Mercury in the human adrenal medulla could contribute to increased plasma noradrenaline in aging

Abstract

Plasma noradrenaline levels increase with aging, and this could contribute to the sympathetic overactivity that is associated with essential hypertension and the metabolic syndrome. The underlying cause of this rise in noradrenaline is unknown, but a clue may be that mercury increases noradrenaline output from the adrenal medulla of experimental animals. We therefore determined the proportion of people from 2 to 104 years of age who had mercury in their adrenal medulla. Mercury was detected in paraffin sections of autopsied adrenal glands using two methods of elemental bioimaging, autometallography and laser ablation-inductively coupled plasma-mass spectrometry. Mercury first appeared in cells of the adrenal medulla in the 21–40 years group, where it was present in 52% of samples, and increased progressively in frequency in older age groups, until it was detected in 90% of samples from people aged over 80 years. In conclusion, the proportion of people having mercury in their adrenal medulla increases with aging. Mercury could alter the metabolism of catecholamines in the adrenal medulla that leads to the raised levels of plasma noradrenaline in aging. This retrospective autopsy study was not able to provide a definitive link between adrenal mercury, noradrenaline levels and hypertension, but future functional human and experimental studies could provide further evidence for these associations.

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

“…Mercury can be taken up by thyroid follicular cells and could be responsible for the thyroid disorders that are found in about 10% of PD patients [ 21 , 82 ]. Mercury in the adrenal medulla may contribute to hypertension by raising noradrenaline levels [ 83 ] and therefore raise blood pressure in PD patients [ 77 , 78 ]. Pancreatic samples were not available for our PD cases, but mercury can be taken up by human pancreatic insulin-producing beta cells [ 16 ], so mercury exposure could contribute to the increased incidence of type 2 diabetes in PD [ 22 , 84 ].…”

The emotion paradox in the aging body and brain

“…With age, the adrenal medulla carries greater levels of toxic metals, such as mercury and cadmium. 93 Mercury poisoning increases sympathetic activity; for instance, it can lead to hypertension in children. [94][95][96] This has been hypothesized to be due to mercury deactivating the coenzyme S-adenosylmethionine (SAM), 94 which in turn decreases catechol-O-methyltransferase ability to deactivate noradrenaline and reduces phenylethanolamine N-methyltransferase ability to convert noradrenaline into adrenaline.…”

“…[94][95][96] This has been hypothesized to be due to mercury deactivating the coenzyme S-adenosylmethionine (SAM), 94 which in turn decreases catechol-O-methyltransferase ability to deactivate noradrenaline and reduces phenylethanolamine N-methyltransferase ability to convert noradrenaline into adrenaline. 93 Thus, by interfering with SAM, mercury deposits in the adrenal medulla are likely to increase noradrenaline output and decrease adrenaline output. Consistent with this profile, aging is associated with decreased adrenaline as well as increased noradrenaline.…”

“…With age, the adrenal medulla carries greater levels of toxic metals, such as mercury and cadmium 93 . Mercury poisoning increases sympathetic activity; for instance, it can lead to hypertension in children 94–96 .…”

Exposure to mercury and thyroid function: Is there a connection?

“…It is classified as a chemical that disrupts the endocrine system. Mercury exhibits harmful effects on reproductive health (9), contributes to the development of obesity (10), diabetes (11), affects the adrenal glands and the level of adrenal hormones in the plasma (12).…”