Limits...
NTRK2 expression levels are reduced in laser captured pyramidal neurons from the anterior cingulate cortex in males with autism spectrum disorder.

Chandley MJ, Crawford JD, Szebeni A, Szebeni K, Ordway GA - Mol Autism (2015)

Bottom Line: The level of NTRK2 expression was robustly and significantly lower in pyramidal neurons from ASD donors as compared to typically developing donors.Levels of expression of GRIN1, GRM8, SLC1A1, and GRIP1 were modestly lower in pyramidal neurons from ASD donors, but statistical significance for these latter genes did not survive correction for multiple comparisons.No significant expression differences of any genes were found in astrocytes laser captured from the same neocortical area.

View Article: PubMed Central - PubMed

Affiliation: Department of Health Sciences, College of Public Health, East Tennessee State University, P.O. Box 70673, Johnson City, TN 37614 USA.

ABSTRACT

Background: The anterior cingulate cortex (ACC) is a brain area involved in modulating behavior associated with social interaction, disruption of which is a core feature of autism spectrum disorder (ASD). Functional brain imaging studies demonstrate abnormalities of the ACC in ASD as compared to typically developing control patients. However, little is known regarding the cellular basis of these functional deficits in ASD. Pyramidal neurons in the ACC are excitatory glutamatergic neurons and key cellular mediators of the neural output of the ACC. This study was designed to investigate the potential role of ACC pyramidal neurons in ASD brain pathology.

Methods: Postmortem ACC tissue from carefully matched ASD and typically developing control donors was obtained from two national brain collections. Pyramidal neurons and surrounding astrocytes were separately collected from layer III of the ACC by laser capture microdissection. Isolated RNA was subjected to reverse transcription and endpoint PCR to determine gene expression levels for 16 synaptic genes relevant to glutamatergic neurotransmission. Cells were also collected from the prefrontal cortex (Brodmann area 10) to examine those genes demonstrating differences in expression in the ACC comparing typically developing and ASD donors.

Results: The level of NTRK2 expression was robustly and significantly lower in pyramidal neurons from ASD donors as compared to typically developing donors. Levels of expression of GRIN1, GRM8, SLC1A1, and GRIP1 were modestly lower in pyramidal neurons from ASD donors, but statistical significance for these latter genes did not survive correction for multiple comparisons. No significant expression differences of any genes were found in astrocytes laser captured from the same neocortical area. In addition, expression levels of NTRK2 and other synaptic genes were normal in pyramidal neurons laser captured from the prefrontal cortex.

Conclusions: These studies demonstrate a unique pathology of neocortical pyramidal neurons of the ACC in ASD. NTRK2 encodes the tropomyosin receptor kinase B (TrkB), transmission through which neurotrophic factors modify differentiation, plasticity, and synaptic transmission. Reduced pyramidal neuron NTRK2 expression in the ACC could thereby contribute to abnormal neuronal activity and disrupt social behavior mediated by this brain region.

No MeSH data available.


Related in: MedlinePlus

Ratio of reference gene expression levels. Gene expression was measured for GAPDH and RNA18S1 in typically developing control donors (open symbols) and ASD donors (closed symbols). The ratio of gene expression between the two reference genes was compared for control and ASD subjects for BA24 neurons and astrocytes and BA10 neurons to ensure that the reference genes had stable expression levels between the groups. No statistically significant differences were observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4440594&req=5

Fig6: Ratio of reference gene expression levels. Gene expression was measured for GAPDH and RNA18S1 in typically developing control donors (open symbols) and ASD donors (closed symbols). The ratio of gene expression between the two reference genes was compared for control and ASD subjects for BA24 neurons and astrocytes and BA10 neurons to ensure that the reference genes had stable expression levels between the groups. No statistically significant differences were observed.

Mentions: It should be noted that we wished to screen multiple brain regions for these gene expression changes to determine the extent to which they occurred in the brain. Because LCM is time-intensive and expensive, we attempted to measure SLC1A1, GRIP1, and NTRK2 expression in RNA isolated from homogenates of ACC. However, we were unable to detect any differences in expression of these genes in RNA isolates from homogenates of ACC, using tissues collected from seven of the eight ASD - control donor pairs that were used for the LCM study above (FigureĀ 6). No significant difference was found for the ratios of expression of the reference genes GAPDH and TATA from the homogenate punch samples when comparing ASD and control donors (Additional file 6; t = 0.19, P = 0.86).Figure 6


NTRK2 expression levels are reduced in laser captured pyramidal neurons from the anterior cingulate cortex in males with autism spectrum disorder.

