* Persistent changes in neuronal structure and synaptic plasticity caused by proton irradiation.
- Cranial radiotherapy is used routinely to control the growth of primary and secondary brain tumors, but often results in serious and debilitating cognitive dysfunction. In part due to the beneficial dose depth distributions that may spare normal tissue damage, the use of protons to treat CNS and other tumor types is rapidly gaining popularity. Astronauts exposed to lower doses of protons in the space radiation environment are also at risk for developing adverse CNS complications. To explore the consequences of whole body proton irradiation, mice were subjected to 0.1 and 1 Gy and analyzed for morphometric changes in hippocampal neurons 10 and 30 days following exposure. Significant dose-dependent reductions (~33 %) in dendritic complexity were found, when dendritic length, branching and area were analyzed 30 days after exposure. At equivalent doses and times, significant reductions in the number (~30 %) and density (50-75 %) of dendritic spines along hippocampal neurons of the dentate gyrus were also observed. Immature spines (filopodia, long) exhibited the greatest sensitivity (1.5- to 3-fold) to irradiation, while more mature spines (mushroom) were more resistant to changes over a 1-month post-irradiation timeframe. Irradiated granule cell neurons spanning the subfields of the dentate gyrus showed significant and dose-responsive reductions in synaptophysin expression, while the expression of postsynaptic density protein (PSD-95) was increased significantly. These findings corroborate our past work using photon irradiation, and demonstrate for the first time, dose-responsive changes in dendritic complexity, spine density and morphology and synaptic protein levels following exposure to low-dose whole body proton irradiation.
=>1.低くする/なる, 下げる/下がる, 卑しめる, 2.しかめっ面, 3.lowの比較級
Overview of noun lower
The noun lower has 1 sense (no senses from tagged texts)
1. lower berth, lower -- (the lower of two berths)
Overview of verb lower
The verb lower has 5 senses (first 3 from tagged texts)
1. (15) lower, take down, let down, get down, bring down -- (move something or somebody to a lower
position; "take down the vase from the shelf")
2. (6) lower, lour -- (set lower; "lower a rating"; "lower expectations")
3. (1) turn down, lower, lour -- (make lower or quieter; "turn down the volume of a radio")
4. lower, depress -- (cause to drop or sink; "The lack of rain had depressed the water level in the
reservoir")
5. frown, glower, lour, lower -- (look angry or sullen, wrinkle one's forehead, as if to signal
disapproval)
Overview of adj low
The adj low has 10 senses (first 6 from tagged texts)
1. (55) low -- (less than normal in degree or intensity or amount; "low prices"; "the reservoir is
low")
2. (23) low -- (literal meanings; being at or having a relatively small elevation or upward
extension; "low ceilings"; "low clouds"; "low hills"; "the sun is low"; "low furniture"; "a low
bow")
3. (11) low, low-toned -- (very low in volume; "a low murmur"; "the low-toned murmur of the surf")
4. (6) low -- (unrefined in character; "low comedy")
5. (4) low, low-pitched -- (used of sounds and voices; low in pitch or frequency)
6. (3) abject, low, low-down, miserable, scummy, scurvy -- (of the most contemptible kind; "abject
cowardice"; "a low stunt to pull"; "a low-down sneak"; "his miserable treatment of his family"; "You
miserable skunk!"; "a scummy rabble"; "a scurvy trick")
7. humble, low, lowly, modest, small -- (low or inferior in station or quality; "a humble cottage";
"a lowly parish priest"; "a modest man of the people"; "small beginnings")
8. depleted, low -- (no longer sufficient; "supplies are low"; "our funds are depleted")
9. broken, crushed, humbled, humiliated, low -- (subdued or brought low in condition or status;
"brought low"; "a broken man"; "his broken spirit")
10. gloomy, grim, blue, depressed, dispirited, down, downcast, downhearted, down in the mouth, low,
low-spirited -- (filled with melancholy and despondency ; "gloomy at the thought of what he had to
face"; "gloomy predictions"; "a gloomy silence"; "took a grim view of the economy"; "the darkening
mood"; "lonely and blue in a strange city"; "depressed by the loss of his job"; "a dispirited and
resigned expression on her face"; "downcast after his defeat"; "feeling discouraged and
downhearted")
--- WordNet end ---