Glutamate and aspartate immunoreactivity in hypothalamic presynaptic axons

作者：AN van den Pol · 发表于：Journal of Neuroscience · 年份：1991 · DOI：10.1523/jneurosci.11-07-02087.1991 · 被引用次数：253 · 研究领域：Neuroscience and Neuropharmacology Research、Neurogenesis and neuroplasticity mechanisms、Sleep and Wakefulness Research

Within the hypothalamus, a large number of neuroactive substances are found, many first detected in this part of the brain. Excitatory amino acids, recognized as important transmitters in other parts of the brain, have received little attention here. To study glutamate immunoreactivity at the ultrastructural level in the hypothalamus, postembedding colloidal gold or silver-intensified gold was used. Antisera raised against glutamate conjugated with glutaraldehyde to keyhole limpet hemocyanin were specific for glutamate, tested with a battery of tests including immunodot blot, ELISA assays. Western blot, and Sepharose epoxy-conjugated amino acids. Antisera did not cross-react with other amino acids and related compounds, with proteins containing glutamate, or with polyglutamate. A population of presynaptic boutons in the suprachiasmatic, arcuate, ventromedial, supraoptic, and parvocellular and magnocellular paraventricular nuclei showed strong immunoreactivity for glutamate. Highly labeled presynaptic axons generally made asymmetrical Gray type 1 synaptic contacts with dendrites or cell bodies and had up to eight times more immunogold particles per unit area than postsynaptic dendrites. Axon terminals exhibiting strong glutamate immunoreactivity had large numbers of round, clear vesicles adjacent to the synaptic specialization together with a few larger, dense-core vesicles. The largest number of gold particles over axons were located in regions containing the small clear vesi...