Chandley MJ, Crawford JD, Szebeni A, Szebeni K, Ordway GA - Mol Autism (2015)

Ratio of reference gene expression levels. Gene expression was measured for GAPDH and RNA18S1 in typically developing control donors (open symbols) and ASD donors (closed symbols). The ratio of gene expression between the two reference genes was compared for control and ASD subjects for BA24 neurons and astrocytes and BA10 neurons to ensure that the reference genes had stable expression levels between the groups. No statistically significant differences were observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4440594&req=5

Fig6: Ratio of reference gene expression levels. Gene expression was measured for GAPDH and RNA18S1 in typically developing control donors (open symbols) and ASD donors (closed symbols). The ratio of gene expression between the two reference genes was compared for control and ASD subjects for BA24 neurons and astrocytes and BA10 neurons to ensure that the reference genes had stable expression levels between the groups. No statistically significant differences were observed.
Mentions: It should be noted that we wished to screen multiple brain regions for these gene expression changes to determine the extent to which they occurred in the brain. Because LCM is time-intensive and expensive, we attempted to measure SLC1A1, GRIP1, and NTRK2 expression in RNA isolated from homogenates of ACC. However, we were unable to detect any differences in expression of these genes in RNA isolates from homogenates of ACC, using tissues collected from seven of the eight ASD - control donor pairs that were used for the LCM study above (FigureĀ 6). No significant difference was found for the ratios of expression of the reference genes GAPDH and TATA from the homogenate punch samples when comparing ASD and control donors (Additional file 6; t = 0.19, P = 0.86).Figure 6

Bottom Line: The level of NTRK2 expression was robustly and significantly lower in pyramidal neurons from ASD donors as compared to typically developing donors.Levels of expression of GRIN1, GRM8, SLC1A1, and GRIP1 were modestly lower in pyramidal neurons from ASD donors, but statistical significance for these latter genes did not survive correction for multiple comparisons.No significant expression differences of any genes were found in astrocytes laser captured from the same neocortical area.

View Article: PubMed Central - PubMed

Affiliation: Department of Health Sciences, College of Public Health, East Tennessee State University, P.O. Box 70673, Johnson City, TN 37614 USA.

ABSTRACT

Background: The anterior cingulate cortex (ACC) is a brain area involved in modulating behavior associated with social interaction, disruption of which is a core feature of autism spectrum disorder (ASD). Functional brain imaging studies demonstrate abnormalities of the ACC in ASD as compared to typically developing control patients. However, little is known regarding the cellular basis of these functional deficits in ASD. Pyramidal neurons in the ACC are excitatory glutamatergic neurons and key cellular mediators of the neural output of the ACC. This study was designed to investigate the potential role of ACC pyramidal neurons in ASD brain pathology.

Methods: Postmortem ACC tissue from carefully matched ASD and typically developing control donors was obtained from two national brain collections. Pyramidal neurons and surrounding astrocytes were separately collected from layer III of the ACC by laser capture microdissection. Isolated RNA was subjected to reverse transcription and endpoint PCR to determine gene expression levels for 16 synaptic genes relevant to glutamatergic neurotransmission. Cells were also collected from the prefrontal cortex (Brodmann area 10) to examine those genes demonstrating differences in expression in the ACC comparing typically developing and ASD donors.

Results: The level of NTRK2 expression was robustly and significantly lower in pyramidal neurons from ASD donors as compared to typically developing donors. Levels of expression of GRIN1, GRM8, SLC1A1, and GRIP1 were modestly lower in pyramidal neurons from ASD donors, but statistical significance for these latter genes did not survive correction for multiple comparisons. No significant expression differences of any genes were found in astrocytes laser captured from the same neocortical area. In addition, expression levels of NTRK2 and other synaptic genes were normal in pyramidal neurons laser captured from the prefrontal cortex.

Conclusions: These studies demonstrate a unique pathology of neocortical pyramidal neurons of the ACC in ASD. NTRK2 encodes the tropomyosin receptor kinase B (TrkB), transmission through which neurotrophic factors modify differentiation, plasticity, and synaptic transmission. Reduced pyramidal neuron NTRK2 expression in the ACC could thereby contribute to abnormal neuronal activity and disrupt social behavior mediated by this brain region.

No MeSH data available.


Related in: MedlinePlus