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Query: UMLS:C0023380 (lethargy)
 5,697 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The functions of the central monoamines Norepinephrine (NE) and Serotonin (5HT) can be clarified by the study of behaviors of rats administered selective monoamine toxins. In his home environment the low NE rat has drive deficits and is lethargic, tending to remain in his burrow, but in novel environments this animal acts less frightened than Controls. The low 5HT rat is conversely active and exploratory in familiar environments but frightened in novel environments. These two animals model aspects of depression and anxiety, respectively. 5HT can be thought of as placing the brain into a state of consciousness appropriate for an animal in his nest (i.e., 5HT neurons act as relaxers), and as involved in a type of positive affect related to security, whereas NE neurons are dominant when an animal is vigilant, foraging out in the environment and are involved in a type of positive affect related to goal-directed approach arousal. Monoamine toxins may be produced when the behaviors elicited by these central neuronal systems are negatively reinforced (extinguished).
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PMID:Behavior and the balance between norepinephrine and serotonin. 123 10

Two healthy volunteers were treated with hypoxanthine 3 x 1 g and allopurinol 3 x 100 mg daily for 1 week. During this treatment serum oxypurine concentration and urinary oxypurine excretion increased as expected. No side effects were observed except for some mild daytime drowsiness and lethargy. Measurements of urinary serotonin (5-HT) excretion showed decreases to as much as 60% below initial values. Decreased urinary 5-HT excretion was also found in a patient with incomplete Lesch-Nyhan syndrome during treatment with high doses of hypoxanthine. His neurological symptoms improved slightly. The results suggest that high doses of hypoxanthine exert a nonspecific sedative effect on both patients with Lesch-Nyhan syndrome and healthy controls. The cause is probably a reduced synthesis or release of 5-HT.
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PMID:Reduced urinary serotonin excretion after intake of high doses of hypoxanthine. 270 79

beta-Adrenoreceptor antagonists are liable to produce behavioural side-effects such as drowsiness, fatigue, lethargy, sleep disorders, nightmares, depressive moods, and hallucinations. These undesirable actions indicate that beta-blockers affect not only peripheral autonomic activity but also some central nervous mechanisms. In experimental animals beta-blockers have been found to reduce spontaneous motor activity, to counteract isolation-, lesion-, stimulation- and amphetamine-induced hyperactivity, and to produce slow-wave and paradoxical sleep disturbances. Furthermore, central effects such as tranquilizing influences are used for the treatment of conditions such as anxiety. Several different mechanisms of action could be responsible for these CNS effects: Centrally mediated specific actions on centrally located beta-adrenergic receptors, known to exist downstream from, and at the terminals of, 'vigilance-enhancing' central noradrenergic pathways. Centrally mediated specific actions on centrally located receptors of the non-adrenergic type; an affinity of some beta-blockers towards 5-HT-receptors is well documented. Centrally mediated non-specific actions on centrally located neurones, owing to the membrane-stabilizing effects of beta-blockers. Peripherally mediated actions whereby beta-blockers induce changes in the autonomic activity in the periphery, which are relayed to the CNS to induce changes in activity of a variety of central systems. It can be assumed that with any one of the beta-blockers all these mechanisms come into play, yet with varying degrees depending on characteristics of the drugs such as lipophilicity and hydrophilicity, the ratio of antagonist versus (partial) agonist properties, affinity to 'alien' receptor sites, strength of membrane-stabilizing activity, stereospecific affinity, and potency.
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PMID:CNS-related (side-)effects of beta-blockers with special reference to mechanisms of action. 286 51

Four experiments were conducted to determine the effect of parachlorophenylalanine (PCPA) on the male mating behavior of a line of chickens genetically selected for low mating frequency and to determine the effect on brain concentrations of 5-hydroxytryptamine, dopamine (DA) and norepinephrine (NE). Mating behavior was not affected by moderate levels (less than 64 mg/kg) of PCPA, and decreased significantly when higher levels (100 mg/kg) of the drugs were administered. Results suggest that elevated brain serotonin titers were not causing the low mating frequency associated with the selected line. Birds receiving higher levels of PCPA exhibited a lethargy which persisted for approximately ten days after withdrawal of the drug. Serotonin, DA, and NE were all significantly reduced in the brains of birds receiving PCPA (30 mg/kg).
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PMID:Mating behavior and brain biogenic amine concentrations in chickens treated with parachlorophenylalanine (PCPA). 614 60

