Posted by SLS on December 3, 2022, at 13:16:14
In reply to Antipsychotics and brain volume, posted by NKP on December 3, 2022, at 4:39:47
I dont know the biology behind the alterations in tissue activity produced by antipsychotics, but it might have to do with D2 dopamine receptor blockade reducing neurotransmission regionally.
Less DA activity = less glucose needed to be metabolized for energy.
PET = Positron Emission Tomography
Regional brain activity can be measured by using PET scans. My brain was one of the first to be imaged at the NIH. I had been an inpatient research subject. To accomplish this, PET scans use Start Trek technology <grin>. Really. Scientists measure the rate at which glucose is consumed as a measure of regional neural activity. This trick uses fluorodexyglucose as a substitute for glucose. Cells dont recognize the difference. Nevertheless, fluorodeoxyglucose provides energy to the cell in exactly the same way as normal glucose. This is where things get pretty cool. When the fluorodeoxyglucose is consumed for energy, electrons (matter) and positrons (antimatter) are liberated. When these particles collide, both disappear. They are annihilated. This annihilation event converts matter into energy in the form of gamma rays. The gamma rays liberated are detected by sensors along the inner surface of a tube, much like a MRI. Matter-Antimatter. Long live Scotty and the U.S.S. Enterprise warp engines.
,,,and Einstein. Matter / antimatter is converted into pure energy in the form of gamma rays. E=MC(2).
I dont have copies of the results of my PET scan, but they looked very much like this:
Scary.
It just so happens that the higher the rate of energy production within a brain structure, the higher the rate at which oxygen is consumed there. This is supported only by an increase in blood flow and the resulting increase in the volume of brain tissue. If, however, the activity of neurons in reduced, so is blood flow, and the resulting volume of brain structures are reduced. Therefore, it is not necessary for a reduction in the size of brain structures to be an index of the numbers of functional neurons.
I would venture to guess that the reduction in the volume of brain structures seen immediately upon the introduction of a AP - as you described - is the result of a reduction in neural activity, as dopamine postsynaptic receptors are blocked. Less neural activity = a reduced need for oxygen, yielding a compensatory reduction of blood flow / tissue volume.
I have no idea what happens after this. Any ideas?
- Scott
Some see things as they are and ask why.
I dream of things that never were and ask why not.The only thing necessary for the triumph of evil is that good men do nothing.
poster:SLS
thread:1121182
URL: http://www.dr-bob.org/babble/20220917/msgs/1121186.html