Monoamine Oxidase: A Cross Species Examination
Abstract
Monoamine oxidase (MAO) is presently being examined
at the National Institute of Mental Health by Dr. Dennis
Murphy and his associates. MAO is an enzyme thought to
be related to certain psychological disorders which are
studied both in the wards and laboratories of NIMH.
MAO is found inside the nerve ending. It degrades
(deaminates) neuotransmitters, thereby regulates transmitter concentration. Neurotransmitters are small
molecules that are synthesized in the neurons and
released from the nerve endings into the synaptic site.
At the post synaptic site transmitters interact with
the receptors which activate the effector cells.
The purpose of the research there has been to
clarify the role of neurotransmitters. especially as they
relate to manic-depression and schizophrenia, and to
determine the mechanisms by which anti-depressive drugs
effect the neurotransmitters. Though these mechanisms
are generally understood, more research is·needed to
clarify other mechanisms concerning an effective drug
treatment and the genetic contributions to these disorders.
Patients respond differently to different drugs. The
cause of this is probably both biological and behavioral
and so the specific effect of drugs must be more accurately
assessed. Patients must be divided into subgroups so
that more predictable responses to drugs can be realized. If manic-depressive patients are biologically different
from normal patients then there may be a genetic cause
and the mode of the genetic .transmission needs to be
explored.
This study makes no attempt to directly answer the
above questions. Rather its purpose is to aid in the
characterization of MAO. Obviously, it is not possible
to relate MAO to psychological disorders in animals
other than man (with the possible exception of some
primates); but it is possible to further characterize
the enzyme using animals and thereby provide basic
information which may be useful in studying psychological
disorders.
This project, sparked by a possible evolutionary
trend noticed in primate groups, is a cross-species
examination done to discover if MAO is present. in the
platelets and plasma of other species. If it was
found, then.to further determine the level of MAO activity
and which form of the enzyme is present.