Membranous neuronal and neuroglial inclusions produced by intracerebral injection of Suramin.

A single intracerebral injection of 5 micrometer of the trypanocidal drug Suramin, into the left hemisphere of young rats, resulted in the formation of membranous inclusion bodies within the perikarya and processes of neurones and neuroglia. These inclusion bodies were round or oval in shape and 0.5-3.0 micrometer in their longest diameter. They were bounded by a single trilaminar membrane and contained closely packed membranes in concentric, curved or parallel arrays. The inclusions were distributed throughout the cerebral cortex and underlying hippocampus at the injection site, and in reduced numbers up to 1 mm anteriorly and posteriorly from it. They formed within 22 hr of the injection and had increased in numbers and in the complexity of their arrays 3 days after injection. Within 14 days, the inclusions were markedly reduced in number. As Suramin is known to inhibit lysosomal hydrolases required for the degradation of proteins, glycolipids and mucopolysaccharides, the membranous inclusions could form as a result of the accumulation of these substances within lysosomes. These experiments indicate a possible experimental model for storage diseases. It is hoped that the extension of this paradigm to other enzyme inhibitors will provide a new means of identifying some of the unusual inclusions that can be found in neurones and neuroglia (Rees 1975).