Elemental imaging shows mercury in cells of the human lateral and medial geniculate nuclei

Abstract

Interference with the transmission of sensory signals along visual and auditory pathways has been implicated in the pathogenesis of hallucinations. The relay centres for vision (the lateral geniculate nucleus) and hearing (the medial geniculate nucleus) appear to be susceptible to the uptake of circulating mercury. We therefore investigated the distribution of mercury in cells of both these geniculate nuclei. Materials and methods Paraffin-embedded tissue sections containing the lateral geniculate nucleus were obtained from 50 adults (age range 20-104 years) who at autopsy had a variety of clinicopathological conditions, including neurological and psychiatric disorders. The medial geniculate nucleus was present in seven sections. Sections were stained for mercury using autometallography. Laser ablation-inductively coupled plasma-mass spectrometry was used to confirm the presence of mercury. Results Ten people had mercury in cells of the lateral geniculate nucleus, and in the medial geniculate nucleus of three of these. Medical diagnoses in these individuals were: none (3), Parkinson disease (3), and one each of depression, bipolar disorder, multiple sclerosis, and mercury self-injection. Mercury was distributed in different groups of geniculate capillary endothelial cells, neurons, oligodendrocytes, and astrocytes. Mass spectrometry confirmed the presence of mercury. Conclusion Mercury is present in different combinations of cell types in the lateral and medial geniculate nuclei in a proportion of people from varied backgrounds. This raises the possibility that mercury-induced impairment of the function of the geniculate nuclei could play a part in the

Mercury is present in neurons and oligodendrocytes in regions of the brain affected by Parkinson’s disease and co-localises with Lewy bodies

“…Neurons . In the two people with PD, neurons containing cytoplasmic iHg were confirmed to be present in the locus ceruleus, and were also seen in some of the few surviving neurons of the substantia nigra compacta (referred to here as the substantia nigra), the frontal motor cortex (mostly corticomotoneurons/Betz cells), the striatum (medium-sized neurons in the caudate and putamen), thalamus, cerebellar cortex (Purkinje and granule cells), cerebellar dentate nucleus, lateral geniculate nucleus [ 32 ], dorsal raphe nucleus, cranial nerve motor nuclei 5, 6 and 7, dorsal vagal nucleus, nucleus ambiguus, and inferior olivary nucleus ( Figs 1 and 2 and Table 1 ). The distribution of mercury between the two PD patients mostly overlapped, but some variability was seen: PD1 did not have mercury in cranial nerve motor nuclei or amygdala neurons, and PD2 did not have cerebellar neuronal mercury.…”

“…In the professional fisherman (ME2), in addition to the locus ceruleus, neuronal iHg was seen in neurons of the lateral geniculate nucleus [ 32 ], cuneate and gracile nuclei, cranial nerve motor nucleus 4, inferior olivary nucleus, medullary reticular formation and cerebellar dentate nucleus ( Fig 3 ). Particulate mercury was seen adjacent to Purkinje cell bodies, possibly in Bergmann glia.…”

“…LA-ICP-MS of the posterior pons, lateral geniculate nucleus, facial motor nucleus, frontal lobe, hippocampus, and cerebellar hemisphere of PD2 showed mercury in regions where autometallography staining was positive, and did not detect mercury in autometallography-negative regions ( Figs 4 and S1 ). Mercury was detected in regions containing large amounts of autometallography-detected intraneuronal iHg, such as the locus ceruleus, lateral geniculate neurons [ 32 ] and facial motor neurons, and in the frontal and hippocampal white matter where oligodendrocytes contained autometallography-detected iHg. The locus ceruleus also contained iron, aluminium and nickel, which were not seen in other regions.…”

“…( 2 ) Visual hallucinations are frequent in PD, and can be a harbinger of future dementia [ 64 ]. Damage to the lateral geniculate nucleus, with disturbances of the visual pathway, may be triggered by mercury in geniculate neurons [ 32 ]. Both of our PD cases had marked uptake of mercury into lateral geniculate neurons.…”

Cellular and Molecular Mechanisms Mediating Methylmercury Neurotoxicity and Neuroinflammation

“…In this case, MeHg and Hg induced a dose-dependent loss of cell viability, with MeHg being more toxic [ 146 ]. A couple of recent studies on human brains denoted the accumulation of Hg inside the cerebral cortex and geniculate nuclei oligodendrocytes [ 147 , 148 ]. Mercury in oligodendrocytes may possibly affect axonal conductance and myelin metabolism which in turn have the ability to decelerate nerve impulses [ 147 ].…”