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Biomedical subjects

F R Ervin

Publications and source records attributed to F R Ervin.

At least 37 records · Page 2Linked to original sources
PubMed1988

The effect of altered tryptophan levels on mood and behavior in normal human males.

The effect of lowering or raising tryptophan levels was studied in normal males using amino acid mixtures that were tryptophan free or tryptophan supplemented. Tryptophan depletion caused a small but significant alteration in food selection in subjects allowed to select from a buffet. Although carbohydrate and total kilocalories selected were unchanged, significantly less protein was chosen. Tryptophan depletion also caused an acute lowering of mood, suggesting that low serotonin (5-HT) may be involved in the etiology of clinical depression in some patients. No effect of altered tryptophan levels was seen in a laboratory test of aggression. However, a study on vervet monkeys indicated that altered tryptophan levels can influence aggression when the animals are at a high level of arousal. High arousal is known to increase the firing rate of 5-HT neurons. In a preliminary study, tryptophan had a therapeutic effect in aggressive schizophrenic patients. The best effect was seen in impulsive patients, which may have been related to high arousal in these subjects. Although carbohydrate is capable of raising brain tryptophan, not all carbohydrate-induced behaviors are mediated by tryptophan. Thus, sucrose was capable of attenuating alcohol intoxication in normal human males without altering blood alcohol concentrations. However, tryptophan had no effect on ethanol intoxication. The challenge for the future is to define the conditions under which alterations in tryptophan levels can influence brain function.

Affect↗
PubMed1987

A test of possible cognitive and environmental influences on the mood lowering effect of tryptophan depletion in normal males.

In a previous study we found that a tryptophan-deficient amino acid mixture, designed to lower tissue tryptophan and thus brain 5-hydroxytryptamine (5HT) levels, caused a rapid (5 h) lowering of mood in normal males. Because of the importance of this evidence indicating a direct causal connection between low 5HT and low mood, we have now investigated other possible explanations for the mood lowering effect. Research strongly supports the involvement of environmental setting and cognition in the production and experience of emotions. Therefore we investigated how these factors might influence the mood-lowering effects of tryptophan depletion. In an instructional manipulation subjects were either supplied or not supplied with information designed to account for any possible peripheral sensations that might be related to depressive affect. In an environmental manipulation subjects were exposed either to a supportive and comfortable atmosphere (positive environment), or an unrewarding and unstimulating environment (negative environment). In the control group, which received a balanced amino acid mixture, the positive and negative environments had the expected effects on the scores of the Multiple Affect Adjective Checklist, thus indicating the effectiveness of these procedures. In the tryptophan depletion group neither the instructional nor the environmental manipulation had any influence on the mood lowering effect. It may be that tryptophan depletion lowers mood in normal males because low 5HT influences mood directly rather than via cognitive processes. Our data strongly support the idea that 5HT exerts an effect on mood and that low 5HT may, in some patients, be an important factor contributing to the etiology of clinical depression.

Adolescent↗
PubMed1987

The effect of raising or lowering tryptophan levels on aggression in vervet monkeys.

Social groups of vervet monkeys (Cercopithecus aethiops) were given amino acid mixtures that were tryptophan-free (T-), nutritionally balanced (B), or contained excess tryptophan (T+). The T- mixture caused a marked decrease in plasma tryptophan and the T+ mixture a large increase. Behavioral observations were made on the animals after administration of the amino acid mixtures both during spontaneous activity and while the (fasted) animals were competing for food newly placed in the feeder. The only effect of the biochemical manipulations on spontaneous aggression was an increase in aggression of the male animals with the T- mixture. During competition for the food the T- mixture increased and the T+ mixture decreased aggression in the males, while the T+ mixture decreased aggression in females. These data indicate that brain 5-hydroxytryptamine can influence aggression in a primate and suggest that altered tryptophan levels can influence aggression more reliably at higher levels of arousal.

Aggression↗
PubMed1987

Influence of tryptophan availability on selection of alcohol and water by men.

