarray analysis of the effects of early postnatal UNO on olfactory bulb transcriptome of young adult mice. (a) Expression profile of 103 genes from the >20,000 total on the chip that met arbitrary significance criteria (2.25-fold up, or 2.25-fold down, with P < 0.01). Tissue source is shown on bottom axis. Note that there were three technical replicates within each of three biological replicates (subscript numbers). Color represents expression value with red, upregulation and green, downregulation. Dendrograms based on expression values show clustering genes (left) and samples (right), respectively. Note large number of up- and downregulated genes in both occluded and open (nonoccluded) bulb with normal bulb showing intermediate expression of most genes. (b) Volcano plot of 16,456 genes detected by the array for the comparison of occluded versus open olfactory bulb in UNO mice. Transcript abundance (log2) is plotted on the abscissa. Statistical significance (log10) is plotted on the ordinate. Genes shown in red meet a 2-fold and P < 0.01 criterion. Note that there are more upregulated genes (+) than downregulated genes (−) on occluded side.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3368527&req=5

fig3: Microarray analysis of the effects of early postnatal UNO on olfactory bulb transcriptome of young adult mice. (a) Expression profile of 103 genes from the >20,000 total on the chip that met arbitrary significance criteria (2.25-fold up, or 2.25-fold down, with P < 0.01). Tissue source is shown on bottom axis. Note that there were three technical replicates within each of three biological replicates (subscript numbers). Color represents expression value with red, upregulation and green, downregulation. Dendrograms based on expression values show clustering genes (left) and samples (right), respectively. Note large number of up- and downregulated genes in both occluded and open (nonoccluded) bulb with normal bulb showing intermediate expression of most genes. (b) Volcano plot of 16,456 genes detected by the array for the comparison of occluded versus open olfactory bulb in UNO mice. Transcript abundance (log2) is plotted on the abscissa. Statistical significance (log10) is plotted on the ordinate. Genes shown in red meet a 2-fold and P < 0.01 criterion. Note that there are more upregulated genes (+) than downregulated genes (−) on occluded side.
Mentions: Another implicit assumption of the UNO technique is that its effects are systemically benign and limited to olfaction. However, investigators have repeatedly shown that animals grow at a slower rate after UNO compared to controls (e.g., [12, 88]). In contrast to deprivation directed at the eye or the ear, the nasal cavity has a number of functions besides olfaction not least respiration. Local reductions in oxygen, increases in carbon dioxide, and the aforementioned protection from drying, irritants, and microbes could all be factors underlying some of the effects of UNO. To this point and as noted previously, turbinate morphology is abnormal on the occluded side of young adult mice after early postnatal UNO, an effect unlikely to be related to odor deprivation [51]. Finally, we have recently compared the transcriptomes of ipsilateral and contralateral UNO mice to those of untreated mice ([92]; Figure 3). A number of genes, seemingly unrelated to olfaction, are regulated in the occluded-side mucosa and bulb, casting further doubt on the specificity assumption.

Bottom Line: Early experiments emphasized naris occlusion's deleterious and age-critical effects.More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation.This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Randolph Macon College, Ashland, VA 23005, USA. dcoppola@rmc.edu

ABSTRACT
Unilateral naris occlusion has long been the method of choice for effecting stimulus deprivation in studies of olfactory plasticity. A significant body of literature speaks to the myriad consequences of this manipulation on the ipsilateral olfactory pathway. Early experiments emphasized naris occlusion's deleterious and age-critical effects. More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation. Despite the abundance of empirical data, a theoretical framework in which to understand the many sequelae of naris occlusion on olfaction has been elusive. This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

Show MeSH
Related in: MedlinePlus