43 research outputs found
神經保護藥物對粒線體功能異常時鼠腦病變的影響
3-Nitropropionic acid (3-NP)為粒線體
呼吸鏈複合體II 的抑制劑,它可在鼠導致
選擇性紋狀體病變,如同人類的Huntington
病。過去的許多研究包括我們的研究顯
示, 抑制興奮性氨基酸的釋放和施予
NMDA 受體的拮抗物,會減輕粒線體毒物
引起的腦病變。最近的研究也顯示,
Dichloroacetate (DCA)對心臟衰竭及腦缺
血的鼠有保護作用。DCA 也被用於治療粒
線體腦病變。為了更進一步了解DCA 是否
也可用於減輕3-NP 所致的腦病變,及這些
藥物對腦代謝物的影響,在本計畫中,我
們利用磁共振影像(MRI)(T2 圖譜)和生物
活體磁共振質譜(in vivo 1H MRS)的變化來
評估DCA 對粒線體功能異常所引發腦病
變的治療效果。我們以3-NP 為實驗藥物,
以迷你注射器包埋於二個月大的Sprague-
Dawley 株鼠腹部皮下, 並以MK-
801(2mg/kg)和DCA (100mg/kg)為治療藥
物,比較治療的效果。我們先觀察慢性3-
NP 注射對鼠行為和腦病變的影響。然後觀
察DCA 對亞急性3-NP 腦病變的影響。結
果顯示慢性3-NP 注射可使鼠產生肢體障
礙類似Huntington 病,如同亞急性注射。
同時鼠腦紋狀體也會產生病變。生物活體
磁共振質譜也顯示NAA 下降,表示神經元
的死亡。於亞急性的動物模式中,DCA 的
治療並不減輕3-NP 對鼠腦紋狀體的傷
害。DCA 的臨床運用需更進一步的深入探
討其可行性。Systemic injection of 3-nitropropionic
acid (3-NP), an irreversible inhibitor of
complex II in mitochondrial respiratory chain,
induces selective striatal lesions in rats and
non-human primates mimicking those in
Huntington’s disease. In recent studies,
dichloroacetate (DCA) was shown to have
protective effects in rat models of cerebral
ischemia and myocardial dysfunction.
However, its therapeutic effect on brain
lesions induced by mitochondrial dysfunction
is rarely investigated. In the past year, we
established an in vivo animal model to
evaluate the rat brain lesions in
mitochondrial dysfuction. In the present
study, we compared the therapeutic effect of
DCA and MK-801 by in vivo animal model.
Two-month-old Sprague-Dawley rats
were treated with 3-NP by continuous drug
release from mini-pump, implanted
subcutaneously. MK-801 (2mg/kg) and DCA
(100mg/kg) were given in the same way. The
rats were then evaluated by MRI (T2 maps)
and in vivo 1H-MRS at indicated time points.
We first evaluated the effect of chronic 3-NP
injection on rats, and then evaluated the
effect of DCA on the striatal lesions induced
by 5-day 3-NP injection. The results showed
that chronic 3-NP injection produced
behavioral change and selective striatal
lesions on rats. MRS also showed the decline
of NAA/Cr ratio, indicating the neuronal loss
or dysfunction. The simultaneous application
of DCA showed no attenuation of the striatal
lesions. The present results suggest that the application of DCA in brain lesions induced
by mitochondrial inhibitors need further
investigation
粒線體功能異常對人體神經細胞的影響(2/2)
3-Nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase, induced ATP depletion and both necrosis and apoptosis in human NT2-N neurons. Necrosis occurred predominantly during the first 2 days in a dose-dependent manner, whereas apoptosis was observed after 24 hr or later at a low constant rate in 0.1mM as well as 5mM 3-NP. We assayed the intracellular concentration of Ca24- ([Ca2j1) during the first 48 hours in 1mM 3-NP, a period during which 10% of the neurons died by necrosis and 3% by apoptosis. During the first 2 hours in 3-NP, all NT2-N neurons showed [Ca2j1 rise from48¡Ó2 to 140¡Ó l2nM(mean¡ÓSEM¡¦). After 24 and 48 hours in 3-NP, however, [Ca24-J remained above IOOnM in only 17% and 25% of the NT2-N neurons, respectively, suggesting that most neurons
were able to correct this early rise in [Ca24-], despite severe ATP depletion, and to survive. Activation of NMDA-GIuR contributed substantially to 3-NP-induced ATP depletion, and subsequent chronic elevation of [Ca24-]1 in the NT2-N neurons. We also demonstrated that blocking endoplasmic reticulum (ER) Ca24- release enhanced the capacity of these human neurons to maintain [Ca21], homeostasis and resist necrosis while subjected to chronic energy deprivation
粒線體與神經細胞死亡的研究(1/2)
粒線體功能異常會引起許多不同年齡層的神經病變。過去的研究顯示,
3-nitropropionic acid 所導致的神經細胞死亡與caspases 的活化有關。動物的研究顯示,
安非他命和甲基安非他命也會使紋狀體神經細胞退化死亡。然而這些神經細胞死亡的機
轉目前並不很清楚。產生過多的自由基是一個可能的機轉,另外也有研究顯示安非他命
和甲基安非他命可能影響粒線體的功能。因此,在本實驗中我們利用鼠腦初級皮質神經
細胞培養來探討導致安非他命和甲基安非他命神經毒性的原因。並比較與
3-nitropropionic acid 所導致神經細胞死亡的差異。我們發現安非他命和甲基安非他命都
可導致神經細胞死亡,且僅引起輕微caspase-3 的活化。證明安非他命和甲基安非他命
可以導致細胞壞死與細胞凋零。另外安非他命和甲基安非他命也使細胞自由基的產量增
加,尤其甲基安非他命所導致的增加更大,證明自由基的產量增加是導致神經細胞死亡
的主因之一。由於caspase-3 的活化發生於粒線體膜電位去極化後,因此主要發生於細
胞色素c 釋放之後。這一點與3-nitropropionic acid 有所差異。我們將繼續探討安非他命
和甲基安非他命的神經毒性,和釐清caspase-3 的活化是否的確會影響粒線體功能,而
更進一步了解3-nitropropionic acid 與安非他命和甲基安非他命神經毒性差異的地方。3-Nitropropionic acid (3-NP) is an irreversible inhibitor of succinate dehydrogenase.
