Central Glucocorticoid Receptor Immunoreactive Neurons: New Insights into the Endocrine Regulation of the Brain

The present work has demonstrated that in the brain glucocortocoids represent an important wide-spread signal in volume transmission, underlining the role of stress responses in controlling brain function. The role of glia cells in VT may be to control the extracellular fluid ion composition and the shaping of the extracellular fluid pathways for signal diffusion. They also control the release, uptake and metabolism of endocrine and paracrine signals and contain receptors for such signals. The role of the neurons in VT is to represent the location of sources and sinks for electrotonic signals and the sites of release of paracrine signals and recognition of endocrine and paracrine signals. As seen in Table 2, the VT is characterized by a low-speed and a long-term action, a high degree of divergence and plasticity and a low safety of the transmission process. Instead, WT is the classical type of transmission which is neurons linked and operates with a high speed and safety, short-term actions and a low divergency and plasticity. By the existence of VT the integrative capability of the central and peripheral nervous system is increased. Thus, VT is subjected to only weak neuroanatomical constraints and it probably affects the computing characteristics of the neuronal networks. It should be considered that the chemical transmission lines in a liquid volume are practically infinite and not expensive in biological terms. No computation is required; instead only a biological trap is needed, that is, the receptors, recognizing and transducing the signals in volume transmission.