Extracellular Dyes Induce Photodegeneration and Photopermeabilization of Vertebrate and Invertebrate Neurones

Abstract

Dyes can sensitize cells to light, resulting in lethal photodynamic damage (review: Spikes, 1989). Although dyes are widely used in neurobiology, their photosensitizing ability has not been investigated thoroughly on the nervous system but was only attested occasionally with electrophysiological techniques (review: Pooler, 1987). In some instances, however, the photodynamic action of dyes has been turned to advantage to produce photoinactivation of single neurones (Miller and Selverston, 1979) or of their neurites (Cohan et al, 1983; Jacob et Miller, 1985). To produce these effects, the dye was injected intracellularly into the neurone with a micropipette, the photoinactivation itself being subsequently achieved by a short pulse of laser light.