Simultaneous monitoring of cerebral metal accumulation in an experimental model of Wilson’s disease by laser ablation inductively coupled plasma mass spectrometry

Abstract

BackgroundNeuropsychiatric affection involving extrapyramidal symptoms is a frequent component of Wilson’s disease (WD). WD is caused by a genetic defect of the copper (Cu) efflux pump ATPase7B. Mouse strains with natural or engineered transgenic defects of the Atp7b gene have served as model of WD. These show a gradual accumulation and concentration of Cu in liver, kidneys, and brain. However, still little is known about the regional distribution of Cu inside the brain, its influence on other metals and subsequent pathophysiological mechanisms. We have applied laser ablation inductively coupled plasma mass spectrometry and performed comparative metal bio-imaging in brain sections of wild type and Atp7b null mice in the age range of 11–24 months. Messenger RNA and protein expression of a panel of inflammatory markers were assessed using RT-PCR and Western blots of brain homogenates.ResultsWe could confirm Cu accumulation in brain parenchyma by a factor of two in WD (5.5 μg g−1 in the cortex) vs. controls (2.7 μg g−1) that was already fully established at 11 months. In the periventricular regions (PVR) known as structures of prominent Cu content, Cu was reduced in turn by a factor of 3. This corroborates the view of the PVR as efflux compartments with active transport of Cu into the cerebrospinal fluid. Furthermore, the gradient of Cu increasing downstream the PVR was relieved. Otherwise the architecture of Cu distribution was essentially maintained. Zinc (Zn) was increased by up to 40% especially in regions of high Cu but not in typical Zn accumulator regions, a side effect due to the fact that Zn is to some degree a substrate of Cu-ATPases. The concentrations of iron (Fe) and manganese (Mn) were constant throughout all regions assessed. Inflammatory markers TNF-α, TIMP-1 and the capillary proliferation marker α-SMA were increased by a factor of 2–3 in WD.ConclusionsThis study confirmed stable cerebral Cu accumulation in parenchyma and discovered reduced Cu in cerebrospinal fluid in Atp7b null mice underlining the diagnostic value of micro-local analytical techniques.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2202-15-98) contains supplementary material, which is available to authorized users.

Loss of divalent metal transporter 1 function promotes brain copper accumulation and increases impulsivity

“…Notably, Atp7b‐deficient mice, an animal model of WD, display age‐associated copper accumulation in the brain; brain Cu level does not differ at the age of 2‐month‐old between Atp7b‐deficient and wild‐type mice, but increases 50–130% in Atp7b‐deficient mice when they become 11–24 months old (Boaru et al . ). Our b/b rats exhibit increased brain Cu (up to 50%) at the age of 4 months old, providing a relevant rat model of WD, potentially with early onset.…”

“…Since Cu was consistently elevated across the brain regions with brain non-heme iron unchanged in b/b rats, we speculate that increased brain copper plays a significant role in the progression of abnormal emotional behavior. Notably, Atp7b-deficient mice, an animal model of WD, display age-associated copper accumulation in the brain; brain Cu level does not differ at the age of 2-month-old between Atp7b-deficient and wild-type mice, but increases 50-130% in Atp7b-deficient mice when they become 11-24 months old (Boaru et al 2014). Our b/b rats exhibit increased brain Cu (up to 50%) at the age of 4 months old, providing a relevant rat model of WD, potentially with early onset.…”

Trace metal imaging in diagnostic of hepatic metal disease

“…It is known that patients suffering from WD or HFE may develop fibrosis, cirrhosis or hepatocellular carcinoma. The accumulation of metal in fibrotic livers and in livers and brains that were taken from experimental models of WD were recently proven (Becker, ; M‐M et al, , ; Boaru et al, , ). Making use of SEM‐EDX it was possible to identify individual metal deposits, but it was not possible to distinguish between normal, fibrotic or cirrhotic liver tissue (from non‐WD patients) or not even identify the metal species because several elements have overlapping peaks and for data interpretation highly experienced investigators are required.…”

Animal models of Wilson disease

“…; Lutsenko ; Boaru et al . ). Atp7b −/− brains also show signs of oxidative stress as well as respiratory chain dysfunction (Sauer et al .…”