Balaram Pooja, Hackett Troy A, Kaas Jon H
Department of Psychology, Vanderbilt University, Nashville, TN, USA.
Eye Brain. 2011 Dec;2011(3):81-98. doi: 10.2147/EB.S23007.
The presynaptic storage and release of glutamate, an excitatory neurotransmitter, is modulated by a family of transport proteins known as vesicular glutamate transporters. Vesicular glutamate transporter 1 (VGLUT1) is widely distributed in the central nervous system of most mammalian and nonmammalian species, and regulates the uptake of glutamate into synaptic vesicles as well as the transport of filled glutamatergic vesicles to the terminal membrane during excitatory transmission. In rodents, VGLUT1 mRNA is primarily found in the neocortex, cerebellum, and hippocampus, and the VGLUT1 transport protein is involved in intercortical and corticothalamic projections that remain distinct from projections involving other VGLUT isoforms. With the exception of a few thalamic sensory nuclei, VGLUT1 mRNA is absent from subcortical areas and does not colocalize with other VGLUT mRNAs. VGLUT1 is similarly restricted to a few thalamic association nuclei and does not colocalize with other VGLUT proteins. However, recent work in primates has shown that VGLUT1 mRNA is also found in several subcortical nuclei as well as cortical areas, and that VGLUT1 may overlap with other VGLUT isoforms in glutamatergic projections. In order to expand current knowledge of VGLUT1 distributions in primates and gain insight on glutamatergic transmission in the visual system of primate species, we examined VGLUT1 mRNA and protein distributions in the lateral geniculate nucleus, pulvinar complex, superior colliculus, V1, V2, and the middle temporal area (MT) of prosimian galagos. We found that, similar to other studies in primates, VGLUT1 mRNA and protein are widely distributed in both subcortical and cortical areas. However, glutamatergic projections involving VGLUT1 are largely limited to intrinsic connections within subcortical and cortical areas, as well as the expected intercortical and corticothalamic projections. Additionally, VGLUT1 expression in galagos allowed us to identify laminar subdivisions of the superior colliculus, V1, V2, and MT.
兴奋性神经递质谷氨酸的突触前储存和释放受一类称为囊泡谷氨酸转运体的转运蛋白家族调控。囊泡谷氨酸转运体1（VGLUT1）广泛分布于大多数哺乳动物和非哺乳动物物种的中枢神经系统，在兴奋性传递过程中调节谷氨酸摄取到突触小泡以及将充满谷氨酸的囊泡运输到终末膜。在啮齿动物中，VGLUT1 mRNA主要存在于新皮层、小脑和海马体，VGLUT1转运蛋白参与皮层间和皮质丘脑投射，这些投射与涉及其他VGLUT亚型的投射不同。除少数丘脑感觉核外，皮层下区域不存在VGLUT1 mRNA，且不与其他VGLUT mRNA共定位。VGLUT1同样局限于少数丘脑联合核，不与其他VGLUT蛋白共定位。然而，最近在灵长类动物中的研究表明，VGLUT1 mRNA也存在于几个皮层下核以及皮层区域，并且VGLUT1可能在谷氨酸能投射中与其他VGLUT亚型重叠。为了扩展当前对灵长类动物中VGLUT1分布的认识，并深入了解灵长类动物视觉系统中的谷氨酸能传递，我们研究了原猴类夜猴外侧膝状体核、丘脑枕复合体、上丘、V1、V2和颞中区（MT）中VGLUT1 mRNA和蛋白的分布。我们发现，与灵长类动物的其他研究相似，VGLUT1 mRNA和蛋白广泛分布于皮层下和皮层区域。然而，涉及VGLUT1的谷氨酸能投射在很大程度上仅限于皮层下和皮层区域内的内在连接，以及预期的皮层间和皮质丘脑投射。此外，夜猴中VGLUT1的表达使我们能够识别上丘、V1、V2和MT中的层状细分。
