Positron emission tomography in manganese intoxication

Abstract

We employed 6-fluorodopa to study the integrity of the nigrostriatal dopaminergic projection by positron emission tomography in 4 subjects with clinical features of mild parkinsonism caused by exposure to manganese. The 6-fluorodopa scans were normal. This finding suggests that in early manganism sufficient to cause parkinsonian deficits, damage may occur in pathways postsynaptic to the nigrostriatal system, probably involving striatal or pallidal neurons. Fluorodeoxyglucose scans showed decreased cortical glucose metabolism, the significance of which is discussed.

Neuroimaging in Manganese-Induced Parkinsonism

“…This finding is in accord with the 40-60% loss of dopaminergic cells seen in the nigrostriatal pathway of patients with IPD. In non-human primates and humans intoxicated with Mn, [ 18 F]-dopa (fluorodopa) PET scans are normal (Erikson et al, 1992;Kim et al, 1998;Shinotoh et al, 1995Shinotoh et al, , 1997Wolters et al, 1989). This supports the view that, in instances of Mn intoxication, the nigrostriatal pathway is relatively well preserved, consistent with many pathological observations showing that Mn-134 induced damage occurs primarily in pathways postsynaptic to the nigrostriatal system.…”

“…DAT SPECT is more easily accessible and less expensive than is fluorodopa PET. Fluorodopa and DAT uptake values are (nearly) normal in patients with manganism (Huang et al, 2003;Kim et al, 1998;Shinotoh et al, 1997;Wolters et al, 1989), whereas uptake is markedly reduced in IPD patients. However, Guilarte et al (2008) reported that, in the non-human primate brain, chronic Mn exposure inhibited dopaminergic transmission, leading to motor deficits, in the absence of changes to presynaptic dopaminergic nerve terminals.…”

An Assessment of the Distribution of Heavy Metals in the Riverine Sediments of Kortalaiyar River in Tamilnadu, India

“…It is predicted that fertilizer runoff is one of the predominant manmade sources of Mn enrichment in the riverine environment [18]. Zinc is present in high concentrations of 20 mg/kg -100.4 mg/kg in PRM and 20.3 mg/kg -95.4 mg/kg in POM.…”

Differential Role of Mitogen-Activated Protein Kinases in Response to Manganese Treatment in Substantia Nigra Dopaminergic Neurons

“…4) The relationship between Mn neurotoxicity and PD is still debated, but at least Mn exposure is a risk factor for PD. 6,7) The mechanisms of Mn neurotoxicty remain unclear. Earlier reports suggested that Mn could enhance autooxidation of catecholamines and generate reactive oxygen species 8) and inhibit mitochondrial aconitase activity and disrupt mitochondrial energy production in the brain.…”