Physiology of glia: Glial-neuronal interactions

This chapter provides an overview of the physiology of neuroglia. The glialneuronal relationship begins during the embryonic development of the organism and continues throughout its life. Pertinent aspects of glial pathophysiology and its consequences for neural function and dysfunction are discussed in the chapter for understanding the normal physiology. The blood-brain barrier appears to be more a function of vascular endothelial cells than glial cells. The chapter focuses on the functional glial-neuronal interactions and suggests that glia are active, rather than passive partners, in the ongoing glial-neuronal relationship and are critical for sustained and efficient neuronal functioning. Neurons and glial cells may interact by a reciprocal influencing of differentiation. The level of potassium in the extracellular space surrounding the neuron appears to be regulated by glia. The membrane potential of glia is primarily dependent on the extracellular and intracellular distribution of potassium. Glial cells contribute to neuronal functioning by extraneuronal regulation of neurotransmitters in the CNS and, possibly, more directly, as in the glutamate-glutamine cycle.