Writing sample—Stephen X. Arthur—neuroscience review #4 Page 1 Mechanisms of homologous neurotransmitter receptor desensitization in the central nervous system

Desensitization of neurotransmitter receptors is a reduced response to repeated agonist stimulation over time-courses ranging from msec to days, depending on the system. It has implications for neuronal homeostasis, information processing, tonic inhibition, synaptic plasticity, and epigenesis. In homologous desensitiza-tion the cell is desensitized to only one agonist, whereas in heterologous desensi-tization there is a diminished response to other agonists as well. Desensitization can also be modulated, that is, the rate of desensitization by one agonist can be changed by the actions of another receptor agonist or second messenger. By necessity this paper will focus on mechanisms of homologous desensitization only, with occational reference to heterologous desensitization and modulation where warranted. Myriad examples of receptor desensitization have been found outside the CNS (Hollenberg, 1985a), such as with hormones, growth factors, and autonomic neurotransmission. Many mechanisms have been proposed, both homologous and heterologous, including receptor phosphorylation, disulphide-sulfhydral ex