Chronic corticosterone impairs inhibitory avoidance in rats: possible link with atrophy of hippocampal CA3 neurons.
The aim of our work was to evaluate the effect of a chronic (22 days) administration of corticosterone, which induces supraphysiological serum levels of the hormone, on an inhibitory avoidance learning in rats (one-trial step-through learning task, footshock: 0.5 mA, 2 s). We also studied hippocampal markers of neuroanatomical CA3 pyramidal neuron atrophy by using the Golgi staining method. Chronic exposure to high CORT serum levels induced a significant impairment of inhibitory avoidance learning. The CORT group also showed hippocampal glucocorticoid receptor (GR) downregulation and the decrease of hippocampal CA3 branch points and total dendritic length in the apical tree that would be causally related with the learning impairment.
Bisagno
V
V
Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, piso 15 (1113), Capital Federal, Argentina.
Ferrini
M
M
Ríos
H
H
Zieher
L M
LM
Wikinski
S I
SI
D000311:Adrenal Glands / Q000187:drug effects / Q000473:pathology; D000818:Animals; D001284:Atrophy; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology*; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000008:administration & dosage / Q000097:blood / Q000633:toxicity*; D003600:Cytosol / Q000378:metabolism; D003712:Dendrites / Q000187:drug effects / Q000473:pathology; D003907:Dexamethasone / Q000378:metabolism; D004343:Drug Implants; D066298:In Vitro Techniques; D008297:Male; D009929:Organ Size / Q000187:drug effects; D017966:Pyramidal Cells / Q000187:drug effects* / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000378:metabolism
D004343:Drug Implants; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone; D003345:Corticosterone