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Query: UMLS:C0751295 (memory loss)
 3,619 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It was observed by Couper in 1837 that manganese dust produces a neurological syndrome characterized by muscle weakness, tremor, bent posture, whispered speech and excess salivation. The similarity of these symptoms to those of Parkinson's disease were not recognized for many years. In addition to its Parkinson-like effects, manganese produces behavioral symptoms in humans including nervousness, hallucinations, memory loss, cognitive problems, bizarre behaviors and flight of ideas. Despite these signs and symptoms, there have been few systematic attempts to study the effects of manganese on behavior using animal models. The need to better understand the effects of manganese on behavior is becoming more important due to the potential of increased environmental exposure to manganese due to its use, or proposed use as a gasoline additive in a number of countries. However, there is debate as to which manganese compounds should receive priority for testing, what route of administration should be used in this testing, what dosing regimens should be used, what species are appropriate for behavioral testing, and what behavioral tests should be selected. Research to answer these questions is needed so that the behavioral effects of manganese can be described comprehensively and the mechanisms underlying these effects can be understood.
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PMID:A brief history of the neurobehavioral toxicity of manganese: some unanswered questions. 1038 8

Information on changes in the central nervous system (CNS) cholinergic systems following exposure to manganese are considerably less extensive than that associated with other neurotransmitter systems. However, experimental and clinical evidence support the notion that cholinergic activity plays a key role in the pathophysiology of manganese-induced neurotoxicity. Manganese acts as a chemical stressor in cholinergic neurons in a region-specific manner causing breakdown of the cellular homeostatic mechanisms. In fact, a number of cholinergic synaptic mechanisms are putative targets for manganese activity: presynaptic choline uptake, quantal release of acetylcholine into the synaptic cleft, postsynaptic binding of acetylcholine to receptors and its synaptic degradation by acetylcholinesterase. Moreover, manganese significantly influences astrocytic choline transport systems and astrocytic acetylcholine-binding proteins. Thus, manganese exerts its effect on the highly dynamic reciprocal relationship between astrocytes and cholinergic neurons. Cholinergic afferents are crucial in the physiology of locomotion, cognition, emotion and behavioral response, and therefore, it is not surprising that the anatomical selectivity of most manganese-induced cholinergic effects is compatible with the clinical correlates of manganism, which involves impairment of emotional response, decline in higher cortical functions and movement disorder. Manganism, also referred to as Parkinson's-like disorder, is initially manifested by a neuropsychiatric syndrome (locura manganica), the most frequent symptoms and signs of which are compulsive behavior, emotional lability, visual hallucinations and flight of ideas, cognitive decline and memory loss. These signs and symptoms are followed by an extrapyramidal syndrome, which shares numerous clinical and pathophysiological characteristics with idiopathic Parkinson's disease (PD). This natural history of disease could be a clinical reflection of the preferential involvement of the cholinergic systems, initially in the septo-hippocampus and later in the basal ganglia. These observations highlight the importance of studying the role of the CNS cholinergic systems in manganese-mediated neurotoxicity.
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PMID:Modulation of cholinergic systems by manganese. 1792 Jan 28

Excessive manganese (Mn) in the brain promotes a variety of abnormal behaviors, including memory deficits, decreased motor skills and psychotic behavior resembling Parkinson's disease. Hereditary hemochromatosis (HH) is a prevalent genetic iron overload disorder worldwide. Dysfunction in HFE gene is the major cause of HH. Our previous study has demonstrated that olfactory Mn uptake is altered by HFE deficiency, suggesting that loss of HFE function could alter manganese-associated neurotoxicity. To test this hypothesis, Hfe-knockout (Hfe (-/-)) and wild-type (Hfe (+/+)) mice mice were intranasally-instilled with manganese chloride (MnCl2 5 mg/kg) or water daily for 3 weeks and examined for memory function. Olfactory Mn diminished both short-term recognition and spatial memory in Hfe (+/+) mice, as examined by novel object recognition task and Barnes maze test, respectively. Interestingly, Hfe (-/-) mice did not show impaired recognition memory caused by Mn exposure, suggesting a potential protective effect of Hfe deficiency against Mn-induced memory deficits. Since many of the neurotoxic effects of manganese are thought to result from increased oxidative stress, we quantified activities of anti-oxidant enzymes in the prefrontal cortex (PFC). Mn instillation decreased superoxide dismutase 1 (SOD1) activity in Hfe (+/+) mice, but not in Hfe (-/-) mice. In addition, Hfe deficiency up-regulated SOD1 and glutathione peroxidase activities. These results suggest a beneficial role of Hfe deficiency in attenuating Mn-induced oxidative stress in the PFC. Furthermore, Mn exposure reduced nicotinic acetylcholine receptor levels in the PFC, indicating that blunted acetylcholine signaling could contribute to impaired memory associated with intranasal manganese. Together, our model suggests that disrupted cholinergic system in the brain is involved in airborne Mn-induced memory deficits and loss of HFE function could in part prevent memory loss via a potential up-regulation of anti-oxidant enzymes in the PFC.
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PMID:Loss of hfe function reverses impaired recognition memory caused by olfactory manganese exposure in mice. 2587 29

