[Abstract Title]. - Society for Neuroscience

Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 284.6/QQ1
Topic: E.07.b. Integration of peripheral signals: Systems
Support: NIH Grant F010384
NIH Grant F007995
Title: High temporal resolution monitoring of leptin-modulated dopamine release by
microdialysis coupled to MEKC
Authors: *M. L. PERRY, M. SHOU, G. M. LEINNINGER, M. G. MYERS, Jr., R. T.
KENNEDY;
Univ. of Michigan, Ann Arbor, MI
Abstract: Conventionally, microdialysis has been coupled to HPLC for off-line detection of in
vivo-sampled analytes of interest. The dialysate must be analyzed in 10-30 minute fractions to
meet the concentration detection limits for these assays. The low temporal resolution of analysis
by HPLC prevents observation of rapid changes in extracellular neurotransmitter concentrations.
Micellar electrokinetic chromatography (MEKC), a variant of capillary electrophoresis, requires
smaller sample volumes and permits higher sampling frequency. A MEKC-based separation has
been developed that resolves naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized dopamine in
90. The high mass sensitivity of MEKC and the fast separation time facilitate on-line monitoring
of rapid in vivo dopamine release. We applied this near real-time monitoring technique to the
study of leptin-modulated dopamine release in the nucleus accumbens (NAc). Leptin-receptor
expressing neurons in the lateral hypothalamus (LHA) project to the ventral tegmental area
(VTA), and intra-LHA leptin infusion of leptin in ob/ob mice increased tyrosine hydroxylase
expression in the VTA and tissue DA content in the NAc. This work aimed to determine whether
leptin modulates DA release in the NAc of Sprague-Dawley rats by either causing an increase in
basal extracellular dopamine concentration or by increasing amphetamine-stimulated dopamine
release. Rats received either 1 mg/kg leptin or vehicle i.p. followed several hours later by 1
mg/kg amphetamine s.c. Leptin had no effect on dopamine release under basal conditions but
increased the amphetamine-stimulated release as compared to vehicle. These results suggest the
importance of the LHA to VTA pathway in the regulation of striatal DA homeostasis in response
in normal animals.
Disclosures: M.L. Perry, None; M. Shou, None; G.M. Leinninger, None; M.G. Myers,
None; R.T. Kennedy, None.
Poster