Microdialysis Coupled with Electrochemical Detection - Drugs of Abuse: Neurological Reviews and Protocols - page 404

taking into account both the costs and time required, or to learn quickly some
useful insights that otherwise may require years of experience to gain. The
last part of this chapter is devoted to prevention of some of the most common
problems that may be encountered in microdialysis laboratories, limiting
the discussion to points that are not discussed or only briefl y mentioned in
technical manuals.
The information regarding equipment should not be used as a “simple to
read” substitute for operating manuals. Careful reading of operating manuals
indeed has to be considered essential for understating the true role of each
piece of equipment and to manage microdialysis and ED. Nevertheless it is
recognized that they are often not very helpful to solve problems quickly when
one is in trouble. Often in this case, a colleague with good experience may be
more helpful even than the manufacturer's technical assistance. Moreover this
chapter could allow a researcher entering the fi eld to predict advantages and
problems that can be encountered with ED, so that the decision whether to buy
a microdialysis system can be better evaluated. Part of this chapter is dedicated
to optimization of the system to increase productivity.
1.2. Fields of Application of ED
DA, NA, and 5-HT represent three major neurotransmitters in the mam-
malian central nervous system (CNS). Their wide distribution in brain, their
involvement in CNS pathologies such as psychosis and depression, the relevant
role they play in the effects of drugs of abuse, and in behavior in general,
has promoted an endless series of research that has provided an enormous
contribution to knowledge of CNS function. This extraordinary success is
mainly the result of the relative ease of measuring these three neurotransmitters
and their metabolites in biological fl uids, extracts, and tissues (2) . The ease
of estimating DA, NA, and 5-HT is due mainly to their chemical structure,
whereas the growing facility with which their role in the brain has been
ascertained is due to their unique function as neurotransmitters, in contrast to
other neurotransmitters such as GABA or glutamate whose detection in vivo
has been hampered by their presence in brain fl uids with a function other than
neurotransmission (3) .
The possibility of detecting DA, NE, and 5-HT by ED in extracts such as
dialysate from freely moving animals has given an extraordinary advantage to
researchers. No comparison can be made with old techniques in which a time
course of a drug effect on a specifi c neurotransmitter could be made only by
scarifying groups of animals at given time and assessing the total amount of
a transmitter, without being able to distinguish the fraction that is actively
released upon depolarization. The possibility of detecting an increasing
number of neurotransmitters, by implanting concentric microdialysis probes