The Effect of Sensory Deprivation on the

Density of M1 Microglia in the Mouse Barrel Cortex

Yuhong WangThe Bronx High School of Science

Cells of The Central Nervous System

Neurons• Processes, transmits

information

Glia• Maintains

homeostasis• Includes:• Astrocytes• Schwann Cells • Microglia

Microglia • Resident macrophage of the Central

Nervous System• Constantly surveying its environment • Processes engage in phagocytosis of

pathogens and debris• Releases various cytokines to maintain

homeostasis in the CNS

The Barrel Cortex • In the present study, we are looking at the

presence of microglial cells in the barrel cortex • Barrel Cortex

o A region of the somatosensory cortex that processes information from a rodent’s whiskers

o Organized topographically; Each whisker is represented by a discrete aggregation of neurons called a barrel

Barrel Cortex

The Effect of Sensory Deprivation

• Trimming a rodent’s whiskers for the first postnatal month has been shown to result in neuronal remodeling

But, it seems microglia are also impacted by sensory deprivation

How So?

Previous Studies • Following trimming,

there is a significant increase in cell body area and a significant decrease in process length of microglia

The fact that sensory deprivation leads to a change in microglial morphology suggests that microglia are changing from a resting state phenotype to an activated phenotype

Activated Microglia • Expresses 2 distinct phenotypes

o M1 phenotype, or classically activated microglia, are neurotoxic, as they release reactive oxygen species and proinflammatory cytokines

o M2 phenotype, or alternatively activated microglia, are neuroprotective, as they block proinflammatory responses and instead produce high levels of anti-inflammatory cytokines and neurotropic factors.

Problem: How are M1 Microglia Impacted by Sensory Derivation?

Due to the previously described structural arrangements in the barrel cortex following trimming, we aim to determine if sensory deprivation will have an significant impact on the density of M1 microglia.

Trimming and Perfusion

• Sensory deprivation was achieved in mice by bilaterally trimming whiskers every other day for 31 days, starting from birth. Some mice were allocated to the p60 and p90 whisker regrow group in order to prove that microglial remodeling occurs in the first 30 days of development.

• There were untrimmed mice in each group that served as control

• Respective mice were perfused on the p31, p61, and p91 days using saline and 4% paraformaldehyde. Brains were post-fixed for 24 hours in 4% paraformaldehyde.

Sectioning and Staining

• Brains were sectioned into 50 μm slices using a vibratome

• Brain sections were immunohistochemically stained for microglia using primary antibody Iba-1

• Sections were double stained with MHC-II antibody in order to detect microglia expressing the M1 phenotype.

Imaging and Analysis • Slices were mounted using 0.01M

phosphate buffer saline medium and cover slipped• Slides were imaged using confocal

microscopy and image stacks will be analyzed using computer assisted program Neurolucida 8.0 to determine the quantity and distribution of M1 microglia.

Iba-1 Rhodamine Staining

Stains for all microglial cells

MHC-II FITC Staining

Stains for all microglia expressing the M1 phenotype

FITC, Rhodamine overlap

The overlap shows the number of M1 microglia (yellow) and the number that is not expressing that phenotype (remains red)

Results

IBA + MHCII+ IBA +Sensory Deprived Control

MHCII+

Cell Type

Nu

mb

er o

f C

ells

per

100

m3

0

5

10

15

20

25

30

Number of Cells expressing the M1 phenotype in the sensory deprived and control

Pe

rcen

tag

e M

HC

II+

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Sensory Deprived Control

Sensory Deprivation does not seem to have an effect on M1 expression of microglial cells

The percentage of microglia stained MHC-II (M1 phenotype)

Conclusions • Most microglia in the mouse barrel cortex

expresses the M1 phenotype as opposed to M2

• Sensory deprivation did not have a significant impact on the density of cells expressing M1 phenotype, therefore our hypothesis was proven wrong

Future Directions• M2 microglia plays just as an

important role as M1 microglia does in neuroplasticity. Future experiments should characterize the effect of sensory deprivation on the distribution of M2 microglial cells.

Acknowledgements • This research was supported by the City

University of New York at Queens College• Thanks to Dr.Joshua Brumberg, Racheli

Wercberger and Zissy Turner for their contribution and guidance.