To study the effects of tryptophan on alcohol selection the tryptophan levels in subjects were altered through the administration of amino acid mixtures. Male social drinkers (N = 45) with no psychiatric or medical problems were divided into three groups and consumed a drink that contained, respectively, a nutritionally balanced amino acid mixture, a tryptophan-supplemented mixture, or a tryptophan-free mixture. After a waiting period of 5 hours, blood samples were taken and subjects participated in an ad-lib taste rating of six--one nonalcoholic and five alcoholic--beverages. Water was also made available to subjects. Although there was a marked effect on total and free plasma tryptophan levels showing a dramatic increase in the case of the tryptophan-supplemented group and a decrease in the tryptophan-free group, altered tryptophan levels did not influence the amount of alcohol subjects ingested. Tryptophan supplementation was found to decrease water intake significantly by an unknown mechanism without affecting alcohol selection.

Adolescent↗
PubMed1987

The influence of altered tryptophan availability on ethanol intoxication in normal men.

Because of evidence that altered 5-hydroxytryptamine function may modulate ethanol intoxication, we investigated this in normal social drinkers. Using amino acid mixtures, 5-hydroxytryptamine was influenced by altering levels of its precursor tryptophan. Neither raising nor lowering tryptophan affected alcohol intoxication as measured by a self-report scale and memory and motor tasks. Our data do not support the idea that 5-hydroxytryptamine can modulate alcohol-induced intoxication.

Adolescent↗
PubMed1986

Prediction of alexithymic characteristics from physiological, personality, and subjective measures.

Noting concerns for a comprehensive conceptualization of alexithymic characteristics, the present study examines the potential utility of considering these characteristics as manifestations of deficits in cognitive schemata. Research guided by this conceptualization has identified physiological, subjective, and personality features of alexithymic characteristics. It is reasoned that if this conceptualization has merit, it should be possible to predict the presence of alexithymic characteristics from these features. Results of the present study indicate that a combination of physiological, subjective, and personality variables significantly predicts the presence of alexithymic characteristics as measured by the Schalling-Sifneos Personality Scale. These results are discussed in terms of their implications for a more comprehensive description of alexithymia and the value of the cognitive schema conceptualization.

Adolescent↗
PubMed1986

Cyclic GMP as mediator and biological marker of atrial natriuretic factor.

Both our previous and the present studies established that increases in cyclic guanosine monophosphate (cGMP) reflect the activity of atrial natriuretic factor (ANF). The ANF message is transmitted by particulate guanylate cyclase, which appears to be in intimate contact with the ANF receptor since stimulation of particulate guanylate cyclase is observed even after dispersion of the membranes. The stimulation of smooth muscle and endothelial cells in culture leads to egression of cGMP to extracellular medium where it accumulates for over 2 h. The signal of the extracellular cGMP is magnified and prolonged compared to the intracellular signal. The stimulation of cGMP production by ANF in vascular smooth muscle and endothelial cells appears to be relatively irreversible and the responsiveness is down-regulated by prior exposure to low doses of ANF. Cyclic guanosine monophosphate can also serve as a marker for ANF action. Atrial natriuretic factor fragments of different potencies exert a biological activity that correlates with ANF-induced cGMP increases. In hypertensive rats and monkeys, where acute infusion of ANF leads to an exaggerated diuresis and natriuresis, urinary cGMP does not appear to be different. Overall, cGMP appears to be a mediator and a marker of ANF biological activity and may serve as a useful tool in the study of pathogenesis of hypertension.

Animals↗
PubMed1986

Optic neuritis in cat scratch disease.

A patient with optic neuritis is described whose associated lymphadenopathy, cat exposure, and positive cat scratch antigen skin test suggested the diagnosis of cat scratch disease. Optic neuritis and other neurologic abnormalities, especially encephalopathy, may be associated with, or the presenting manifestation of, cat scratch disease. To our knowledge, this is the fourth case of cat scratch disease-related optic neuritis to be reported.

Adolescent↗
PubMed1985

Tryptophan depletion causes a rapid lowering of mood in normal males.

