Avoiding common errors in psychedelic researh

D'Oh

In no particular order, here are my recommendations for those of you who do basic science research on psychedelics:

1. Fetal calf serum contains micro-molar concentrations of serotonin (uM)! If you grow cells in culture and use FCS, all the 5-HT receptors are desensitized and down-regulated. We find that commercially available dialyzed serum contains negligible amounts of 5-HT. Typically, we switch the cells to media containing 1% dialyzed FCS for at least 18-24 hrs before study.

2. Neurons in culture do not express 5-HT2A receptors. We find that culturing neurons for at least 18-21 days in vitro (DIV18-21) is required to obtain quantifiable levels of receptor expression and activation.

3. 5-HT2A antagonists are antidepressant in rodents (and humans). If you use a 5-HT2A antagonist to ‘block’ the actions of a psychedelic, the antagonist may have antidepressant drug-like actions which can confound your interpretation of your results.

4. Acute and chronic treatment with both agonists and antagonists down-regulates 5-HT2A receptors in vivo. A few doses of LSD or a single dose of clozapine is sufficient to cause down-regulation in vivo.

5. Ketanserin is a potent VMAT2 inhibitor (has reserpine-like activity). I recommend using M100907 as a better antagonist.

6. Do not use CRO’s for assays. You will end up optimizing weak partial agonists which have no agonist activity in vivo.

7. Br-LSD is the best non-psychedelic 5-HT2A agonist. Avoid lisuride….

8. Psychedelics are profoundly polypharmacologic—any whole animal studies will be confounded by off-target actions of drugs like psilocybin and LSD. I recommend 25-CN-NBOH which is ‘selective enough’. My prediction is that much/most of the imaging and circuitry findings will be confounded by this polypharmacology.