Lysergic Acid Diethylamide (LSD-25) Antagonists
A M A Archives of Neurology & Psychiatry – February 01, 1958
Source: OpenAlex
Summary
A compound similar to Lysergic acid diethylamide (LSD-25), known as 1-methyl-d-lysergic acid diethylamide (MLD-41), shows intriguing effects on both Siamese fighting fish and humans. In experiments, MLD-41 was found to be roughly 10% as effective in fish compared to LSD-25, while in humans, it exhibited about 33% effectiveness. These findings suggest that prior administration of MLD-41 may develop tolerance to LSD-25, highlighting complex interactions between pharmacology and behavior in both species. The sample sizes for these observations included various test subjects across both groups.
Abstract
A. Introduction It has been shown1,2that 2 mg. of crude beef brain extract per milliliter of water blocks the usual effect of 2μg of LSD-25 per milliliter in the outside liquid on the Siamese fighting fish.* The experiments to be reported here are the study of a blocking effect probably produced by another mechanism: the development of tolerance3to LSD-25 in man by the prior administration for a period of days of a compound similar to LSD-25. This compound, 1-methyl-d-lysergic acid diethylamide (MLD-41), produces in man reactions indistinguishable from LSD-25 but has a higher reaction threshold. It will be shown on the basis of our data that MLD-41 affects both the Siamese fighting fish and man in a manner similar to LSD-25. However, there are important differences; in the fish it is about 1/10 as effective as LSD-25, whereas it is approximately 1/3 as effective in man.