Journal of Neuroscience, Vol 15, 1025-1034, Copyright © 1995 by Society for Neuroscience
Characterization of K+ currents and the cAMP-dependent modulation in cultured Drosophila mushroom body neurons identified by lacZ expression
NJ Wright and Y Zhong
Cold Spring Harbor Laboratory, Center for Learning and Memory, New York 11724.
Electrophysiological analysis of cultured neurons provides a potential
approach toward understanding the physiological defects that may contribute
to abnormal behavior exhibited by mutants of the fruit fly Drosophila.
However, its application has been restricted by an inability to identify a
particular functional or anatomical subpopulation of neurons from the CNS.
To study neurons composing the CNS mushroom body proposed as a center for
insect olfactory learning, we utilized a Drosophila enhancer detector line
that expresses a lacZ reporter gene in these neurons and identified them in
acutely dissociated larval CNS cultures by vital fluorescent staining. The
patch-clamp analysis suggests that whole-cell voltage-activated K+ currents
can be classified into two types in identified mushroom body neurons. Type
1 current comprises a TEA-sensitive slowly inactivating current and
noninactivating component while type 2 current contains a 4- AP-sensitive
transient A-current and a noninactivating component. Application of cAMP
analogs induced distinct modulation of type 1 and type 2 currents. Our
results demonstrate that the expression of the lacZ gene and the subsequent
staining do not significantly alter the different types of K+ currents.
This initial characterization provides a basis for further analysis of
mutations that impair learning and memory resulting from an abnormal cAMP
cascade preferentially expressed in the mushroom body.