Abstract | OBJECTIVE: STUDY DESIGN: Four hours after the injection of LPS (1 mg/kg, i.p.), 7-day-old Wistar rat pups were subjected to unilateral HI for 1 hour according to Levine's procedure. Injections of 0.5 mg/kg of dexamethasone (DEX-treated group, n = 15) or saline (saline-treated group, n = 15) were given 4 hours before HI. A sham-operated control group received neither LPS nor HI (n = 15). We chose rats of this age because their stage of brain maturation is similar to the human neonate. Over the 7 to 16 weeks after treatment, a choice reaction time (CRT) task was used for assessment of attention processes in each group, an 8-arm radial maze task was used to test short-term memory, and a water maze task was used to test long-term memory. In the CRT task, the reward food was released when the tested animal correctly pressed a lever on the side of an illuminating lamp. The correct and incorrect lever pressings were counted. In the 8-arm radial maze task, rats were allowed to move freely, seeking a reward of food placed at the end of 1 arm. An error was defined as the choice of an arm that had already been visited. In the water maze, rats had to swim to seek a concealed platform as aversive escape motivation. At 19 weeks, the rats were euthanized, the brain was removed, sectioned coronally, and the volume of each part was measured. RESULTS: The striatum, cortex, and hippocampus showed reductions in volume in the saline-treated group (42.7%, 49.2%, and 34.9% decreases compared with the sham-operated controls, respectively), but this was not observed in the DEX-treated group. All learning and memory processes were impaired with the combination of LPS and HI treatment, but these deficits were almost completely prevented by DEX treatment. CONCLUSION:
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Authors | Tomoaki Ikeda, Kenichi Mishima, Naoya Aoo, An Xin Liu, Nobuaki Egashira, Katsunori Iwasaki, Michihiro Fujiwara, Tsuyomu Ikenoue |
Journal | American journal of obstetrics and gynecology
(Am J Obstet Gynecol)
Vol. 192
Issue 3
Pg. 719-26
(Mar 2005)
ISSN: 0002-9378 [Print] United States |
PMID | 15746663
(Publication Type: Journal Article)
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Chemical References |
- Anti-Inflammatory Agents
- Lipopolysaccharides
- