Fosse V M, Heggelund P, Fonnum F
Norwegian Defence Research Establishment, Division of Environmental Toxicology, Kjeller, Norway.
J Neurosci. 1989 Feb;9(2):426-35. doi: 10.1523/JNEUROSCI.09-02-00426.1989.
We have analyzed the postnatal development of glutamatergic/aspartergic, GABAergic, and cholinergic neurotransmitter systems in the visual cortical Areas 17 and 18, lateral geniculate nucleus (LGN), pulvinar, and the visual and non-visual parts of superior colliculus (SC) in kittens. High-affinity uptake of D-aspartate (HA D-Asp), glutamate decarboxylase (GAD), and choline acetyltransferase (ChAT) activities were measured as a means of probing the development of the respective transmitter systems. HA D-Asp exceeded the adult level several-fold in all areas during the postnatal period which corresponded with the period of maximal dendritic/axonal branching patterns and synapse densities in the respective regions. GAD exhibited a gradual increase towards adult levels during the first month. The adult level was reached during postnatal week (PNW) 5-6 in Areas 17 and 18, during PNW3 within LGN, pulvinar, and the visual part of SC. In the nonvisual part of SC, the adult GAD level was reached as early as PNW2. ChAT exhibited biphasic developmental profiles in Areas 17 and 18. An initial peak of near adultlike activity in PNW2 was followed by a decline and subsequently by a slow increase towards adult levels during PNW5-17. ChAT developed very slowly in LGN and pulvinar, and in the latter structure only approximately 70% of the adult activity had been attained by PNW17. In both subdivisions of SC, ChAT had reached adult levels during PNW3-5. Dark-rearing from birth until PNW6 moderately attenuated GAD development in all areas and increased ChAT activity in Areas 17 and 18 but did not affect development of HA D-Asp in any part of the kitten visual system. Our neurochemical findings in the developing cat visual system are consistent with available evidence regarding localization of neurotransmitter systems, as well as postnatal changes in terms of cytoarchitectonics, synaptogenesis, functional development, and susceptibility to neonatal dark-rearing in visual pathways.
我们分析了小猫视皮层17区和18区、外侧膝状体核（LGN）、丘脑枕以及上丘（SC）视觉和非视觉部分中谷氨酸能/天冬氨酸能、γ-氨基丁酸能和胆碱能神经递质系统的出生后发育情况。通过测量D-天冬氨酸的高亲和力摄取（HA D-Asp）、谷氨酸脱羧酶（GAD）和胆碱乙酰转移酶（ChAT）的活性，来探究相应递质系统的发育情况。在出生后时期，所有区域的HA D-Asp都比成年水平高出几倍，这与各区域最大树突/轴突分支模式和突触密度的时期相对应。GAD在出生后的第一个月逐渐向成年水平增加。在视皮层17区和18区，出生后第5 - 6周达到成年水平；在LGN、丘脑枕和SC的视觉部分，出生后第3周达到成年水平。在SC的非视觉部分，早在出生后第2周就达到了成年GAD水平。ChAT在视皮层17区和18区呈现双相发育模式。在出生后第2周出现接近成年水平的初始峰值，随后下降，然后在出生后第5 - 17周缓慢增加至成年水平。ChAT在LGN和丘脑枕中发育非常缓慢，在丘脑枕结构中，到出生后第17周仅达到成年活性的约70%。在SC的两个亚区，ChAT在出生后第3 - 5周达到成年水平。从出生到出生后第6周进行暗饲养，适度减弱了所有区域的GAD发育，并增加了视皮层17区和18区的ChAT活性，但不影响小猫视觉系统任何部分的HA D-Asp发育。我们在发育中的猫视觉系统中的神经化学发现与关于神经递质系统定位以及视觉通路中细胞结构、突触形成、功能发育和对新生儿暗饲养易感性的产后变化的现有证据一致。
