Psychophysiological changes during infusions of adrenaline in various doses

Incremental Exercise, Plasma Concentrations of Catecholamines, Reaction Time, and Motor Time during Performance of a Noncompatible Choice Response Time Task

The primary purpose was to examine the effect of incremental exercise on a noncompatible response time task. Participants ( N = 9) undertook a 4-choice noncompatible response time task under 3 conditions, following rest and during exercise at 70% and 100% of their maximum power output. Reaction and movement times were the dependent variables. Maximum power output had been previously established on an incremental test to exhaustion. A repeated-measures multivariate analysis of variance yielded a significant effect of exercise intensity on the task, but observation of the separate univariate repeated-measures analyses of variance showed that only movement time was significantly affected. Post hoc Tukey tests indicated movement time during maximal intensity exercise was significantly faster than in the other two conditions. The secondary purpose of the study was to assess whether increases in plasma concentrations of adrenaline and nor-adrenaline during exercise and power output would act as predictor variables of reaction and movement times during exercise. Catecholamine concentrations were based on venous blood samples taken during the maximum power output test. None of the variables were significant predictors of reaction time. Only power output was a significant predictor of movement time ( R2 = .24). There was little support for the notion that peripheral concentrations of catecholamines directly induce a central nervous system response.

Adrenomedullary function during cognitive testing in attention-deficit/hyperactivity disorder

OBJECTIVE

Reported correlations between epinephrine (EPI) excretion and classroom performance, the cognition-enhancing effects of EPI infusion, increased EPI excretion with stimulants, and reports of decreased EPI excretion in attention-deficit/hyperactivity disorder (ADHD) suggest that sympathoadrenomedullary function might be altered in ADHD. This hypothesis was tested by examining sympathetic and adrenomedullary functioning during cognitive testing in boys with diagnosed ADHD.

METHOD

Urinary excretion of EPI and norepinephrine during a 3-hour cognitive test battery was assessed in 7- to 13-year-old boys. Excretion rates (nanograms per hour per square meter of body surface area) were determined in 200 individuals with ADHD (diagnosed according to DSM-IV criteria), with or without co-occurring oppositional defiant/conduct disorder or learning disorder. A non-ADHD contrast group (n = 51) with similar comorbidity was also studied.

RESULTS

Substantially lower (mean +/- SE) urinary EPI excretion was observed in the ADHD-inattentive subtype (n = 71) compared with the control group (200 +/- 22 versus 278 +/- 24 ng/hr/m2; F = 5.99, p = .015, critical alpha = .017). No diagnostic group differences were seen for norepinephrine excretion. Correlational analysis of both parent- and teacher-rated behaviors revealed that inattention factors consistently negatively predicted urinary EPI excretion.

CONCLUSIONS

The data extend findings of lower adrenomedullary activity during cognitive challenge in individuals with ADHD and suggest that the alteration is associated with inattentive behavior.

Catecholamine response of children in a naturally occurring stressor situation

The present study examined the response of children to a stressor condition. Urine samples were collected from 38 children between ages 10 and 12 preceding a class presentation and again one week later, when no unusual event was occurring. Cognitive tasks and a state anxiety inventory were administered on both occasions. Personality and stressor situation inventories (hypothesized antecedent factors) were completed. Bidirectional changes in catecholamine levels were demonstrated (adrenalin: 55% of the children showed an increase, 29% a decrease; noradrenalin: 47% increase, 40% decrease; 3-methoxy-4-hydroxyphenethylene glycol: 40% increase, 42% decrease). Distinct differences in gender distribution and cognitive performance were demonstrated for the increase and decrease subgroups. It was suggested that both increases and decreases in catecholamine levels represent responses to the stressor situation, with an increase representing an adaptive response and a decrease representing a less adaptive response.

States of anxiety and their induction by drugs

Syndromes of anxiety include generalized anxiety states, various forms of phobic disorder and panic attacks. It is unclear whether panic attacks are a separate syndrome from anxiety states or a more severe form. Drug-induced states of anxiety should provide useful models of the mechanisms of anxiety and its treatment. High-risk populations might be identifiable. Catecholamine infusions produce marked peripheral changes without fully reproducing the central feelings. Lactate infusions also produce anxiety-like states lacking full credibility. Experience with the benzodiazepine-receptor contragonists, the beta-carbolines, is limited but panic states have been reproduced following their use. Caffeine produces an anxiety state in high dose and some panic states have been induced. The critical evaluation of drug-induced anxiety states is a promising way of elucidating the mechanisms, psychological and physiological, associated with clinical anxiety.

The effects of adrenaline injections on human platelet monoamine oxidase and related measures

A double-blind, placebo-controlled, cross-over study in ten normal volunteers assessed the effects of the subcutaneous administration of adrenaline on platelet MAO activity, in an attempt to replicate previous findings of increased MAO activity following adrenaline. Platelet counts, cortisol plasma concentrations, and uptake of metaraminol by the platelets were also determined to elucidate possible mechanisms of action. Blood pressure and heart rate were used as indices of the concentration of adrenaline effectively in circulation. MAO activity towards benzylamine was significantly increased by adrenaline. Non-significant increases were noted in the deamination of tyramine and tryptamine, in platelet counts, cortisol concentrations and metaraminol uptake. Increases in MAO activity were also noted early in the experimental sessions suggesting that other experimental variables such as venepuncture may affect platelet MAO activity. Possible mechanisms for this adrenaline effect are discussed and it is suggested that variables such as "arousal" and "stress" must be taken into account when interpreting clinical data on platelet MAO.

Adrenaline and noradrenaline: relation to performance in a visual vigilance task

Concentrations of adrenaline and noradrenaline in the circulating blood were measured in blood samples taken from subjects as they performed a visual vigilance task or viewed movies, both under identical conditions. For those subjects whose vigilance performance deteriorated it was concluded that the concentration of circulating adrenaline decreases as a function of time in a vigilance task but not under "relaxed" conditions, such as watching motion pictures. crementers under "relaxed"conditions.