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.