[Regulation of receptor functions in the CNS]

The basic condition of life is capability to adapt not only to external but also to internal milieu conditions. I.e. receptors are able to change the intensity of signal transduction from the extracellular to the intracellular compartment in a short period. In a specific manner it concerns all receptor structures, both if they are located in cytoplasm or within the membrane. This review concentrates to the mechanisms existing in G protein-coupled receptors. Those protein structures can undergo a homologous or heterologous regulation. Homologous regulation means that only the properties of a receptor system influenced via extracellular signalling are changed. Heterologous regulation means, that receptor properties are changed despite that the extracellular signalling did not influence the receptor. It is possible to consider such changes as one of the level o homeostasis. Both homologous and heterologous regulations are essential for many physiological and pathophysiological processes. The most important examples of these processes, especially in the central nervous system, are reviewed here.