MDMA (3,4-methylenedioxymethamphetamine) or 'Ecstasy' was scheduled as an illegal drug in 1986, but since then its recreational use has increased dramatically. This review covers 15 years of research into patterns of use, its acute psychological and physiological effects, and the long-term consequences of repeated use. MDMA is an indirect monoaminergic agonist, stimulating the release and inhibiting the reuptake of serotonin (5-HT) and, to a lesser extent, other neurotransmitters. Single doses of MDMA have been administered to human volunteers in double-blind placebo-controlled trials, although most findings are based upon recreational MDMA users. The 'massive' boost in neurotransmitter activity can generate intense feelings of elation and pleasure, also hyperactivity and hyperthermia. This psychophysiological arousal may be exacerbated by high ambient temperatures, overcrowding, prolonged dancing and other stimulant drugs. Occasionally the 'serotonin syndrome' reactions may prove fatal. In the days after Ecstasy use, around 80% of users report rebound depression and lethargy, due probably to monoaminergic depletion. Dosage escalation and chronic pharmacodynamic tolerance typically occur in regular users. Repeated doses of MDMA cause serotonergic neurotoxicity in laboratory animals, and there is extensive evidence for long-term neuropsychopharmacological damage in humans. Abstinent regular Ecstasy users often display reduced levels of 5-HT, 5-HIAA, tryptophan hydroxylase and serotonin transporter density; functional deficits in learning/memory, higher cognitive processing, sleep, appetite and psychiatric well-being, and, most paradoxically, 'loss of sexual interest/pleasure'. These psychobiological deficits are greatest in heavy Ecstasy users and may reflect serotonergic axonal loss in the higher brain regions, especially the frontal lobes, temporal lobes and hippocampus. These problems seem to remain long after the recreational use of Ecstasy has ceased, suggesting that the neuropharmacological damage may be permament. Copyright 2001 John Wiley & Sons, Ltd.
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PMID:Human psychopharmacology of Ecstasy (MDMA): a review of 15 years of empirical research. 1240 36

Interferon-alpha (IFN) is widely used for the treatment of viral illnesses and other chronic diseases, though its usefulness is hampered by a problematic side-effect profile. In particular, IFN-alpha induces neuropsychiatric and neurotoxic side effects, including depression, anxiety, insomnia, lethargy, confusion, and psychosis. Of particular interest, a number of patients develop full psychiatric syndromes, particularly depressive disorders. Recent evidence suggests that conventional antidepressants (especially selective serotonin reuptake inhibitors) are effective in preventing or reducing IFN-induced side-effects, but even these compounds are not 100% effective in preventing these symptoms. As such, alternative treatments must be considered. Non-steroidal anti-inflammatory drugs (NSAIDs) are known to counteract a number of IFN-induced side effects, including cytokine activation, stress hormone release, and neurochemical alterations (reduced 5-HT [serotonin]). NSAIDs are widely recommended for various aspects of flu-like symptoms or sickness behaviors in humans, including those induced specifically by IFN. In addition, NSAIDs appear to be effective in treating premenstrual dysphoric disorder. These data indirectly specify a role for NSAIDs in syndromes with a prominent depression component. Drawing from an extensive pre-clinical and clinical research base, we hypothesize that pretreatment with NSAIDs will not only reduce the incidence of flu-like symptoms, but also prove effective for the prevention or reduction of IFN-induced depression.
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PMID:IFN-induced depression: a role for NSAIDs. 1460 39

A newborn of a SSRI-treated mother presented with lethargy, no crying, and no response to tactile stimulation. EEG findings were abnormal. Laboratory and clinical evaluations were normal. He recovered at the age of two weeks. Serotonin is a neurotransmitter that has an important roll in pain modulation during fetal neurodevelopment. We suspect these symptoms are attributed to the intrauterine exposure to paroxetine, through modulation of pain signals.
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PMID:Paroxetine use throughout pregnancy: does it pose any risk to the neonate? 1508 45

