RECEPTOR-RECEPTOR INTERACTIONS AN INTEGRATIVE MECHANISM IN NERVE-CELLS

Several lines of evidence indicate that interactions among transmissio n lines can take place at the level of the cell membrane via interacti ons among macromolecules, integral or associated to the cell membrane, involved in signal recognition and transduction. The present view wil l focus on this last subject, i.e., on the interactions between recept ors for chemical signals at the level of the neuronal membrane (recept or-receptor interaction). By receptor-receptor interaction we mean tha t a neurotransmitter or modulator, by binding to its receptor, modifie s the characteristics of the receptor for another transmitter or modul ator. Four types of interactions among transmission Lines may be consi dered, but mainly intramembrane receptor-receptor interactions have be en dealt with in this article, exemplified by the heteroregulation of D2 receptors via neuropeptide receptors and A2 receptors. The role of receptor-receptor interactions in the integration of signals is discus sed, especially in terms of filtration of incoming signals, of integra tion of coincident signals, and of neuronal plasticity.