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Biomedical subjects

D L Murphy

Publications and source records attributed to D L Murphy.

At least 451 records · Page 25Linked to original sources
PubMed1980

Presynaptic noradrenergic regulation during depression and antidepressant drug treatment.

A specific testable hypothesis in which supersensitive alpha-2-adrenoreceptors play an important role in the etiology and maintenance of affective illness is presented based on the following observations: (1) published findings of changes in adrenergic receptors in the periphery and brains of rats in response to antidepressant regimens; (2) new studies of the monoamine oxidase type A-inhibiting antidepressant clorgyline, specifically relating to adaptation in the alpha-adrenergic presynaptic negative feedback system; (3) human peripheral alpha-adrenergic receptor changes from studies of patients with affective illness; and (4) observations from animals and humans experiencing stress and withdrawal from chronic amphetamine and opiate administration, suggesting that the development of supersensitive alpha-2-adrenoreceptors may lead to affective illness in vulnerable individuals. Old and new pharmacologic treatments are then discussed in terms of their capacity to specifically alter adrenergic receptor state.

Animals↗
PubMed1980

An 18-month followup of students biologically at risk for psychiatric problems.

A prospective investigation using platelet monoamine oxidase activity and cortical evoked response augmenting/reducing to predict the onset of new episodes of affective disorders was conducted in a college sample. During an 18-month period between clinical interviews, higher incidences of major depression and hypomania characterized the low MAO/aociated with affective psychopathology in the original retrospective study.

Bipolar Disorder↗
PubMed1980

Parents of high risk subjects defined by levels of monoamine oxidase activity.

Thirty-seven parents of probands with low platelet monoamine oxidase (MAO) activity levels and 38 parents of high MAO probands were examined for MAO activity, past and present psychopathology, and reported psychopathology in other relatives. Results showed generally positive and significant correlations between parents' and children's MAO levels, significantly greater rates of "high MAO related" disorders in parents and relatives of high MAO probands and of "low MAO related" disorders and symptoms in parents and relatives of low MAO probands. Support for a two-directional monoamine hypothesis of affective disorders is suggested.

Alcoholism↗
PubMed1980

Biological and behavioral consequences of alterations in monoamine oxidase activity.

Monoamine oxidase (MAO) has many intraneuronal regulatory metabolic functions as well as detoxifying properties. Inhibition of the enzyme leads to rapid changes in the cellular concentrations of neurotransmitter amines and in the balance between different amines in neurons. Longer term alterations in MAO activity are accompanied by secondary, adaptational changes in neurotransmitter-related receptors, other enzymes, and additional cell functions in brain and other tissues. In addition, MAO inhibition is accompanied by marked changes in the sensitivity of the organism to some dietary constituents (e.g., tyramine, tryptophan, and other amines and amine precursors) as well as to many drugs (e.g., sympathomimetics, opiates, reserpine, and caffeine). While nearly complete MAO inhibition has been said to be required for direct behavioral changes to occur, partial MAO inhibition (reductions of 25-75 percent in enzyme activity) or selective inhibition of either the MAO-A or MAO-B form of the enzyme-especially after longer term inhibitor administration-lead to readily demonstrable alterations in the sensitivity of both animals and man to a variety of exogenous agents, and are also associated with a number of biological changes, including those involving neuroendocrine, blood pressure, and sleep mechanisms. These changes in cellular mechanisms and physiological functions may provide models for evaluating the significance of moderate (40 percent) mean reductions in platelet MAO activity found in chronic schizophrenic patients and some other psychiatric patient populations. The basic principle underlying these models is that MAO inhibition leads to impaired regulation in many neurotransmitter systems and other cellular functions, yielding consquent deficits in the attenuation of responses to exogenous stimuli and to endogenous psychobiological changes.

Animals↗
PubMed1980

Schizophrenia and platelet monoamine oxidase: research strategies.

The most widely replicated neurochemical finding in schizophrenia is that of lower levels of monoamine oxidase (MAO) in the platelets of chronic schizophrenics than in normal controls. Yet, the etiological role of MAO in schizophrenia remains to be demonstrated. The incidence of low MAO in other psychiatric disorders, effects of diet, hormones and drugs, and relationships of platelet MAO to brain levels and genetic mechanisms remain unclear. This article examines factors which make any biological indicator suitable for use as a diagnostic test for schizophrenia and inquires into the methodological pitfalls and unexamined assumptions of various research strategies which use this measure.

Age Factors↗
PubMed1980

Platelet monoamine oxidase activity and clomipramine-induced mania in unipolar depressed patients.

During an asymptomatic phase platelet MAO activity was examined in 28 unipolar patients, 8 of whom previously had developed mania during clomipramine treatment for depression. The platelet MAO activity was not lower in these switchers than in 20 unipolar patients who did not become manic during a similar clomipramine treatment. High but nonsignificant correlations were found among platelet MAO activity and age of onset of mania, duration of clomipramine treatment before the switch, and the duration of manic behavior. These clinical variables correlated significantly amongst themselves. The high and normal platelet MAO activities of these patients neither support nor rule out a Bipolar I diagnosis. This study supports the pharmacologic basic of the induction of mania during clomipramine treatment.

Adult↗
PubMed1979

A correlation between platelet monoamine oxidase activity and plasma prolactin concentrations in man.

Increases in plasma prolactin concentrations produced by alpha-methyl-p-tyrosine, a catecholamine synthesis inhibitor, varied inversely with baseline platelet monoamine oxidase activity in 12 patients with chronic schizophrenia. In normal volunteers with low monoamine oxidase activity and in unmedicated patients with chronic schizophrenia, plasma prolactin concentrations varied directly with platelet monoamine oxidase activity. No such relationship was found in normal subjects with high platelet monoamine oxidase activity. These data suggest that platelet monoamine oxidase activity reflects monoaminergic activity in the tubero-infundibular system, which in turn affects plasma prolactin concentrations. This relationship may be important in patients with low platelet monoamine oxidase activity, such as some chronic schizophrenics.

Blood Platelets↗