Cholinergic Neurons of the Rat Forebrain in Slice Cultures; Interactions with Target Tissue and Effects of Nerve Growth Factor

Abstract

The mammalian forebrain contains two distinct populations of cholinergic neurons. These populations are, first, the cholinergic neurons of the basal forebrain which are located in the medial septum, the diagonal band of Broca and the nucleus basalis of Meynert and which form an ascending and divergent projection to most cerebral cortical and limbic areas, and, second, the cholinergic interneurons of the corpus striatum (Butcher and Woolf, 1986; Mesulam et al., 1978; Wainer et al., 1983). Since their anatomy is well characterized, forebrain cholinergic neurons represent a favorite object for studying mechanisms involved in neuronal growth, targetting and regeneration. We have used the slice culture technique (Gähwiler, 1981,1984a,b) to study the interaction between axons of forebrain cholinergic neurons and their target tissues. Slices of brain tissue cultured with our technique develop into two-dimensional structures which often retain their organotypic morphology. This feature greatly facilitates tracing of fiber growth from one explant to the other. Furthermore, slice cultures can be observed and manipulated during the entire time of growth.