The catecholamine, norepinephrine (NE) governs various physiologic processes from vasoconstriction and heart rate to attention and motivation. NE signaling is tightly controlled by a diverse set of macromolecules including biosynthetic enzymes, secretory proteins, ion channels, pre- and post synaptic receptors and NE transporters (NETs). NE signaling is terminated primarily by active reuptake of the catecholamine via cocaine- and amphetamine-sensitive norepinephrine transporters (NETs). Various biologic stimuli are known to regulate NE signaling, and alterations in NE signaling including NE clearance and NET density are observed in cardiovascular diseases and brain disorders. The triggers and molecular mechanisms of transporter regulation are important in the control of extracellular NE concentrations and hence NE signaling. NETs are also expressed in the placenta. This raises the possibility that the established medical complications associated with the maternal use of psychostimulant drugs may arise in part from blocking placental NET. Primary cell cultures offer the facility of in vitro experimentation combined with the verisimilitude of a native cell system to study the molecular mechanisms of transporter regulation a step closer to in vivo animal models. To explore the effect of psychostimulants on NET regulatory pathways, we have developed primary cultures of placental trophoblasts that express endogenous NETs. Using trophoblast cell cultures, we show that NET function and expression are regulated by 1) cocaine treatment, 2) receptor modulation, and 3) kinase(s) activation. Together, these preliminary findings support the proposed experiments to test a specific hypothesis that cocaine regulates NET function and expression via altered cellular mechanisms that result from cocaine effects on NET and/or other cellular targets. The studies proposed in this application will identify the mechanisms of cocaine's action in regulating the function and expression of native NET. Results from these studies will provide valuable scientific insights to our understanding of the role of drugs of abuse in regulating NET function and expression.
