[Abstract Title]. - Society for Neuroscience

242). No significant differences in membrane electrical properties were observed between SPNs
recorded in horizontal vs. transverse slices. When held at -80 mV, in response to intracellular
current injection, most SPNs fired repetitively over a wide range of injected currents. However at
potentials near resting membrane potential (-60 mV; mean Emr -59 mV), there was strong
accommodation and several SPNs fired only single spikes.
We then assessed the modulatory actions of serotonin (5HT), norepinephrine (NE) and dopamine
(DA) on intrinsic membrane properties and glutamate receptor agonist-evoked currents. In the
majority of SPNs recorded from, 5HT and NE depolarized the cell, accompanied by an increase
in membrane input resistance and increased frequency response to current injection. DA alone
and in combination, however, elicited a variety of responses, including hyperpolarizing and
biphasic changes in membrane potential, increased and decreased input resistance, and altered
current-frequency relations. Additionally, individual or combined monoamine application
sometimes unmasked rebound excitation to hyperpolarizing current steps, supporting the
presence of an anomalous rectifier (Miyazaki et al, Brain Research, 1996. 743: 1-10). In voltage
clamp, NMDA and kainate evoked inward currents with characteristics I-V relations. 5HT, NE,
and DA modulated these conductances. 5HT tended to facilitate while DA and NE tended to
depress kainate and NMDA-evoked currents, although a diversity of responses were seen.
Future studies are aimed at further detailing the neuromodulatory properties of specific
monoamine receptor subtypes on SPN ligand- and voltage-gated ion channels.
Disclosures: A.L. Zimmerman, None; S. Hochman, None.
Poster
240. Intrinsic Membrane Properties: Modulation of Neuronal Firing Properties by Inputs
and Activity
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 240.3/E25
Topic: B.10.b. Modulation of neuronal firing properties
Support: NIAAA (R01AA014366) (D.R.)
NIH/NIDA Intramural Research Program (T.S.)
funds provided by the State of California for medical research on alcohol and
substance abuse through the University of California, San Francisco (D.R.)
Title: Rapid actions of glial cell line-derived neurotrophic factor on firing of ventral tegmental
dopaminergic neurons and dopamine release in the nucleus accumbens