Long-lasting alterations in behavior and brain neurochemistry following continuous low-level LSD administration

Groups of rats were administered either 80 micrograms LSD-25 continuously over seven days using subcutaneous minipumps, or were given the same total amount of drug in seven daily injections, or were administered vehicle. When tested long after cessation of drug administration, persisting alterations in behavior and brain were found in the continuous LSD groups. In social open-field tests, this consisted of decreased social distance between animals; this effect increased upon repeated testing. In uptake of labeled ligands, this was reflected predominantly by decreased 3H-LSD binding in several limbic regions. LSD appears to have especially persisting neurotoxic effects when administered in a continuous, low-level fashion.