Ultrastructural investigation of microcalcification and the role of oxygen–glucose deprivation in cultured rat hippocampal slices

Riew, Tae-Ryong; Kim, Hong Lim; Shin, Yoo-Jin; Park, Joohee; Pak, Ha-Jin; Lee, Mun‐Yong

doi:10.1016/j.brainres.2015.06.048

Cited by 4 publications

(5 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, no calcium deposits were detected in the vacuoles by 28 days after reperfusion. These results are in agreement with our in vitro results [ 33 ] and with previous findings indicating that no calcium deposition occurs in liquefactive or total necrosis [ 34 ]. In contrast, some neurons in the pyramidal cell layer did not display either swelling or membrane disruption, but instead became dark and condensed and retained their compact ultrastructure.…”

Section: Discussionsupporting

confidence: 94%

“…Another intriguing observation in the present study was that most of the calcifying bodies were closely associated with or completely engulfed by astrocytes; thus, they appeared to be separated from the surrounding neurites at 28 days after reperfusion, while they were in direct juxtaposition to adjacent calcifying or non-calcifying neurites by 14 days after reperfusion. These results are consistent with our previous in vitro and in vivo studies showing that the mineralized cells are closely associated with astrocytes [ 33 , 41 , 42 ] and with other studies showing that astrocytes may be involved in regulating the mineralization of neighboring degenerating cells [ 12 , 42 , 46 ]. Therefore, it is possible that astrocytes (1) participate in the phagocytosis of calcium deposits, (2) form glial barriers that surround the calcified structures and sequester them, and (3) regulate mineralization in the ischemic hippocampus.…”

Section: Discussionsupporting

confidence: 93%

“…These “dark neurons” are observed even in undamaged environments either by a single electric shock or in the visibly intact hippocampus, in addition to in a necrotic or an excitotoxic environment such as those generated by ischemic insults or epilepsy [ 32 , 37 – 40 ]. Recently, we reported that mineralized cells were detected in control hippocampal slice cultures but not in oxygen-glucose-deprived hippocampal cultures [ 33 ]. It is interesting that these in vitro mineralized cells closely resemble the dark neurons observed in the present study in terms of the presence of selective calcium deposition within, but not beyond, the mitochondria and because they both exhibit the ultrastructural features of non-necrotic, non-apoptotic cell death and retain their compact ultrastructure.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Spatiotemporal Progression of Microcalcification in the Hippocampal CA1 Region following Transient Forebrain Ischemia in Rats: An Ultrastructural Study

et al. 2016

Self Cite

View full text Add to dashboard Cite

Calcification in areas of neuronal degeneration is a common finding in several neuropathological disorders including ischemic insults. Here, we performed a detailed examination of the onset and spatiotemporal profile of calcification in the CA1 region of the hippocampus, where neuronal death has been observed after transient forebrain ischemia. Histopathological examinations showed very little alizarin red staining in the CA1 pyramidal cell layer until day 28 after reperfusion, while prominent alizarin red staining was detected in CA1 dendritic subfields, particularly in the stratum radiatum, by 14 days after reperfusion. Electron microscopy using the osmium/potassium dichromate method and electron probe microanalysis revealed selective calcium deposits within the mitochondria of degenerating dendrites at as early as 7 days after reperfusion, with subsequent complete mineralization occurring throughout the dendrites, which then coalesced to form larger mineral conglomerates with the adjacent calcifying neurites by 14 days after reperfusion. Large calcifying deposits were frequently observed at 28 days after reperfusion, when they were closely associated with or completely engulfed by astrocytes. In contrast, no prominent calcification was observed in the somata of CA1 pyramidal neurons showing the characteristic features of necrotic cell death after ischemia, although what appeared to be calcified mitochondria were noted in some degenerated neurons that became dark and condensed. Thus, our data indicate that intrahippocampal calcification after ischemic insults initially occurs within the mitochondria of degenerating dendrites, which leads to the extensive calcification that is associated with ischemic injuries. These findings suggest that in degenerating neurons, the calcified mitochondria in the dendrites, rather than in the somata, may serve as the nidus for further calcium precipitation in the ischemic hippocampus.

show abstract

Section: Discussionsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Spatiotemporal Progression of Microcalcification in the Hippocampal CA1 Region following Transient Forebrain Ischemia in Rats: An Ultrastructural Study

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus, our data indicate that reactive astrocytes forming the astroglial scar are capable of phagocytosing OPN puncta in the lesioned striatum. Interestingly, OPN protein accumulates selectively on the surface of degenerating neurites that are filled with aggregated calcium crystals [8, 10, 16], and the distribution of the calcifying deposits was frequently observed in close proximity to, surrounded by, or sometimes within, hypertrophied reactive astrocytes, suggesting possible phagocytosis of calcium deposits by reactive astrocytes [9, 60, 61]. Therefore, it is plausible to conclude that degenerative calcifying neurites labeled by OPN were often phagocytosed by reactive astrocytes.…”

Section: Discussionmentioning

confidence: 99%

Osteopontin and its spatiotemporal relationship with glial cells in the striatum of rats treated with mitochondrial toxin 3-nitropropionic acid: possible involvement in phagocytosis

