Tuesday, March 22, 2011

astrocytes in central nervous system regeneration

This was also referred to in the Willis lecture.
http://jrm.medicaljournals.se/article/abstract/10.2340/16501977-0084
Abstract:
Rehabilitation medicine is entering a new era, based on the knowledge that the central nervous system has a substantial capacity for repair and regeneration. This capacity is used in 3 distinct but overlapping situations: (i) routine housekeeping throughout life (i.e. taking care of normal wear-and-tear); (ii) older age, when functional reserves of various kinds are depleted, resulting in cognitive, motor, and other deficits; and (iii) contexts in which a neurological deficit reflects an acute or chronic pathological process, such as neurotrauma, stroke, or neurodegenerative disease. The positive message here is two-fold. First, some aspects of regeneration occur even in the adult and ageing brain and spinal cord, and we are starting to unravel the underlying molecular mechanisms. Secondly, novel therapeutic approaches and targets are emerging that will substantially increase the efficiency and efficacy of rehabilitation and will transform rehabilitation into a discipline focusing both on its traditional domain and on prevention, ultimately across all the age categories. This review attempts to sum up the present knowledge about an enriched environment, currently the single most efficient plasticity- and regeneration-promoting paradigm. It also summarizes research showing that astrocytes – considered only years ago merely to nurse and support neurones – are a novel and highly interesting target for regenerative strategies in the brain and spinal cord.
Picture here:http://blustein.tripod.com/Astrocytes/astrocytes.htm
What they do:Astrocytes are star shaped glial cells that perform a variety of functions in the CNS.  Astrocytes provide physical support to neurons and clean up debris within the brain.  They also provide neurons with some of the chemicals needed for proper functioning and help control the chemical composition of fluid surrounding neurons.  Finally, astrocytes play a role in providing nourishment to neurons.
In order to provide physical support for neurons astrocytes form a matrix that keep neurons in place.  In addition, this matrix serves to isolate synapses. This limits the dispersion of transmitter substances released by terminal buttons; thus aiding in the smooth transmission of neural messages.
Astrocytes also perform a process known as phagocytosis.  Phagocytosis occurs when an astrocyte contacts a piece of neural debris with its processes (arm of the astrocyte) and then pushes itself against the debris eventually engulfing and digesting it.
Astrocytes provide nourishment to neurons by 1) receiving glucose from capillaries 2) breaking the glucose down into lactate (the chemical produced during the first step of glucose metabolism) 3) releasing the lactate into the extra cellular fluid surrounding the neurons.  The neurons receive the lactate from the extra cellular fluid and transport it to their mitochondria to use it for energy.  In this process astrocytes store a small amount of glycogen, which stays on reserve for times when the metabolic rate of neurons in the area is especially high.

It does leave the question open as to how to use this knowledge to rehabilitate.

1 comment:

  1. Just a suggestion...

    If u felt inclined, i'd play around with visualisations of these things in your post, & acknowledging the body's intelligence to know exactly what to do in helping itself! Or as u go to sleep, think about all that info, what it means & drift off exploring any implications. ..using the dreamstate for its problem solving/inventive/creative capabilities, or whatever.

    For example,I at times go to sleep acknowledging magical, miraculous healing energy pervading my body & brain, & the air that i'm breathing/what i call magical chi,(anything can happen as long as it's good for me!), all that i know & all that i don't know, & thanking my body for all that it's doing....& variations on that theme....imbuing trust in the process. (I've had a hard time trusting...so say the things that i really need, as well as the things i feel ok/confident about).

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