Neurotransmitter transporters: Target for endocrine regulation

Aminergic signaling in the CNS is terminated by clearance from the synapse via high-affinity transporter molecules in the presynaptic membrane. Relati vely recent sequence identification of these molecules has now permitted th e initiation of studies of regulation of transporter function at the cellul ar and systems levels. In vitro studies provide evidence that the transport ers for dopamine, serotonin, and gamma-aminobutyric acid are substrates for regulation by protein kinase C signaling. In vivo studies provide evidence that insulin and adrenal and gonadal steroid hormones may regulate the syn thesis and activity of the transporters. Future directions should permit ev aluation of the role of endocrine regulation in neurotransmitter clearance, and thus in the maintenance of normal CNS aminergic signaling.