荷包牡丹碱对海马CA2区的神经毒性与P／Q型钙通道有关

目的：探讨荷包牡丹碱（BiC）对海马CA2区的神经毒性作用以及电压依赖性钙通道（VDCC）对神经毒性作用的影响。方法：BiC6μmol·L^-1刺激培养的大鼠海马组织72h，同时用N，L以及P／Q型钙通道拮抗剂分别阻断相应的钙通道，测定神经细胞摄取的碘化丙啶（PI）。结果：BiC刺激6h后，神经细胞的PI摄取首先出现在CA2区。随着BiC刺激时间的延长，摄取PI的神经细胞的分布范围由CA2区扩散到其他区域。P／Q型VDCC拮抗剂抑制神经细胞的PI摄取，然而N和L型VDCC的拮抗剂无明显抑制效果。结论：在大鼠海马的组织培养中CA2区的神经细胞对BiC的刺激最易受损。CA2区神经细胞的损伤过程中P／Q型VDCC起重要作用。

Bicuculline Induced Neurotoxicity of CA2 Sector Is Mediated by P/Q-type Voltage Dependent Ca~(2+) Channel in Rat Hippocampal Slice Culture

Aim： To study neuronal toxic effect of bicuculline （BiC） on CA2 sector and the type of voltage dependent calcium channel（VDCC） involved in the neuronal toxicity in hippocampal slice cultures. Methods： Slice cultures were prepared from Wistar rat pups postnatal day 7 and grown by the interface method for 6 days. The BiC was diluted to a final concentration of 6 μmol.L^-1 in culture medium and applied for 72 h. To determine the effects of the VDCCs on neuronal cell toxicity, 2 μmol.L^-1 ω-conotoxin GVIA, 2 μmol.L^-1 Nifedipin and 200 μmol.L^-1ω- agatoxin IVA, an N, L and P/Q type VDCC antagonists are employed respectively. The viability marker PI was used to evaluate the neuronal cell death in the slice cultures. The digital images were analyzed by using a densitometry analysis program. Results： After exposure to 6 μmol.L^-1 BiC for 6 h, the PI uptake first time appeared in the CA2 sector. The PI uptake increased with time, and its area seemed to extend to the CA3 sector.The PI uptake was significantly inhibited after 12 h in the presence of a P/Q type VDCC antagonist, however, N and L-type VDCC antagonists failed. Conclusion： CA2 is the most vulnerable sector in hippocampal slice cultures following exposure to BiC, and that the neuronal cell damage process involves a Ca^2＋ influx via P/Q- type VDCC.