The Journal of Neuroscience, March 1, 2002, 22(5):1698-1708
In Vivo Properties of the Drosophila
inebriated-Encoded Neurotransmitter Transporter
Yanmei
Huang and
Michael
Stern
Department of Biochemistry, Rice University, Houston, Texas
77251-1892
Altering neurotransmitter levels within the nervous system can
cause profound changes in behavior and neuronal function.
Neurotransmitter transporters play important roles in regulating
neurotransmitter levels by performing neurotransmitter reuptake. It was
previously shown that mutations in the Drosophila inebriated
(ine)-encoded neurotransmitter transporter cause increased
neuronal excitability. Here we report a further functional
characterization of Ine. First we show that Ine functions in the
short-term (time scale of minutes to a few hours) to regulate neuronal
excitability. Second, we show that Ine is able to control excitability
from either neurons or glia cells. Third, we show that overexpression
of Ine reduces neuronal excitability. Overexpression phenotypes of
ine include: delayed onset of long-term facilitation and
increased failure rate of transmitter release at the larval
neuromuscular junction, reduced amplitude of larval nerve compound
action potentials, suppression of the leg-shaking behavior of mutants
defective in the Shaker-encoded potassium channel, and
temperature-sensitive paralysis. Each of these overexpression
phenotypes closely resembles those of loss of function mutants in the
para-encoded sodium channel. These data raise the
possibility that Ine negatively regulates neuronal sodium channels, and
thus that the substrate neurotransmitter of Ine positively regulates
sodium channels.
Key words:
neurotransmitter transporter; neuronal excitability; sodium channels; behavioral analysis; overexpression phenotypes; Drosophila
Copyright © 2002 Society for Neuroscience 0270-6474/02/2251698-11$05.00/0