The original central fatigue hypothesis suggested that an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its well known effects on sleep, lethargy and drowsiness and loss of motivation. Several nutritional and pharmacological studies have attempted to manipulate central serotonergic activity during exercise, but this work has yet to provide robust evidence for a significant role of serotonin in the fatigue process. However, it is important to note that brain function is not determined by a single neurotransmitter system and the interaction between brain serotonin and dopamine during prolonged exercise has also been explored as having a regulative role in the development of fatigue. This revised central fatigue hypothesis suggests that an increase in central ratio of serotonin to dopamine is associated with feelings of tiredness and lethargy, accelerating the onset of fatigue, whereas a low ratio favours improved performance through the maintenance of motivation and arousal. Convincing evidence for a role of dopamine in the development of fatigue comes from work investigating the physiological responses to amphetamine use, but other strategies to manipulate central catecholamines have yet to influence exercise capacity during exercise in temperate conditions. Recent findings have, however, provided support for a significant role of dopamine and noradrenaline (norepinephrine) in performance during exercise in the heat. As serotonergic and catecholaminergic projections innervate areas of the hypothalamus, the thermoregulatory centre, a change in the activity of these neurons may be expected to contribute to the control of body temperature whilst at rest and during exercise. Fatigue during prolonged exercise clearly is influenced by a complex interaction between peripheral and central factors.
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PMID:Central fatigue: the serotonin hypothesis and beyond. 1700 50

Mirtazapine (Remeron) is a newly approved medication for the treatment of depression. It is an alpha(2)-adrenergic antagonist that causes increased levels of neuronal norepinephrine and serotonin. It is also believed to be an antagonist at the serotonin receptors 5-HT(2) and 5-HT(3). Little is known about isolated mirtazapine ingestions. We conducted a retrospective chart review of mirtazapine ingestions reported to our Poison Center during 2004. A standardized data sheet was completed collecting information regarding standard demographic data along with co-ingestants, neurologic and cardiovascular symptoms, and disposition. Data collection was reviewed by a second investigator, and a kappa score was calculated. Of 71 patients identified with mirtazapine ingestions, there were 33 isolated exposures that were further reviewed. A kappa score for inter-reviewer reliability was calculated and at 0.61, 95% confidence interval 56-70. The average age of these patients was 27 years (range 6-82 years), with the mean ingestion of 343 mg (range 15-1500 mg). The most common neurologic symptom was drowsiness seen in 8/23 patients, 1 patient became agitated, and 14 patients had no abnormal neurologic findings. Cardiovascular effects were recorded in 4/23 patients, with 3 patients exhibiting tachycardia and 1 patient with bradycardia and hypotension. Seven of 23 patients required admission; there were no deaths. Mirtazapine overdoses are generally very well tolerated, with the most common symptoms being drowsiness and lethargy. This study is limited by being a retrospective chart review.
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PMID:Outcomes after isolated mirtazapine (Remeron) supratherapeutic ingestions. 1797 74

It is clear that the cause of fatigue is complex, influenced by both events occurring in the periphery and the central nervous system (CNS). It has been suggested that exercise-induced changes in serotonin (5-HT), dopamine (DA), and noradrenaline (NA) concentrations contribute to the onset of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its documented role in sleep, feelings of lethargy and drowsiness, and loss of motivation, whereas increased DA and NA neurotransmission favors feelings of motivation, arousal, and reward. 5-HT has been shown to increase during acute exercise in running rats and to remain high at the point of fatigue. DA release is also elevated during exercise but appears to fall at exhaustion, a response that may be important in the fatigue process. The rates of 5-HT and DA/NA synthesis largely depend on the peripheral availability of the amino acids tryptophan (TRP) and tyrosine (TYR), with increased brain delivery increasing serotonergic and DA/NA activity, respectively. TRP, TYR, and the branched-chained amino acids (BCAAs) use the same transporter to pass through the blood-brain barrier, meaning that the plasma concentration ratio of these amino acids is thought to be a very important marker of neurotransmitter synthesis. Pharmacological manipulation of these neurotransmitter systems has provided support for an important role of the CNS in the development of fatigue. Work conducted over the last 20 y has focused on the possibility that manipulation of neurotransmitter precursors may delay the onset of fatigue. Although there is evidence that BCAA (to limit 5-HT synthesis) and TYR (to elevate brain DA/NA) ingestion can influence perceived exertion and some measures of mental performance, the results of several apparently well-controlled laboratory studies have yet to demonstrate a clear positive effect on exercise capacity or performance. There is good evidence that brain neurotransmitters can play a role in the development of fatigue during prolonged exercise, but nutritional manipulation of these systems through the provision of amino acids has proven largely unsuccessful.
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PMID:Amino acids and the brain: do they play a role in "central fatigue"? 1857 73


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