Multifaceted alterations of the thalamo-cortico-thalamic loop in adult rats prenatally exposed to ethanol.
The thalamo-cortico-thalamic loop was investigated in adult rats exposed to ethanol during the last week of fetal life. Animals underwent either cortical or thalamic injections of lectin-conjugated horseradish peroxidase. Results demonstrate that prenatal exposure to ethanol causes permanent changes in the thalamocortical circuits. Alterations of thalamo-cortical and cortico-thalamic projections are concentrated at the level of axon terminal fields. The most severe thalamic damage is observed in the anterior intralaminar and midline nuclei; crossed cortico-thalamic projections also appear to be severely impaired. In the cortex, the damage to thalamic terminals displays a medio-lateral gradient of increasing severity through sensori-motor areas, with the lateral fields more impaired. Cells of origin of thalamo-cortical and cortico-thalamic projections are less affected by prenatal ethanol exposure: in the thalamus and layer 5 of sensori-motor cortex labeled cells exhibit normal values of areal numeric density. Conversely, cortico-thalamic neurons of layer 6, especially in the lateral agranular sensori-motor field, display smaller values of areal density than those of normal animals. Possible mechanisms underlying the establishment of these abnormalities are discussed.
Granato
A
A
Institute of Anatomy, Catholic University, Rome, Italy.
Santarelli
M
M
Sbriccoli
A
A
Minciacchi
D
D
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000473:pathology*; D004195:Disease Models, Animal; D000431:Ethanol / Q000633:toxicity; D005260:Female; D063647:Fetal Alcohol Spectrum Disorders / Q000473:pathology*; D009434:Neural Pathways / Q000187:drug effects / Q000473:pathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D017729:Presynaptic Terminals / Q000187:drug effects / Q000473:pathology; D051381:Rats; D013788:Thalamus / Q000187:drug effects / Q000473:pathology*
D000431:Ethanol