吡哆醇 (Pyridoxine)，為維生素B₆的化合物之一，作為日常保健食品使用，患有神經/心理障礙疾病（包括癲癇）的患者也被建議補充維生素B₆。然而高劑量的吡哆醇會導致感覺神經病變，包括感覺異常、瀰漫性感覺喪失、感覺性共濟失調和自主神經功能障礙。因此，了解高劑量吡哆醇的毒理學機制很重要。先前的實驗我們發現暴露於吡哆醇和丙戊酸 (VPA) 的斑馬魚幼魚在30 分鐘內快速死亡。丙戊酸是一種廣泛使用的藥物，用於治療癲癇和其他神經系統疾病。有趣的是，在體外實驗用吡哆醇和丙戊酸共同處理培養的細胞不會降低細胞存活率。在目前的研究中，我們旨在調查導致吡哆醇和丙戊酸共同暴露的幼魚快速死亡的機制。我們的結果表明，添加抗凋亡抑製劑可以有效防止吡哆醇和丙戊酸同時暴露幼魚的快速死亡，但不能有效預防壞死性凋亡。利用 TUNEL 試驗觀察到明顯的凋亡細胞訊號，但沒有台盼藍TNF-induced necroptosis也觀察到死亡率獲得明顯的下降。我們的結果表明，阻止鈣離子湧入進而降低細胞內鈣含量,可以顯著防止吡哆醇和丙戊酸誘導的快速死亡。此外，抑制肌醇三磷酸受體 (IP3R)其位於內質網表面的鈣通道，成功地減少幼魚從吡哆醇和丙戊酸共處理引起的死亡。同時，在吡哆醇和丙戊酸共同暴露的幼魚中觀察到線粒體跨膜電位的喪失。綜上所述，我們的結果表明鈣離子湧入及 IP3R 介導的細胞內鈣含量失衡可能誘導細胞凋亡途徑，這導致同時暴露於 吡哆醇和丙戊酸的幼魚死亡。

Pyridoxine (PN), also known as vitamin B6, is most commonly given as a vitamin B6 supplement and is consumed by the general public as well as patients with neurological/ psychological disorders, including epilepsy. However, high doses of PN can cause sensory neuropathy, including paresthesia, diffuse sensory loss, sensory ataxia, and autonomic dysfunction, in turn hampering the usefulness of pyridoxine. Therefore, understanding the toxicological mechanism underlying the high-dose consumption of pyridoxine is important. Previously, we found that zebrafish larvae exposed to PN and Valproic acid (VPA) simultaneously died within 30 minutes of exposure. VPA is a widely administered drug for the treatment of epilepsy and several other neurological disorders. Peculiarly, co-treating cultured cells with PN and VPA in vitro does not decrease cell survival. In the current study, we aimed toward an investigation of the mechanism that contributes to the quick death of PN/VPA co-exposed larvae. Our results showed that the quick death of PN/VPA co-exposed larvae was effectively prevented by adding an inhibitor against apoptosis, but not necroptosis. Apparent signals were observed with a TUNEL assay, but not trypan blue staining, supporting the occurrence of apoptosis. An appreciable rescue effect was also observed when EGTA was added to water with embryos. Our results also showed that blocking calcium influx to reduce [Ca2+]i can significantly prevent the quick death induced by PN/VPA. Furthermore, blocking the inositol trisphosphate receptor (IP3R), a calcium channel located on the surface of the ER membrane successfully rescued the larvae from death caused by the PN/VPA- cotreatment. At the same time, a loss in the mitochondrial transmembrane potential was observed in the PN/VPA co-exposed larvae. Taken together, our results suggest that a calcium influx and IP3R mediated [Ca2+]i -imbalance may have activated a apoptotic pathway that contributed to the death of larvae simultaneously exposed to PN and VPA.

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