Ultrastructural morphometric analysis of GABA-immunoreactive terminals in the ventrocaudal periaqueductal grey: analysis of the relationship of GABA terminals and the GABAA receptor to periaqueductal grey-raphe magnus projection neurons

Autor: Williams, F. G., Beitz, A. J.
Zdroj: Journal of Neurocytology; October 1990, Vol. 19 Issue: 5 p686-696, 11p
Abstrakt: Summary The periaqueductal grey (PAG) plays an important role in the descending modulation of nociception. Inhibitory influences of GABAergic terminals, located within the periaqueductal grey, are thought to play a role in antinociception by influencing the activity of neurons that project to the nucleus raphe magnus and adjacent reticular nuclei. The present study utilized electron microscopic immunocytochemistry to quantitate the normal neuronal associations of GABA-immunoreactive terminals, and to visualize the neuronal distribution of the GABAA receptor in the ventrolateral periaqueductal grey of the rat. Of particular interest was a quantitative description of the interaction between GABA-immunoreactive axon terminals and periaqueductal grey neurons that were retrogradely-labelled from the nucleus raphe magnus and adjacent medullary reticular nuclei. Most terminals were observed to be immediately apposed only to two or three dendrites, although axonal and perikaryal associations were also observed. In the ventrolateral periaqueductal grey, 37.5% of all GABA-immunoreactive terminals were adjacent to periaqueductal grey-nucleus raphe magnus and periaqueductal grey-reticular nucleus projection neurons.
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