Gastinger Matthew J, Yusupov Rafail G, Glickman Randolph D, Marshak David W
Graduate School of Biomedical Sciences, The University of Texas Health Science Center Houston, Houston, TX, USA.
Vis Neurosci. 2004 Nov-Dec;21(6):935-43. doi: 10.1017/S0952523804216133.
Mammalian retinas receive input from the posterior hypothalamus, and the neurotransmitter in this pathway is histamine. To determine whether histamine influences ganglion cells, we analyzed the effects of histamine on their maintained and light-evoked activity in vitro. In monkeys, histamine increased the maintained firing rate in 42% of ganglion cells, decreased it in 38%, and had no effect in 20%. When histamine and the HR3 agonist, methylhistamine, were applied to the same cells in succession, their effects were sometimes different, a finding suggesting that at least one other histamine receptor is present. In addition, the responses of some ganglion cells to full-field light stimuli were decreased by histamine and methylhistamine. In rats, the effects of histamine were somewhat different. Histamine increased the maintained firing rate of 82% of ganglion cells. Methylhistamine and the HR2 agonist, dimaprit, had the same effects as histamine. In some cells, histamine increased the light responses, but in others it decreased them. Histamine had no effect on ganglion cells in either species when synaptic transmission was blocked by low Ca2(+)/high Mg2+ Ames medium. Thus, the major effects of histamine were on the maintained activity of retinal ganglion cells. In both rats and monkeys, 80% or more of the ganglion cells were affected by histamine, and these responses were mediated by at least two of the histamine receptor subtypes.
哺乳动物的视网膜接收来自下丘脑后部的输入，该通路中的神经递质是组胺。为了确定组胺是否影响神经节细胞，我们在体外分析了组胺对其持续活动和光诱发活动的影响。在猴子中，组胺使42%的神经节细胞的持续放电率增加，38%的神经节细胞的持续放电率降低，20%的神经节细胞无变化。当依次将组胺和HR3激动剂甲基组胺应用于同一细胞时，它们的作用有时不同，这一发现表明至少存在一种其他组胺受体。此外，组胺和甲基组胺可降低一些神经节细胞对全视野光刺激的反应。在大鼠中，组胺的作用有所不同。组胺使82%的神经节细胞的持续放电率增加。甲基组胺和HR2激动剂二甲双胍与组胺具有相同的作用。在一些细胞中，组胺增加光反应，但在另一些细胞中则降低光反应。当用低钙/高镁的艾姆斯培养基阻断突触传递时，组胺对两种动物的神经节细胞均无影响。因此，组胺的主要作用是对视网膜神经节细胞的持续活动。在大鼠和猴子中，80%或更多的神经节细胞受组胺影响，这些反应由至少两种组胺受体亚型介导。
