Physiological Reviews,
Journal Year:
2021,
Volume and Issue:
102(2), P. 1025 - 1151
Published: May 5, 2021
The
brain
harbors
a
unique
ability
to,
figuratively
speaking,
shift
its
gears.
During
wakefulness,
the
is
geared
fully
toward
processing
information
and
behaving,
while
homeostatic
functions
predominate
during
sleep.
blood-brain
barrier
establishes
stable
environment
that
optimal
for
neuronal
function,
yet
imposes
physiological
problem;
transcapillary
filtration
forms
extracellular
fluid
in
other
organs
reduced
to
minimum
brain.
Consequently,
depends
on
special
[the
cerebrospinal
(CSF)]
flushed
into
along
perivascular
spaces
created
by
astrocytic
vascular
endfeet.
We
describe
this
pathway,
coined
term
glymphatic
system,
based
dependency
endfeet
their
adluminal
expression
of
aquaporin-4
water
channels
facing
CSF-filled
spaces.
Glymphatic
clearance
potentially
harmful
metabolic
or
protein
waste
products,
such
as
amyloid-β,
primarily
active
sleep,
when
drivers,
cardiac
cycle,
respiration,
slow
vasomotion,
together
efficiently
propel
CSF
inflow
periarterial
brain's
space
contains
an
abundance
proteoglycans
hyaluronan,
which
provide
low-resistance
hydraulic
conduit
rapidly
can
expand
shrink
sleep-wake
cycle.
system
brain,
meets
requisites
maintain
homeostasis
similar
peripheral
organs,
considering
blood-brain-barrier
paths
formation
egress
CSF.
Science,
Journal Year:
2013,
Volume and Issue:
342(6156), P. 373 - 377
Published: Oct. 17, 2013
Taking
Out
the
Trash
The
purpose
of
sleep
remains
mysterious.
Using
state-of-the-art
in
vivo
two-photon
imaging
to
directly
compare
two
arousal
states
same
mouse,
Xie
et
al.
(p.
373
;
see
Perspective
by
Herculano-Houzel
)
found
that
metabolic
waste
products
neural
activity
were
cleared
out
sleeping
brain
at
a
faster
rate
than
during
awake
state.
This
finding
suggests
mechanistic
explanation
for
how
serves
restorative
function,
addition
its
well-described
effects
on
memory
consolidation.
Physiological Reviews,
Journal Year:
2017,
Volume and Issue:
98(1), P. 239 - 389
Published: Dec. 24, 2017
Astrocytes
are
neural
cells
of
ectodermal,
neuroepithelial
origin
that
provide
for
homeostasis
and
defense
the
central
nervous
system
(CNS).
highly
heterogeneous
in
morphological
appearance;
they
express
a
multitude
receptors,
channels,
membrane
transporters.
This
complement
underlies
their
remarkable
adaptive
plasticity
defines
functional
maintenance
CNS
development
aging.
tightly
integrated
into
networks
act
within
context
tissue;
astrocytes
control
at
all
levels
organization
from
molecular
to
whole
organ.
Journal of Neural Transmission,
Journal Year:
2014,
Volume and Issue:
121(8), P. 799 - 817
Published: Feb. 28, 2014
Glutamate
is
the
most
abundant
free
amino
acid
in
brain
and
at
crossroad
between
multiple
metabolic
pathways.
Considering
this,
it
was
a
surprise
to
discover
that
glutamate
has
excitatory
effects
on
nerve
cells,
can
excite
cells
their
death
process
now
referred
as
"excitotoxicity".
This
effect
due
receptors
present
surface
of
cells.
Powerful
uptake
systems
(glutamate
transporters)
prevent
excessive
activation
these
by
continuously
removing
from
extracellular
fluid
brain.
Further,
blood–brain
barrier
shields
blood.
The
highest
concentrations
are
found
synaptic
vesicles
terminals
where
be
released
exocytosis.
In
fact,
major
neurotransmitter
mammalian
central
nervous
system.
It
took,
however,
long
time
realize
that.
review
provides
brief
historical
description,
gives
short
overview
transmitter
healthy
brain,
comments
so-called
glutamate–glutamine
cycle.
transporters
responsible
for
removal
described
some
detail.
Fluids and Barriers of the CNS,
Journal Year:
2014,
Volume and Issue:
11(1), P. 10 - 10
Published: Jan. 1, 2014
According
to
the
traditional
understanding
of
cerebrospinal
fluid
(CSF)
physiology,
majority
CSF
is
produced
by
choroid
plexus,
circulates
through
ventricles,
cisterns,
and
subarachnoid
space
be
absorbed
into
blood
arachnoid
villi.
This
review
surveys
key
developments
leading
concept.
Challenging
this
concept
are
novel
insights
utilizing
molecular
cellular
biology
as
well
neuroimaging,
which
indicate
that
physiology
may
much
more
complex
than
previously
believed.
The
circulation
comprises
not
only
a
directed
flow
CSF,
but
in
addition
pulsatile
fro
movement
throughout
entire
brain
with
local
exchange
between
blood,
interstitial
fluid,
CSF.
Astrocytes,
aquaporins,
other
membrane
transporters
elements
water
homeostasis.
A
continuous
bidirectional
at
barrier
produces
rates,
exceed
choroidal
production
rate
far.
around
vessels
penetrating
from
Virchow
Robin
spaces
provides
both
drainage
pathway
for
clearance
waste
molecules
site
interaction
systemic
immune
system
brain.
Important
physiological
functions,
example
regeneration
during
sleep,
depend
on
circulation.
Proceedings of the National Academy of Sciences,
Journal Year:
2018,
Volume and Issue:
115(17), P. 4483 - 4488
Published: April 9, 2018
Significance
There
has
been
an
emerging
interest
in
sleep
and
its
association
with
β-amyloid
burden
as
a
risk
factor
for
Alzheimer’s
disease.
Despite
the
evidence
that
acute
deprivation
elevates
levels
mouse
interstitial
fluid
human
cerebrospinal
fluid,
not
much
is
known
about
impact
of
on
brain.
Using
positron
emission
tomography,
here
we
show
impacts
brain
regions
have
implicated
Our
observations
provide
preliminary
negative
effect
Science,
Journal Year:
2020,
Volume and Issue:
370(6512), P. 50 - 56
Published: Oct. 2, 2020
Sleep
is
evolutionarily
conserved
across
all
species,
and
impaired
sleep
a
common
trait
of
the
diseased
brain.
quality
decreases
as
we
age,
disruption
regular
architecture
frequent
antecedent
to
onset
dementia
in
neurodegenerative
diseases.
The
glymphatic
system,
which
clears
brain
protein
waste
products,
mostly
active
during
sleep.
Yet
system
degrades
with
suggesting
causal
relationship
between
disturbance
symptomatic
progression
dementias.
ties
that
bind
sleep,
aging,
clearance,
aggregation
have
shed
new
light
on
pathogenesis
broad
range
diseases,
for
failure
may
constitute
therapeutically
targetable
final
pathway.
