Effects of an acute treatment with L-thyroxine on memory, habituation, danger avoidance, and on Na+, K+ -ATPase activity in rat brain.
Thyroid hormones (THs) have a relevant action on brain development and maintenance. By using an acute treatment to induce a hyperthyroid animal model, we aimed at investigating the effect of an altered THs levels on learning and memory and on the activity of Na(+), K(+)-ATPase in the rat brain. Our results have shown that the acute treatment with L-T4 did not alter the retrieval of the inhibitory avoidance task, but had a significant effect on the elevated plus maze and on open-field performance in rats. We suggest that animals subjected to L-T4 administration improved the habituation to a novel environment as well as a better evaluation of a dangerous environment, respectively. Na(+), K(+)-ATPase activity is increased in parietal cortex (30%), but it is not altered in hippocampus in L-T4 treated group. These both brain structures are involved in memory processing and it was previously demonstrated that there is a double dissociation between them for spatial location information, perceptual and episodic memory. We propose the hypothesis that this increase of Na(+), K(+)-ATPase activity in parietal cortex may be correlated to our results in behavior tests, which suggest a role of THs as well as of the Na(+), K(+)-ATPase in the cognitive process.
Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. reis.lunardelli@gmail.com
Eleonora Araújo
EA
dos Reis-Lunardelli
Maria Rosana
MR
Ramirez
Cibele Canal
CC
Castro
Adriana Simon
AS
Coitinho
Caren
C
Bavaresco
Laura Schumacher Schuh
LS
da Trindade
Myriam Fortes
MF
Perrenoud
Angela Terezinha de Souza
AT
Wyse
João José Freitas
JJ
Sarkis
Iván
I
Izquierdo
D000818:Animals; D001007:Anxiety / Q000523:psychology; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D006185:Habituation, Psychophysiologic / Q000187:drug effects*; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008568:Memory / Q000187:drug effects*; D009043:Motor Activity / Q000187:drug effects; D010296:Parietal Lobe / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D012309:Risk-Taking; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013570:Synaptic Membranes / Q000187:drug effects / Q000201:enzymology; D013963:Thyroid Hormones / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology*
D013963:Thyroid Hormones; D000254:Sodium-Potassium-Exchanging ATPase; D013974:Thyroxine