sleep----> cholesterol synthesis in CNS

[Guest guest]

The benefits of sleep on the mind might be due to increased cholesterol

synthesis: (One more cheer for cholesterol! :-) )

" Finally, sleep-related transcripts also code for enzymes involved in the

synthesis and trasnport of cholesterol, a major constituent of myelin and other

membranes (thiolase, 3-hydroxy-3-mehtylglutaryl--Coenzyme A synthase, squalene

synthase, lanosterol 14 alpha-demethylase). In agreement with our results,

studies in flies and mice have found that the expression of several genes

related to the synthesis of cholesterol (Ceriani et al, 2002; Panda et al.,

2002) and to synaptic vesicle recycling (Claridge-Cyhang et al., 2001) peaks

during the resting phase. Since we found no evidence that transcripts related

to cholesterol synthesis and membrane trafficking were modulated by day and

night independently of behavrioaral state (data not shown), it may be that sleep

provides especially favorable conditions for these cellular processes. Sleep is

especially abundant early in life at a time in which synaptogenesis and

myelinization are prominent, and it appears to be important for circuit

formmation and plasticity ( et al., 2001; Shaffery et al., 2002) . Recent

evidence shows that glia-derived cholesterol may be the limiting factor for

synapse formation and maintenance (Mauch et al., 2001). Thus, the association

between sleep and membrane trafficking, cholesterol synthesis, protein

synthesis, and neural plasticity may not be unrelated. "

-- Cirelli, et al., " Extensive and Divergent Effects of Sleep and Wakefulness on

Brain Gene Expression " , _Neuron_: Volume 41, No 1, January 8, 2004.

Just in case it isn't clear, when they say cholesterol synthesis is dependent on

behavioral state, they mean that it is modulated NOT by the circadian rhythm but

by sleep itself.

Chris