Excess manganese (Mn) is neurotoxic. Increased manganese stores in the brain are associated with a number of behavioral problems, including motor dysfunction, memory loss and psychiatric disorders. We previously showed that the transport and neurotoxicity of manganese after intranasal instillation of the metal are altered in Hfe-deficient mice, a mouse model of the iron overload disorder hereditary hemochromatosis (HH). However, it is not fully understood whether loss of Hfe function modifies Mn neurotoxicity after ingestion. To investigate the role of Hfe in oral Mn toxicity, we exposed Hfe-knockout (Hfe (-/-)) and their control wild-type (Hfe (+/+)) mice to MnCl2 in drinking water (5 mg/mL) for 5 weeks. Motor coordination and spatial memory capacity were determined by the rotarod test and the Barnes maze test, respectively. Brain and liver metal levels were analyzed by inductively coupled plasma mass spectrometry. Compared with the water-drinking group, mice drinking Mn significantly increased Mn concentrations in the liver and brain of both genotypes. Mn exposure decreased iron levels in the liver, but not in the brain. Neither Mn nor Hfe deficiency altered tissue concentrations of copper or zinc. The rotarod test showed that Mn exposure decreased motor skills in Hfe (+/+) mice, but not in Hfe (-/-) mice (p = 0.023). In the Barns maze test, latency to find the target hole was not altered in Mn-exposed Hfe (+/+) compared with water-drinking Hfe (+/+) mice. However, Mn-exposed Hfe (-/-) mice spent more time to find the target hole than Mn-drinking Hfe (+/+) mice (p = 0.028). These data indicate that loss of Hfe function impairs spatial memory upon Mn exposure in drinking water. Our results suggest that individuals with hemochromatosis could be more vulnerable to memory deficits induced by Mn ingestion from our environment. The pathophysiological role of HFE in manganese neurotoxicity should be carefully examined in patients with HFE-associated hemochromatosis and other iron overload disorders.
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PMID:Effect of Hfe Deficiency on Memory Capacity and Motor Coordination after Manganese Exposure by Drinking Water in Mice. 2687 37

Though an essential metal in the body, manganese (Mn) has a number of health implications when found in excess that are magnified by chronic exposure. These health complications include neurotoxicity, memory loss, infertility in males, and development of a neurologic psychiatric disorder, manganism. Thus, trace detection in environmental samples is increasingly important. Few electrode materials are able to reach the negative reductive potential of Mn required for anodic stripping voltammetry (ASV), so cathodic stripping voltammetry (CSV) has been shown to be a viable alternative. We demonstrate Mn CSV using an indium tin oxide (ITO) working electrode both bare and coated with a sulfonated charge selective polymer film, polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-sulfonate (SSEBS). ITO itself proved to be an excellent electrode material for Mn CSV, achieving a calculated detection limit of 5 nM (0.3 ppb) with a deposition time of 3 min. Coating the ITO with the SSEBS polymer was found to increase the sensitivity and lower the detection limit to 1 nM (0.06 ppb). This polymer modified electrode offers excellent selectivity for Mn as no interferences were observed from other metal ions tested (Zn(2+), Cd(2+), Pb(2+), In(3+), Sb(3+), Al(3+), Ba(2+), Co(2+), Cu(2+), Ni(3+), Bi(3+), and Sn(2+)) except Fe(2+), which was found to interfere with the analytical signal for Mn(2+) at a ratio 20:1 (Fe(2+)/Mn(2+)). The applicability of this procedure to the analysis of tap, river, and pond water samples was demonstrated. This simple, sensitive analytical method using ITO and SSEBS-ITO could be applied to a number of electroactive transition metals detectable by CSV.
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PMID:Bare and Polymer-Coated Indium Tin Oxide as Working Electrodes for Manganese Cathodic Stripping Voltammetry. 2698 Mar 22