Department of Physiology, School of Medicine, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
Cell Mol Neurobiol. 2018 Apr;38(3):757-767. doi: 10.1007/s10571-017-0542-9. Epub 2017 Aug 28.
The expression of H1 receptor has been reported in amacrine cells of mouse and rat retinae. However, we assumed that other types of histamine receptors also function in amacrine cells. In order to confirm that histamine modulates the membrane potential in mouse amacrine cells, we measured voltage-gated currents using whole-cell configuration. Under voltage-clamp conditions, the amplitude of voltage-gated outward currents was enhanced by the application of 100 µM histamine in 65% of amacrine cells. Histamine also increased the amplitudes of voltage-gated inward currents in 72% of amacrine cells. When antagonists of the histamine H1, H2, or H3 receptors were applied to histamine-sensitive amacrine cells, all three types of these inhibitors reduced the effect of histamine. Moreover, we classified recorded cells into seven types based on their morphological characteristics. Two of the seven types, diffuse multistratified cells and AII amacrine cells, responded significantly to histamine. These results indicate that histamine affected the membrane potential via three types of histamine receptors. Furthermore, there were differences in the responses to histamine among types of amacrine cells. Histamine may be one of the important neurotransmitters and/or neuromodulators in the visual processing.
H1 受体的表达已在鼠和大鼠视网膜的无长突细胞中被报道。然而，我们假设其他类型的组氨酸受体也在无长突细胞中起作用。为了证实组氨酸调节小鼠无长突细胞的膜电位，我们使用全细胞膜片钳构型测量了电压门控电流。在电压钳条件下，100μM 组氨酸的应用增强了 65%的无长突细胞的电压门控外向电流的幅度。组氨酸还增加了 72%的无长突细胞的电压门控内向电流的幅度。当组胺 H1、H2 或 H3 受体拮抗剂应用于组胺敏感的无长突细胞时，这三种抑制剂都降低了组胺的作用。此外，我们根据形态特征将记录的细胞分为七种类型。七种类型中的两种，弥散多分层细胞和 AII 无长突细胞，对组胺有显著反应。这些结果表明，组氨酸通过三种类型的组氨酸受体影响膜电位。此外，不同类型的无长突细胞对组胺的反应存在差异。组胺可能是视觉处理中的一种重要神经递质和/或神经调质。
