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Query: UMLS:C0002622 (amnesia)
 5,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparison was made of free aminoacids content in the brain of rats after amnesia induced by an electric shock or an injection of iproniazid. Immediately after the electric shock the cystine content rises and there is a drop in the content of aspartic acid, proline and isoleucine. Twenty four hours later the content of most of the amino acids rises. A correlation has been found between the glycine content in the brain and the degree of amnesia. Under the influence of iproniazid the content of aspartic and glutamic acids, alanine, tyrosine and phenylalanine in the brain drops and that of proline, glycine, cystine and valine rises. It is assumed that the differences between the content of free aminoacids in the brain after electric shock and iproniazid reflect those between the mechanisms of amnestic action of the two agents.
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PMID:[Change in the concentration of free amino acids in the brain upon exposure to amnesia producing agents]. 56 6

Ketamine in dose 10 mg/kg increased the number of erroneous choices of rats with spatial strategy and didn't effect searching accuracy of rats with non-spatial strategy in 8-arm radial maze. Ketamine in doses 1 and 5 mg/kg disrupted rat short-term memory in delayed response reaction. Physostigmine and aspartic acid, but not haloperidol, diminished ketamine amnesia, therefore ketamine impaired the interaction of cholinergic and glutamate/aspartatergic neurons of hippocampal areas.
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PMID:[Pharmacological correction of ketamine-impaired spatial memory of rats]. 208 62

The model neurotic state in rats was formed within 1 month by the method of "conflict of afferent excitations". Piracetam and N-acetyl aspartic acid in doses of 250 and 50 mg/kg, respectively, administered intraperitoneally daily for the last 7 days of the experiment prevented the amnesia of the passive avoidance habit, which is typical of the developed abnormality in 60 and 40% of the rats, respectively (p < 0.05). The neurotic state was characterized by a significant increase of contents of inhibitory amino acids GABA and glycine in the brain cortex, GABA and glutamate in the hippocampus. Piracetam caused inversely directed changes of these parameters in the neuroticized animals.
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PMID:[The evaluation of the effects of piracetam and N-acetylaspartic acid on memory and the content of mediator amino acids in the brain in a model neurotic state in rats]. 831 44

We have previously shown that, after peripheral administration, different cytokines affect cognitive functions in mice. In this study, we evaluated the effects of mouse interleukin-6 (IL-6) on the classical behavioural test of scopolamine-induced amnesia for a passive avoidance response in the mouse. Pretraining i.p. administration of this cytokine (0.125 and 0.5 microgram/mouse) significantly reduced the amnesic action of the muscarinic receptor antagonist. As it is well known that brain amino acids are deeply involved in the modulation of cognitive processes we measured the levels of glutamine, aspartic acid, glutamic acid and GABA in the hippocampus and hypothalamus of mice treated with IL-6. At both doses which affected the cognitive functions, this cytokine had no effect on brain levels of measured amino acids. Neither nociceptive thresholds to a thermal stimulus, nor spontaneous locomotor activity were modified by the acute administration of IL-6 (0.5 microgram/mouse). Our data confirm previous observations indicating that peripheral administration of cytokines affects some, but not other brain functions and suggest the involvement of IL-6 in the central modifications induced by the immune activation.
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PMID:Interleukin-6 affects scopolamine-induced amnesia, but not brain amino acid levels in mice. 942 97

The discovery of the dipeptide gamma-glutamyltaurine (gamma-GT; glutaurine, Litoralon) in the parathyroid in 1980 and later in the brain of mammals gave rise to studies on intrinsic and synthetic taurine peptides of this type. It was suggested that gamma-glutamyltransferase (GGT; gamma-glutamyltranspeptidase) in the brain is responsible for the in vivo formation of this unusual dipeptide. gamma-GT has been prepared by both synthetic and enzymatic methods. The chemical syntheses included the use of protecting groups and coupling methods. A wide spectrum of analytical and spectroscopic methods was used to confirm the structure of the synthetic compounds and to elucidate the position of the peptide bond. Enzymatic preparation of gamma-GT from taurine takes advantage of the selective transpeptidation action of GGT on L-glutamine, glutathione, gamma-glutamyl-p-nitroanilide or other glutamine donors. Although the functional roles of gamma-GT in the brain are only poorly understood, many of its established CNS effects have been reported in the last 25 years. Its effect on emotional arousal and its anti-conflict potencies are synergistic with the anxiolytic drug diazepam. gamma-GT exhibits anti-conflict potency, which is exerted by reducing aversion or phobia and/or the anxiety levels. gamma-GT also acts as endogenous modulator in excitatory aminoacidergic neurotransmission. It is suggested that such acidic peptides through N-methyl-D-aspartic acid receptors could be part of the neurochemical substrate underlying self-stimulation of the medial prefrontal cortex. Other gamma-GT effects in neural systems include: effects on the monoamine concentration in the brain; effects on aggressive behavior in the cat; effects on thyroid hormones in the rat; amelioration of electroshock-induced amnesia; potent and long-lasting antiepileptic action (on intra-amygdaloid injection); affect the glutamatergic system in schizophrenic disorders. Roles for gamma-GT in non-neural systems have also been reported, e.g., effects on the metamorphosis of amphibians; on plasma rennin regulation; on radiation protection; on uric acid levels; on human antibody-dependent cell-mediated cytotoxicity (ADCC) and many more.
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PMID:gamma-L-glutamyltaurine. 1583 90

We studied the effect of activation (N-methyl-D-aspartic acid and D-cycloserine) and blockade (dizocilpine and 7-chlorokynurenic acid) of N-methyl-D-aspartate receptors on the development of amnesia in intact and depressive mice under conditions of conditioned passive avoidance response. Agonists and antagonists of N-methyl-D-aspartate receptors produce a strong antiamnesic effect in mice with behavioral despair. In intact animals, only N-methyl-D-aspartic acid and D-cycloserine improved passive avoidance performance.
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PMID:N-methyl-D-aspartate receptors and amnesia in mice with depression-like state. 1868 85

Infantile amnesia (i.e., the rapid rate of forgetting in young animals) is at least partially due to a memory retrieval, rather than a storage, failure as studies have shown that these engrams can continue to influence later behavior. For example, prior conditioning affects the neural mechanisms underlying future learning. In adult animals, the initial learning of a context-shock association depends upon N-Methyl-D-Aspartate (NMDA) receptors, but this conditioning renders subsequent learning to a similar context NMDAr-independent. In the present study, we examined whether this transition from NMDAr-dependent to NMDAr-independent context conditioning occurs even after infantile amnesia. Experiment 1 demonstrated that infant (i.e., postnatal day 17) rats acquire a context-shock association when trained with multiple shocks, as assessed by context freezing one day later. However, they exhibit significant forgetting of this association 10days later. Experiments 2 and 3 showed that even when animals had forgotten the initial learning experience, future conditioning to the same context was NMDAr-independent. There was evidence of a transition to NMDAr-independent context fear learning in animals exposed only to the foot shock in infancy (Experiment 3) or only to the context in infancy (Experiment 3 but not Experiment 2). These latter results suggest that animals do not have to be exposed to the entire conditioning procedure at postnatal day 17 to show a transition to NMDAr-independent context learning. These experiments add to a growing body of evidence that forgotten infant memories can continue to affect later behavior by demonstrating that prior experience alters the mechanisms of future learning.
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PMID:Relearning a context-shock association after forgetting is an NMDAr-independent process. 2544 98