The Insect Blood—Brain Barrier

Abstract

Publisher Summary Relatively simple organization of insect central nervous tissues offers some unique advantages for the study of blood-brain barrier phenomena as compared with vertebrate central nervous systems. The concept of the vertebrate blood-brain barrier has been extant since the original observation by Paul Ehrlich, in 1885, that certain aniline dyes stained all the tissues of the body except those of the central nervous system. During the subsequent years this concept has been employed to explain the exclusion of a wide variety of ions and molecules from the central nervous system. In insects, it has been repeatedly shown that changes in the chemical composition of the medium, bathing intact central, and peripheral nervous systems are not reflected in equivalent rapid changes in neuronal function. The postulation of a peripheral diffusion barrier surrounding the central nervous system of insects although providing an explanation for the delayed effects of inorganic ions and pharmacologically-active compounds in intact (as compared with desheathed) preparations also presented some conceptual difficulties. The understanding of the mechanism of insecticidal action and possibly of resistance, require knowledge of the processes involved in the access of poison molecules to synaptic and axonal surfaces. The interpretation of neuronal function in intact central nervous tissues also requires knowledge of the chemical composition of the fluid immediately bathing the neuronal surfaces, for such function is profoundly affected by the composition of the extraneuronal environment.