INVESTIGATING DOPAMINE UPTAKE IN MOUSE BRAIN SYNAPTOSOMES VIA CHRONOAMPEROMETRY
Open Access
- Author:
- Ezekian, Brian Donald
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Anne Milasincic Andrews, Ph D, Thesis Supervisor
Dr. Anne Milasincic Andrews, Ph D, Thesis Supervisor
Dr. Lester C Griel Jr., Thesis Honors Advisor - Keywords:
- Dopamine
Serotonin
Serotonin Transporter
Dopamine Transporter
DAT
SERT
5-HT
DA - Abstract:
- Dopamine and serotonin are monoamine neurotransmitters implicated in a suite of physiological functions. Although both serotonin transporters (SERT) and dopamine transporters (DAT) show high affinity for their preferred substrates, recent research has shown that each transporter is not entirely selective, with both allowing some promiscuity of transport (Faraj et al., 1994; Pan et al., 2001; Schmidt and Lovenberg, 1985; Baganz et al., 2008). The serotonin and dopamine neurotransmitter systems have been shown to play overlapping roles in many physiological functions (Murphy et al. 1998; Torres et al., 2003). For example, recent research has shown that drug reward pathways and locomotor behavioral pathways depend on synergy between the serotonin and dopamine neurotransmission systems, as opposed to being solely controlled by the dopamine system, as was once thought. The goal of this thesis research was to gather preliminary data concerning additional interactions between these systems. Homogenized frontal cortex and striatal brain tissue from mice lacking one functional copy of the serotonin transporter gene (SERT +/- mice) was used to investigate dopamine uptake monitored via chronoamperometry. However, dopamine uptake was difficult to characterize, and was observed in only a few of the synaptosomal preparations. In frontal cortex synaptosomes, four preparations were deemed to have successful uptake. The average dopamine uptake rate was 3.6 nmol/g tissue-min after treatment with 1 µM dopamine, with a standard error of 0.6 nmol/g tissue-min. Striatal synaptosomes had a similarly low success rate, with two solutions showing successful uptake. These two preparations were treated with different concentrations of dopamine, so no average rate of uptake was calculated. One synaptosomal solution treated with 1 µM showed an uptake rate of 5.0 nmol/g tissue-min , while the solution treated with 1.5 µM dopamine showed an uptake rate of 1.9 nmol/g tissue-min. In the future, similar dopamine uptake experiments will continue to be performed in brain tissue from SERT +/- mice, as well as with tissue from SERT +/+ and SERT -/- mice. The ultimate goal of this project is to determine the ability of SERT to modify dopamine uptake by either promiscuous uptake of dopamine or by compensatory alterations in DAT expression. Furthermore, this study will also seek to determine whether dopamine that has been cleared from solution is lost from synaptosomes during the process of vacuum filtration.