Riew

Kim

Jin

et al. 2019

J Neuroinflammation

Self Cite

View full text Add to dashboard Cite

Background Osteopontin (OPN, SPP1) is upregulated in response to acute brain injury, and based on its immunoreactivity, two distinct forms have been identified: intracellular OPN within brain macrophages and small granular OPN, identified as OPN-coated degenerated neurites. This study investigates the spatiotemporal relationship between punctate OPN deposition and astroglial and microglial reactions elicited by 3-nitropropionic acid (3-NP). Methods Male Sprague-Dawley rats were intraperitoneally injected with mitochondrial toxin 3-NP and euthanized at 3, 7, 14, and 28 days. Quantitative and qualitative light and electron microscopic techniques were used to assess the relationship between OPN and glial cells. Statistical significance was determined by Student’s t test or a one-way analysis of variance followed by Tukey’s multiple comparisons test. Results Punctate OPN-immunoreactive profiles were synthesized and secreted by amoeboid-like brain macrophages in the lesion core, but not by reactive astrocytes and activated microglia with a stellate shape in the peri-lesional area. Punctate OPN accumulation was detected only in the lesion core away from reactive astrocytes in the peri-lesional area at day 3, but had direct contact with, and even overlapped with astroglial processes at day 7. The distance between the OPN-positive area and the astrocytic scar significantly decreased from days 3 to 7. By days 14 and 28 post-lesion, when the glial scar was fully formed, punctate OPN distribution mostly overlapped with the astrocytic scar. Three-dimensional reconstructions and quantitative image analysis revealed numerous granular OPN puncta inside the cytoplasm of reactive astrocytes and brain macrophages. Reactive astrocytes showed prominent expression of the lysosomal marker lysosomal-associated membrane protein 1, and ultrastructural analysis confirmed OPN-coated degenerating neurites inside astrocytes, suggesting the phagocytosis of OPN puncta by reactive astrocytes after injury. Conclusions Punctate OPN-immunoreactive profiles corresponded to OPN-coated degenerated neurites, which were closely associated with, or completely engulfed by, the reactive astrocytes forming the astroglial scar in 3-NP lesioned striatum, suggesting that OPN may cause astrocytes to migrate towards these degenerated neurites in the lesion core to establish physical contact with, and possibly, to phagocytose them. Our results provide novel insights essential to understanding the recovery and repair of the central nervous system tissue. Electronic supplementary material The online version of this article (10.1186/s12974-019-1489-1) contains supplementary material, which is available to authorized users.

show abstract

“…Excess mitochondrial calcium can lead to intramitochondrial calcification, which is proposed to act as calcium deposit nucleation2230313233. These observations may lead us to speculate that OPN is involved in the onset of mineralisation, including in intracellular calcification, which occurs in degenerating neurons.…”

mentioning

confidence: 99%

Spatiotemporal expression of osteopontin in the striatum of rats subjected to the mitochondrial toxin 3-nitropropionic acid correlates with microcalcification

Riew

Kim

Jin

et al. 2017

Sci Rep

Self Cite

View full text Add to dashboard Cite

Our aim was to elucidate whether osteopontin (OPN) is involved in the onset of mineralisation and progression of extracellular calcification in striatal lesions due to mitochondrial toxin 3-nitropropionic acid exposure. OPN expression had two different patterns when observed using light microscopy. It was either localised to the Golgi complex in brain macrophages or had a small granular pattern scattered in the affected striatum. OPN labelling tended to increase in number and size over a 2-week period following the lesion. Ultrastructural investigations revealed that OPN is initially localised to degenerating mitochondria within distal dendrites, which were then progressively surrounded by profuse OPN on days 7–14. Electron probe microanalysis of OPN-positive and calcium-fixated neurites indicated that OPN accumulates selectively on the surfaces of degenerating calcifying dendrites, possibly via interactions between OPN and calcium. In addition, 3-dimensional reconstruction of OPN-positive neurites revealed that they are in direct contact with larger OPN-negative degenerating dendrites rather than with fragmented cell debris. Our overall results indicate that OPN expression is likely to correlate with the spatiotemporal progression of calcification in the affected striatum, and raise the possibility that OPN may play an important role in the initiation and progression of microcalcification in response to brain insults.

show abstract

Ultrastructural investigation of microcalcification and the role of oxygen–glucose deprivation in cultured rat hippocampal slices

Cited by 4 publications

References 55 publications

Spatiotemporal Progression of Microcalcification in the Hippocampal CA1 Region following Transient Forebrain Ischemia in Rats: An Ultrastructural Study

Spatiotemporal Progression of Microcalcification in the Hippocampal CA1 Region following Transient Forebrain Ischemia in Rats: An Ultrastructural Study

Osteopontin and its spatiotemporal relationship with glial cells in the striatum of rats treated with mitochondrial toxin 3-nitropropionic acid: possible involvement in phagocytosis

Spatiotemporal expression of osteopontin in the striatum of rats subjected to the mitochondrial toxin 3-nitropropionic acid correlates with microcalcification

Contact Info

Product

Resources

About