trans

C H A P T E R
15
Neurotransmitters
Richard J. Martin 1 , Jennifer Purcell 2 , Tim Day 1 and Alan P. Robertson 1
1 Department of Biomedical Sciences, College of Veterinary Medicine,
Iowa State University, Ames, IA 50011, USA; and
2 Department of Preclinical Veterinary Sciences, R.(D.)S.V.S., Summerhall,
University of Edinburgh, Edinburgh EH9 IQH, UK
NEUROTRANSMITTERS IN
NEMATODES
Introduction
The study of neurotransmitters in parasitic
nematodes has been encouraged by the need
for the development of novel anti-nematodal
drugs and a requirement for an understanding
of the mode of action of these drugs. The
study of neurotransmitters and the study of
anthelmintics are therefore interconnected.
An early illustration of this connection was
the discovery of the action of the inhibitory
neurotransmitter GABA and the effect of the
anthelmintic piperazine in Ascaris.
We know now that the anthelmintics levamisole,
pyrantel, piperazine and ivermectin
(Figures 15.1, 15.2 and 15.3) mimic the effect
of neurotransmitters that open membrane ion
channels of nematodes (Table 15.1). Piperazine
mimics the effect of the inhibitory transmitter
O
O
CH 3
C
N Acetylcholine
CH 3
CH 3
CH 3
S
S
N
N
N
N
N
CH 3
Levamisole
Pyrantel
FIGURE 15.1 Chemical structures of acetylcholine
and the nicotinic anthelmintics, levamisole and
pyrantel. Note that levamisole is the L-isomer of the
D-L mixture, tetramisole.
Molecular Medical Parasitology
ISBN 0–12–473346–8
359
Copyright © 2003 Elsevier Science Ltd.
All rights of reproduction in any form reserved.