The Neuro-Protective Lifestyle

Your Astrocytes To The Rescue!

Posted on 08. Nov, 2008 by Kerry Friesen, M.D. in Brain Myths Busted, Neuro-Hero

ASTROCYTES: NOT JUST FILLER ANYMORE

For decades, neurons have gotten all the glory. They’re smart, sexy, sleek, sophisticated, lightning fast and extremely elitist since they make up only 10% of the brain.

Sandwiched between 100 billion neurons—more or less—you’ll find 10 times as many “glial” cells, (from the latin for glue). Astrocytes are the most abundant type of glial cell and for decades were thought to do little more than provide structural support for our massive neural network and clean-up cellular debris when necessary.

ASTROCYTES, NEUROGENESIS AND SYNAPTIC PLASTICITY

Astrocytes may in fact hold the neurochemical key to two fundamental areas of continued brain growth—neurogenesis (the creation of a new neuron) and synaptic plasticity (the strengthening of neuron to neuron connectivity).

Here’s how it works.

Neurons manufacture two different forms of the same growth factor known as BDNF (brain-derived neurotrophic factor). Synaptic transmission and connectivity (read learning and memory) are influenced by the type of BDNF present. Previously it was thought that neurons were responsible for the entire process. It appears now that astrocytes are capable of fine-tuning synaptic plasticity and thus enhance learning and memory by regulating the amount of BDNF present in neuronal synapses.

REGENERATION AND REPAIR

In keeping with the sub-merged super-hero metaphor (hint: it’s the title of the post), astrocytes apparently possess free-radical scavenging and metal ion chelating properties.

When astrocytes detect neuronal injury, they respond by overproducing metallothionein (MT). MT as it turns out is a powerful neuroprotective agent that is capable of preventing the oxidative stress and subsequent neuroinflammation caused by free radicals and thought to be the causative factor for most neurodegenerative disorders.

ASTROCYTES HAVE AN EVIL SIDE

For all the good they do, astrocytes still can go bad. David Welch was diagnosed with a low-grade astrocytoma in December 2004. While low-grade astrocytomas represent only 6% of all brain tumor and ordinarily have an expected 90% 5 year survival—David’s medical course has taken a different turn.

Check out 38 LEMON, for an emotionally stirring and poignant look inside David’s mind as he chronicles* his experience with the evil side of an astrocyte that just won’t go away….

*WARNING: David’s brain surgery video is not for the squeamish.
Link to the National Cancer Institute: Brain Tumor Database

Tags: astrocytes, astrocytoma, BDNF, brain tumor, glial cells, learning, LTP, memory, neurogenesis, neuroglia, synaptic plasticity