Normal male human subjects ingested amino acid mixtures which were tryptophan-free, balanced or contained excess tryptophan. The tryptophan-free mixture causes a marked depletion of plasma tryptophan by 5 h. At this time the subjects in the tryptophan-free group had significantly elevated scores on the depression scale of the Multiple Affect Adjective Checklist. The tryptophan-free group also performed worse than the other two groups in a proofreading task carried out while listening to a tape with themes of hopelessness and helplessness (dysphoric distractor). Cognitive theories of depression predict greater distractability of depressed individuals by dysphoric themes. Thus, both measures indicate a rapid mood lowering effect of tryptophan depletion in normal males. This effect is probably mediated by a lowering of brain 5-hydroxytryptamine. Although the mood-lowering effect was not as great as that seen in depressed patients, our results suggest that low brain 5HT might be one factor precipitating depression in some patients.

Adolescent↗
PubMed1984

Spike and wave complexes produced by four hallucinogenic compounds in the cat.

The ability of four hallucinogenic compounds: ketamine, phencyclidine, quipazine and SKF-10,047 to produce spike and wave activity in the limbic system, was studied in cats with permanently implanted electrodes. Electronic frequency integrators were used to analyze the results and the percent of change in electrographic alterations was calculated. All the compounds studied, produced trains of 6/sec spike and waves complexes in the cingulum, rapid synchronous discharges in the amygdaloid complex, and slow wave synchronous activity and spiking in the septal areas. At low but hallucinatory concentrations of these drugs, the cortical EEG was not affected. Exploratory movements directed toward non-existent objects, classified as hallucinatory-like behavior, appeared simultaneous with these changes in the EEG recordings. It was concluded that there could exist a relationship between the appearance of 6/sec spike and wave complexes in the cingulum and the presence of hallucinations, produced by some synthetic drugs in the cat, this activity could be interpreted as the spreading of altered function of limbic and non-limbic nuclei related with this bundle which explain unspecificity of action.

Animals↗
PubMed1984

Cerebrospinal fluid measurements suggest precursor availability and sex are involved in the control of biogenic amine metabolism in a primate.

Biogenic amine precursors and metabolites were measured in cisternal cerebrospinal fluid from 83 female and 55 male vervet monkeys. The results indicate that mean rates of 5-hydroxytryptamine, dopamine, and noradrenaline metabolism in the brain are higher in females than in males. They also suggest that under physiological circumstances tryptophan availability is involved in the control of brain 5-hydroxytryptamine synthesis while tyrosine availability is involved in control of both dopamine and noradrenaline metabolism. The similarities seen between our results on vervets and those seen with human cerebrospinal fluid suggest that the vervet is a useful primate to study.

Animals↗
PubMed1983

Effects of leucine5 - and methionine5 - beta h - endorphin on behavior and electroencephalogram in cats.

Intracerebroventricular administration of leu5 - and met5 - beta h - endorphin produces sequential behavioral changes characterized by restlessness, eye fixation, head tremor, and exaggerated orienting reaction to external auditory stimuli, accompanied by EEG alterations. These changes take place during three stages. Met5- produces an increase in amplitude and reactivity of the theta rhythm in the hippocampus. Leu5- produces a masking of the theta rhythm by the appearance of spiking activity. Leu5- produces a loss of reactivity to visual stimuli not observed with met5-. The exaggerated reaction to auditory stimuli accompanied by an increased response of the reticular formation indicates a sensitivity of some mesencephalic structures (concerned with the modulation of sensory input) to both endorphins. Naloxone blockade of the subcortical (limbic) activity prominent in Stage II reveals the persistence of the first seen Stage I characteristics. These reticular-neocortical effects persist also into Stage III where they are seen intermixed with the limbic effects most prominent in Stage II. This suggests the presence of two endorphin-sensitive neural systems, only one of which is Naloxone reversible, and is that which in the cat covaries with the excited, hyperattentive state rather than the sedation and immobility phase seen in the rat. This dual system is compared to that described by Jacquet (13).

Animals↗