[Effects of triiodothyronine on the learning and memory behaviors in neonatal mice following excitotoxic brain damage].
OBJECTIVE
Some research has shown that learning and memory function impairments in rats with hypothyroidism are associated with triiodothyronine (T3) deficiency in neurons. This study aimed to investigate the effects of L-T3 administration on learning and memory behaviors in neonatal mice with excitotoxic brain damage.


METHODS
Seventy-one 5-day-old ICR neonatal mice were randomly assigned to five groups: controls that received intracerebral and intraperitoneal injections of phosphate buffered saline (PBS) (n=14); a group that received intracerebral injections of ibotenic acid (IA) and intraperitoneal injection of PBS (n=14); 3 groups that received intracerebral injections of IA and intraperitoneal injection of L-T3 at 0.2, 0.5, and 1 microg/kg, respectively (n=14-15). Intraperitoneal injections were done 1, 24, 48, 72 and 96 hrs after intracerebral injections. Learning and memory functions were evaluated by the Y-maze discrimination learning test on postnatal days 33-34.


RESULTS
The learning and memory functions in the highest L-T3 dose group were significantly better than those in the IA, and the lower L-T3 dose groups, presenting with decreased number of trials to criterion[15.8 + or - 4.5 vs 21.3 + or - 6.3 (IA group), 20.5 + or - 6.0 (0.2 microg/kg L-T3 group) or 21.0 + or - 6.5 (0.5 microg/kg L-T3 group); P<0.05], and achieving a higher correct percentage [91.4+ or - 9.5% vs 79.3 + or - 10.0% (IA group), 77.9 + or - 14.2% (0.2 microg/kg L-T3 group) or 80.7 + or - 12.2% (0.5 microg/kg L-T3 group); P<0.05].


CONCLUSIONS
High-dose L-T3 (1 microg/kg) may improve learning and memory functions in mice following excitotoxic brain damage.
Wu
Gen-Feng
GF
Department of Pediatrics, First Affiliated Hospital of Kunming Medical College, Kunming 650032, China.
He
Xiang-Ying
XY
Li
Qi
Q
Xu
Jing
J
Xiao
Qun-Wen
QW
Qi
Zhi-Ye
ZY
Liang
Kun
K
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000187:drug effects*; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D005260:Female; D007051:Ibotenic Acid / Q000633:toxicity*; D007858:Learning / Q000187:drug effects*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D014284:Triiodothyronine / Q000494:pharmacology*
D018690:Excitatory Amino Acid Agonists; D014284:Triiodothyronine; D007051:Ibotenic Acid