Previous studies had shown that 3-NP can lead to neuronal death following the activation of
caspases. In the present study, we first investigate the neurotoxicity of methamphetamine and
amphetamine in primary rat cortical neuronal cultures, and will compare the pathogenetic mechanisms of neuronal death in methamphetamine and amphetamine with those in 3-NP. We
found that there was a dose- and time-dependent increase of neuronal death following the
application of methamphetamine and amphetamine. Only mild activation of caspase-3 was
found following the treatment, indicating that both methamphetamine and amphetamine can
result in apoptosis and necrosis. The caspase-3 activation developed following mitochondrial
depolarization, which was different from that in 3-NP. Significant elevation of reactive
oxygen species was found post the application of the drugs, especially in methamphetamine.
It suggests that increase of reactive oxygen species is one of the major pathogenic
mechanisms of neuronal death for both amphetamine and methamphetamine. In the following
year, works will be focused on the differences of neurotoxicity in both 3-NP and
methamphetamine (and amphetamine). Whether caspase-3 activation can really affect
mitochondrial function as that in 3-NP neurotoxicity will also be investigated
粒線體與神經細胞死亡的研究(2/2)
粒線體功能異常會引起許多不同年齡層
的神經病變。過去的研究顯示,3-nitropropionic
acid 與許多神經毒物包括安非他命和甲基安非
他命一樣會導致神經細胞死亡。而這些神經細
胞的死亡與caspases 的活化有關。另外產生過
多的自由基也是一個可能的機轉。過去的研究
顯示,caspase 的活化通常因為粒線體功能的異
常所引起。因此,在本實驗中我們利用鼠腦初
級皮質神經細胞培養來探討導致這些神經毒
物神經毒性的原因。並比較這些神經細胞的死
亡導致caspases 活化的差異。我們第一年的研
究發現安非他命和甲基安非他命所導致神經
細胞死亡可使細胞自由基的產量增加,尤其甲
基安非他命所導致的增加更大,並造成細胞壞
死與細胞凋零。然而安非他命和甲基安非他命
僅引起輕微caspase-3 的活化。我們進一步發
現,施與少量3-nitropropionic acid 可使經安非
他命和甲基安非他命處理的細胞ATP 大量下
降,證明安非他命和甲基安非他命會影響粒線
體功能。我們接著比較發現安非他命和甲基安
非他命處理的細胞其caspase-3 的活化發生於
粒線體膜電位去極化後,而3-nitropropionic
acid 處理的細胞其caspase-3 的活化發生於粒
線體膜電位去極化前即已進行。證明
3-nitropropionic acid 與安非他命和甲基安非他
命在caspase-3 的活化上是不一樣的。由於
3-nitropropionic acid 本身為粒線體毒物且會影
響Kreb cycle,是否因而誘發其他與粒線體無
關的caspase-3 活化值得進一步研究。相反的,
安非他命和甲基安非他命所導致神經細胞死
亡主要與自由基的產量增加有關,並進而影響
粒線體膜電位去極化。是否其他間接影響粒線
體膜電位去極化的神經毒物其caspase-3 活化
都與安非他命和甲基安非他命一樣發生於粒
線體膜電位去極化後值得進一步研究。3-Nitropropionic acid (3-NP) is an
irreversible inhibitor of succinate dehydrogenase.
Previous studies had shown that 3-NP can lead to
neuronal death following the activation of
caspases. In the present study, we first
investigate the neurotoxicity of
methamphetamine and amphetamine in primary
rat cortical neuronal cultures, and will compare
the pathogenic mechanisms of neuronal death in
methamphetamine and amphetamine with those
in 3-NP. We found that there was a dose- and
time-dependent increase of neuronal death
following the application of methamphetamine
and amphetamine. Significant elevation of
reactive oxygen species was also found after the
application of the drugs, especially in
methamphetamine. Addition of low
concentration of 3-NP significantly decreased the
cellular ATP in amphetamine-treated neurons,
indicating the effect of the drug on mitochondrial
function. However, compared with that in 3-NP
neurotoxicity, only mild activation of caspase-3
was found following the treatment of
amphetamine. We further found that the
caspase-3 activation in amphetamine and
methamphetamine developed following
mitochondrial depolarization. On the contrary,
the caspase-3 activation in 3-NP developed
before mitochondrial depolarization, indicating
both a mitochondrial-dependent and independent
pathways in 3-NP neurotoxicity. Because 3-NP is
a direct mitochondrial toxins while amphetamine
and methamphetamine are both indirect
mitochondrial toxins, whether that’s one of the
reasons leading to different caspase-3 activation
needs further investigation