Effect of Intravenous Administration of d‐Lysergic Acid Diethylamide on Subsequent Protein Synthesis in a Cell‐Free System Derived from Brain

Abstract
An initiating cell-free protein synthesis system derived from brain was utilized to demonstrate that the i.v. injection of LSD to rabbits induced a transient inhibition of translation following a brief stimulatory period. Subfractionation of the brain cell-free system into postribosomal supernatant (PRS) and microsome fractions demonstrated that LSD in vivo induced alterations in both of these fractions. In addition to the overall inhibition of translation in the cell-free system, differential effects were noted, i.e., greater than average relative decreases in in vitro labeling of certain brain proteins and relative increases in others. The brain proteins of MW 75,000 and 95,000, which were increased in relative labeling under conditions of LSD-induced hyperthermia, are similar in MW to 2 of the major heat shock proteins reported in tissue culture systems. Injection of LSD to rabbits at 4.degree. C prevented LSD-induced hyperthermia, but behavioral effects of the drug were still apparent. The overall decrease in cell-free translation was still observed, but the differential labeling effects were not. LSD appeared to influence cell-free translation in the brain at 2 dissociable levels: an overall decrease in translation that was observed even in the absence of LSD-induced hyperthermia and differential labeling effects on particular proteins that were dependent on LSD-induced hyperthermia.