History of HPPD: Section 2 of 5. Available in PDF
Posted 21 June 2011 - 11:52 AM
Posted 21 June 2011 - 01:23 PM
I find it interesting that non HPPD lsd users do perceive changes, I find it strange how these changes don't bother them.
I also like the suggested cause of the disorder put forth, a tendency for receptor density to not return to normal makes so much sense to me, if I understood everything correctly.
Posted 21 June 2011 - 02:48 PM
Posted 22 June 2011 - 04:02 AM
While changes in receptor density is totally undectable on a standard mri.
Posted 22 June 2011 - 04:11 AM
I have seen an animation showing how a strange molecule that is similar to a neurotransmitter will bind to a receptor as if it were the neurotransmitter, but leaving a kind of damage because of it's different structure. If that is true I wonder why nobody talks about this effect when the subject is HPPD, because looking at the structure of LSD, it is really similar to serotonin.
In time, if the problem is actually a change in receptors density, aren't there lots of methods available to up regulate a group of receptors?
Posted 22 June 2011 - 05:02 AM
2) Regarding the depletion of neurotransmitters: I cover this in my Neurobiology section, but here is the very short version: Depletion can occur via multiple mechanisms. Including agonism at the receptor resulting in depolarization of the cell and release of transmitters in the cell and receptor density lowering immediately. Receptors are replaced and damage to a receptor would persist only if the genes encoding for the receptor were altered, a specific sub-unit of a receptor is improperly coded, or the early immediate-early gene like c-fos. If HPPD individuals were particularly sensitive to returning to normal gene expression after experiencing changes then you have one possible explanation. The neuron is not making receptors at the same rate because of long-term potentiation for example. In the case of benzo use, the GABA receptor will down-regulate. It takes a long time for the cells to process and eventually return to the normal rate to generate the receptor complexes.
3) LSD is great at binding to specific 5-HT receptors. If LSD were to cause a conformational (structural) change in a receptor, it would happen to all users of LSD. Unless, the HPPD individual has a receptor complex that is just enough "off" in structure to be suceptible to this alteration in structure (for example, some chemicals will actually get stuck and block the receptor, I think picrotoxin operates this way. However, the affect would be dose dependent and we would look for problems with other serotonin agonists (including serotonin itself). LSD also is rare in that it has Dopaminergic action as well.
I'll try to get this out as soon as possible. Do know that 5-HT receptor density in blood platelets is one way to measure what is happening in the brain.