On the Intracellular Transmitter Reception.

The idea on the possibility of intracellular neurotransmitter receptor localization exists already more than half a century, however it remains disputable until now. The data on such neurotransmitter receptors' localization in unicellular organisms, early (pre-nervous) embryos and in adult cells, including neurons are summarized in the present paper. These data were obtained both using pharmacological experiments with pairs of hydrophilic and lipophilic analogues of transmitter receptor ligands, by direct ligand microinjection into the cells, and also as by labelled ligand binding and using electrophysiological methods. The data on the intracellular localization of transmitter receptors provokes to critically evaluate the current understanding of the origin of transmitter substances and corresponding receptors. It is suggested that they were formed as the result of the evolution of function of systems that originally were coupled to the processes of intracellular syntheses but not to cellular interactions. [ABSTRACT FROM AUTHOR]