Transcript ppt4

Neurogenesis in the
Dentate Gyrus of the
Adult Tree Shrew Is
Regulated by
Psychosocial Stress and
NMDA Receptor Activation
By
Elizabeth Gould, Bruce McEwen,
Patima Tanapat, Lisa Galea, &
Eberhard Fucha
Tree Shrew
What is ???
Tree shrews (Tupaia belangeri) are considered to
be phylogenetically between insectivores and
primates.
Neurogenesis occurs throughout life, and occurs
when new neurons and glial cells are born in the
brain.
Bromodeoxyuridine (BrdU) was used as a good
test for neurogenesis because BrdU is incorporated
into dividing cells.
Methods
Experiment 1:
The dentate gyrus of tree shrews were processed for BrdU ICC at 2
and 24 hour survival times (n = 3 for each group) after BrdU injections.
The 2 hour survival time allowed for BrdU uptake into cells synthesizing
DNA and the 24 hour survival time allowed for the completion of at least
one cell cycle by cells in S phase at the time of BrdU injection.
Experiment 2:
To determine if cells the incorporate BrdU survive and express the
neuronal marker neuron specific enolase (NSE).
BrdU injection and perfused transcardally 3 weeks later (n = 3 for each
group) after BrdU injections.
Methods Continued..
Experiment 3:
To determine if cell proliferation can be modulated by a stressful
experience.
Acute psychosocial stress in the form of active competition for an
enlarged territory and the establishment of dominant/subordinate
relationship.
The acute psychosocial stress occurred for a total of 1 hour.
The stressed group and the control unstressed group of animals were
given one BrdU injection each with a 2 hour survival time (n = 3 for
each group) after BrdU injections.
Methods Continued…
Experiment 4:
To determine if the production of cells in the dentate gyrus are affected
by NMDA receptor activation.
Animals were injected with a specific noncompetitive NMDA receptor
antagonist MK-801 or saline.
The MK-801group and the saline group of animals were given one
BrdU injection each with a 2 hour survival time (n = 3 for each group)
after BrdU injections.
this study…
The present studies were undertaken to determine
whether granule cell production and its regulation by
stressful experience and excitatory input occur in the
dentate gyrus of the adult tree shrew Tupaia
belangeri.
Data Analysis
For each brain, at least six sections were selected for
analysis from middle to caudal dentate gyrus.
For each section, cells in the dentate gyrus were
counted and the means of the data were subjected to
a Student’s t test.
Data Analysis Table
Cell Types in the
DeNtate Gyrus
Results
BrdU labeled cells were found throughout the dentate gyrus at
all levels examined (Figs 1-3).
~85% of the cells had the morphological characteristics of
granule cell precursors (round or oval), medium sized cell
bodies (Fig. 4).
The rest of the cells had the morphological characteristics of
glial cells (triangular or irregular), small sized cell bodies (Fig. 4).
Typically these cells were found (Figs. 1-4):
a. subgranular zone (sgz)
b. border of the granule cell layer (gcl)
c. hilus
Results Continued…
Quantitative Analysis revealed 2 times as many BrdU labeled
cells between 2 and 24 hour survival times after BrdU injections:
All of the cells that were labeled with BrdU and NSE were
located in the gcl (Figs. 1-3) and had the morphological
characteristics of granule neurons.
Exposure to a single episode of acute psychosocial stress that
last 1 hour resulted in a significant decrease in the density of
BrdU-labeled cells in the dentate gyrus compared to the
unstressed controls.
Treatment with the NMDA receptor antagonist MK-801 resulted
in a significant increase in the density of BrdU-labeled cells in
the dentate gyrus.
Figure 1
Figure 2
Figure 3
NMDA Receptor
Stress Related Diseases
Thank You