Laboratory of Brain Development, and Repair, Biggs Institute for Alzheimer and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas, United States of America.
Department of Molecular Medicine, University of South Florida, Tampa, Florida, United States of America.
PLoS One. 2020 Jul 23;15(7):e0223633. doi: 10.1371/journal.pone.0223633. eCollection 2020.
Small conductance, calcium-activated (SK3) potassium channels control the intrinsic excitability of dopaminergic neurons (DN) in the midbrain and modulate their susceptibility to toxic insults during development.
We evaluated the age-dependency of the neuroprotective effect of an SK3 agonist, 1-Ethyl-1,3-dihydro-2H-benzimidazol-2-one (1-EBIO), on Amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) excitotoxicity to DN in ventral mesencephalon (VM) organotypic cultures.
Most tyrosine hydroxylase (TH)+ neurons were also SK3+; SK3+/TH- cells (DN+) were common at each developmental stage but more prominently at day in vitro (DIV) 8. Young DN+ neurons were small bipolar and fusiform, whereas mature ones were large and multipolar. Exposure of organotypic cultures to AMPA (100 μm, 16 h) had no effect on the survival of DN+ at DIV 8, but caused significant toxicity at DIV 15 (n = 15, p = 0.005) and DIV 22 (n = 15, p<0.001). These results indicate that susceptibility of DN to AMPA excitotoxicity is developmental stage-dependent in embryonic VM organotypic cultures. Immature DN+ (small, bipolar) were increased after AMPA (100 μm, 16 h) at DIV 8, at the expense of the number of differentiated (large, multipolar) DN+ (p = 0.039). This effect was larger at DIV 15 (p<<<0.0001) and at DIV 22 (p<<<0.0001). At DIV 8, 30 μM 1-EBIO resulted in a large increase in DN+. At DIV 15, AMPA toxicity was prevented by exposure to 30 μM, but not 100 μM 1-EBIO. At DIV 22, excitotoxicity was unaffected by 30 μM 1-EBIO, and partially reduced by 100 μM 1-EBIO.
The effects of the SK3 channel agonist 1-EBIO on the survival of SK3-expressing dopaminergic neurons were concentration-dependent and influenced by neuronal developmental stage.
小电导、钙激活（SK3）钾通道控制中脑多巴胺能神经元（DN）的固有兴奋性，并调节其在发育过程中对毒性损伤的易感性。
我们评估了 SK3 激动剂 1-乙基-1,3-二氢-2H-苯并咪唑-2-酮（1-EBIO）对氨基-3-羟基-5-甲基异恶唑-4-丙酸（AMPA）对 DN 兴奋性毒性的神经保护作用的年龄依赖性，在腹侧中脑（VM）器官型培养物中。
大多数酪氨酸羟化酶（TH）+神经元也是 SK3+；SK3+/TH-细胞（DN+）在每个发育阶段都很常见，但在体外培养第 8 天（DIV）更为明显。年轻的 DN+神经元呈小双极和梭形，而成熟的神经元呈大而多极形。在 DIV 8 时，器官型培养物暴露于 AMPA（100 μm，16 h）对 DN+的存活没有影响，但在 DIV 15（n = 15，p = 0.005）和 DIV 22（n = 15，p<0.001）时会导致明显的毒性。这些结果表明，DN 对 AMPA 兴奋性毒性的敏感性在胚胎 VM 器官型培养物中是发育阶段依赖性的。在 DIV 8 时，100 μm AMPA（16 h）后，DN+的数量增加（p = 0.039），而成熟的 DN+（大、多极）数量减少。在 DIV 15 时（p<<<0.0001）和 DIV 22 时（p<<<0.0001），这种影响更大。在 DIV 8 时，30 μM 1-EBIO 导致 DN+大量增加。在 DIV 15 时，暴露于 30 μM 1-EBIO 可预防 AMPA 毒性，但 100 μM 1-EBIO 则无效。在 DIV 22 时，30 μM 1-EBIO 对兴奋性毒性无影响，而 100 μM 1-EBIO 则部分减轻了毒性。
SK3 通道激动剂 1-EBIO 对表达 SK3 的多巴胺能神经元存活的影响呈浓度依赖性，并受神经元发育阶段的影响。
