Synapse-to-neuron ratio in the lateral geniculate nucleus of rats exposed chronically to ethanol.
Effects of chronic ethanol exposure on synapse-to-neuron ratio in the rat lateral geniculate nucleus were investigated. Male Sprague-Dawley rats were exposed to ethanol, using the Lieber-DeCarli liquid diets, for 4 months starting at the age of 5 weeks. Brains were perfusion-fixed, and the region containing the dorsal lateral geniculate nucleus was cut into slabs (500 microns thick) that were epoxy resin-embedded. From each rat, three slabs containing the structure were serially sectioned for electron microscopy. Using the double disector method, the study shows an unaltered synapse-to-neuron ratio in ethanol-treated rats when compared with controls. The findings are in agreement with previous studies on the visual system using the same exposure model. In contrast, a previous study has shown that the synapse-to-neuron ratio in locus ceruleus of ethanol-treated rats is reduced by 50%. Other studies have shown that, whereas the glutamatergic NMDA receptor is very sensitive to ethanol, the kainate/AMPA type of receptor is very much less so. Thus, the difference in ethanol-induced synapse elimination between the two regions may reflect this different sensitivity of the glutamatergic receptors, which are of the kainate/AMPA type in the lateral geniculate nucleus and of the NMDA type in the locus ceruleus.
Kjellström
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Department of Pathology, Sahlgren University Hospital, Göteborg, Sweden.
Conradi
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D000437:Alcoholism / Q000473:pathology*; D000818:Animals; D000431:Ethanol / Q000633:toxicity; D005829:Geniculate Bodies / Q000187:drug effects / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D009410:Nerve Degeneration / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000187:drug effects; D012016:Reference Values; D013569:Synapses / Q000187:drug effects / Q000473:pathology*; D014795:Visual Pathways / Q000187:drug effects / Q000473:pathology
D017470:Receptors, Glutamate; D000431:Ethanol