Effects of Neurohormones on Glial Cells

Abstract

This chapter focusses on the effects of neurohormones on glial cells. The receptors for several putative neurohormones are expressed by transformed glial cells and by immature glial cells from rodent brain. The two most enigmatic fields of neuroscience, namely, the glial function and the problem of learning and memory, have been combined in the speculation that interactions between neurons and glial cells may be the basis of the higher adaptive functions of the brain. The glial cells and neurons not only exchange trophic or mitotic factors but also integrate their information-processing capacity by the exchange of hormonal signals. Both anatomical and physiological evidence suggests that, in addition to their role as neurotransmitters, biogenic amines might also act as neuromodulators or neurohormones, a mode of operation intermediate between the private addressing of classical synaptic messengers and the broadcasting of neuroendocrine secretion. The problem of obtaining mature glial cells of sufficient purity and integrity from adult brain is still unsolved. Most studies are performed using cultured glial cells, either permanent cell lines derived from tumors or primary cultures from perinatal rodent brain enriched in glia-like cells. The chapter briefly discusses the question of the reliability of these cells as models for neuroglia.