|
Sleep
and Memory
George O, Vallee M, Le Moal M, Mayo W. Neurosteroids
and cholinergic systems: implications for sleep and
cognitive processes and potential role of age-related
changes Neurosteroids and cholinergic systems:
implications for sleep and cognitive processes and
potential role of age-related changes.
Psychopharmacology (Berl). 2006 Jan 17;:1-12
Rationale: The neurosteroids pregnenolone sulfate (PREGS),
dehydroepiandrosterone sulfate (DHEAS) and
allopregnanolone (3alpha,5alpha THPROG) have been
implicated as powerful modulators of memory processes
and sleep states in young and aged subjects with memory
impairment. As these processes depend on the integrity
of cholinergic systems, a specific effect of
neurosteroids on these systems may account for their
effects on sleep and memory.
Objective: To review the evidence for a specific and
differential effect of neurosteroids on cholinergic
systems.
Conclusions: The specific modulation of basal forebrain
and brainstem cholinergic systems by neurosteroids may
account for the effects of these compounds on sleep and
memory processes. To improve our understanding of the
role of neurosteroids in cholinergic systems during
normal and pathological aging, we need to determine
whether there is specific regionalization of
neurosteroids, and we need to investigate the
relationship between neurosteroid concentrations in
cholinergic nuclei and age-related sleep and memory
impairments.
|
|
Alzheimer's
Neurosteroid quantification in human brain regions:
comparison between Alzheimer's and nondemented patients.
Weill-Engerer S, David
JP, Sazdovitch V, Liere P, Eychenne B, Pianos A,
Schumacher M, Delacourte A, Baulieu EE, Akwa
Y.Neurosteroid quantification in human brain regions:
comparison between Alzheimer's and nondemented
patients.J Clin Endocrinol Metab. 2002
Nov;87(11):5138-43
Abstract: "...To
investigate the physiopathological significance of
neurosteroids in Alzheimer's disease (AD), we compared
the concentrations of pregnenolone, pregnenolone sulfate
(PREGS), dehydroepiandrosterone, dehydroepiandrosterone
sulfate (DHEAS), progesterone, and allopregnanolone...in
individual brain regions of AD patients and aged
nondemented controls, including hippocampus, amygdala,
frontal cortex, striatum, hypothalamus, and cerebellum.
A general trend toward
decreased levels of all steroids was observed in all AD
patients' brain regions compared with controls: PREGS
and DHEAS were significantly lower in the striatum and
cerebellum, and DHEAS was also significantly reduced in
the hypothalamus. A significant negative correlation was
found between the levels of cortical beta-amyloid
peptides and those of PREGS in the striatum and
cerebellum and between the levels of phosphorylated tau
proteins and DHEAS in the hypothalamus. This study
provides reference values for steroid concentrations
determined by gas chromatography-mass spectrometry in
various regions of the aged human brain. High levels of
key proteins implicated in the formation of plaques and
neurofibrillary tangles were correlated with decreased
brain levels of PREGS and DHEAS, suggesting a possible
neuroprotective role of these neurosteroids in AD.” |
