Spatiotemporal distribution of spectrin breakdown products induced by anoxia in adult rat optic nerve in vitro
Hypoxic/ischemic and traumatic injury to central nervous system myelinated axons is heavily dependent on accumulation of Ca ions in the axoplasm, itself promoted by Na influx from the extracellular space. Given the high density of nodal Na channels, we hypothesized that nodes of Ranvier might be particularly vulnerable to Ca overload and subsequent damage, as this is the expected locus of maximal Na influx. Adult rat optic nerves were exposed to in vitro anoxia and analyzed immunohistochemically for the presence of spectrin breakdown. Cleavage of spectrin became detectable between 15 and 30 mins of anoxia, and increased homogeneously along the lengths of fibers; localized breakdown was not observed at nodes of Ranvier at any time point analyzed. Spectrin breakdown was also found in glial processes surrounding axons. Confocal imaging of axoplasmic Ca also revealed a gradual and nonlocalized increase as anoxia progressed, without evidence of Ca 'hot-spots' anywhere along the axons at any time between 0 and 30 mins of anoxic exposure in vitro. Calculations of Ca diffusion rates indicated that even if Ca entered or was released focally in axons, this ion would diffuse rapidly into the internodes and likely produce diffuse injury by activating Ca-dependent proteases. Western blot analysis for voltage-gated Na channel protein revealed that key functional proteins such as these are also degraded by anoxia/ischemia. Thus, proteolysis of structural and functional proteins will conspire to irreversibly injure central axons and render them nonfunctional, eventually leading to transection, degradation, and Wallerian degeneration.
| Medienart: |
Artikel |
|---|
| Erscheinungsjahr: |
2006 |
|---|---|
| Erschienen: |
2006 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:26 |
|---|---|
| Enthalten in: |
Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism - 26(2006), 6 vom: 11. Juni, Seite 777-86 |
| Sprache: |
Englisch |
|---|
| Beteiligte Personen: |
Jette, Nathalie [VerfasserIn] |
|---|
| Themen: |
12634-43-4 |
|---|
| Anmerkungen: |
Date Completed 18.07.2006 Date Revised 28.11.2016 published: Print Citation Status MEDLINE |
|---|
| Förderinstitution / Projekttitel: |
|
|---|
| PPN (Katalog-ID): |
NLM157778045 |
|---|
| LEADER | 01000naa a22002652 4500 | ||
|---|---|---|---|
| 001 | NLM157778045 | ||
| 003 | DE-627 | ||
| 005 | 20231223080900.0 | ||
| 007 | tu | ||
| 008 | 231223s2006 xx ||||| 00| ||eng c | ||
| 028 | 5 | 2 | |a pubmed24n0526.xml |
| 035 | |a (DE-627)NLM157778045 | ||
| 035 | |a (NLM)16163297 | ||
| 040 | |a DE-627 |b ger |c DE-627 |e rakwb | ||
| 041 | |a eng | ||
| 100 | 1 | |a Jette, Nathalie |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Spatiotemporal distribution of spectrin breakdown products induced by anoxia in adult rat optic nerve in vitro |
| 264 | 1 | |c 2006 | |
| 336 | |a Text |b txt |2 rdacontent | ||
| 337 | |a ohne Hilfsmittel zu benutzen |b n |2 rdamedia | ||
| 338 | |a Band |b nc |2 rdacarrier | ||
| 500 | |a Date Completed 18.07.2006 | ||
| 500 | |a Date Revised 28.11.2016 | ||
| 500 | |a published: Print | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a Hypoxic/ischemic and traumatic injury to central nervous system myelinated axons is heavily dependent on accumulation of Ca ions in the axoplasm, itself promoted by Na influx from the extracellular space. Given the high density of nodal Na channels, we hypothesized that nodes of Ranvier might be particularly vulnerable to Ca overload and subsequent damage, as this is the expected locus of maximal Na influx. Adult rat optic nerves were exposed to in vitro anoxia and analyzed immunohistochemically for the presence of spectrin breakdown. Cleavage of spectrin became detectable between 15 and 30 mins of anoxia, and increased homogeneously along the lengths of fibers; localized breakdown was not observed at nodes of Ranvier at any time point analyzed. Spectrin breakdown was also found in glial processes surrounding axons. Confocal imaging of axoplasmic Ca also revealed a gradual and nonlocalized increase as anoxia progressed, without evidence of Ca 'hot-spots' anywhere along the axons at any time between 0 and 30 mins of anoxic exposure in vitro. Calculations of Ca diffusion rates indicated that even if Ca entered or was released focally in axons, this ion would diffuse rapidly into the internodes and likely produce diffuse injury by activating Ca-dependent proteases. Western blot analysis for voltage-gated Na channel protein revealed that key functional proteins such as these are also degraded by anoxia/ischemia. Thus, proteolysis of structural and functional proteins will conspire to irreversibly injure central axons and render them nonfunctional, eventually leading to transection, degradation, and Wallerian degeneration | ||
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Research Support, N.I.H., Extramural | |
| 650 | 4 | |a Research Support, Non-U.S. Gov't | |
| 650 | 7 | |a Sodium Channels |2 NLM | |
| 650 | 7 | |a Spectrin |2 NLM | |
| 650 | 7 | |a 12634-43-4 |2 NLM | |
| 650 | 7 | |a Calcium |2 NLM | |
| 650 | 7 | |a SY7Q814VUP |2 NLM | |
| 700 | 1 | |a Coderre, Elaine |e verfasserin |4 aut | |
| 700 | 1 | |a Nikolaeva, Maria A |e verfasserin |4 aut | |
| 700 | 1 | |a Enright, Paula D |e verfasserin |4 aut | |
| 700 | 1 | |a Iwata, Akira |e verfasserin |4 aut | |
| 700 | 1 | |a Smith, Douglas H |e verfasserin |4 aut | |
| 700 | 1 | |a Jiang, Qiubo |e verfasserin |4 aut | |
| 700 | 1 | |a Stys, Peter K |e verfasserin |4 aut | |
| 773 | 0 | 8 | |i Enthalten in |t Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism |d 1993 |g 26(2006), 6 vom: 11. Juni, Seite 777-86 |w (DE-627)NLM012901814 |x 1559-7016 |7 nnns |
| 773 | 1 | 8 | |g volume:26 |g year:2006 |g number:6 |g day:11 |g month:06 |g pages:777-86 |
| 912 | |a GBV_USEFLAG_A | ||
| 912 | |a GBV_NLM | ||
| 951 | |a AR | ||
| 952 | |d 26 |j 2006 |e 6 |b 11 |c 06 |h 777-86 | ||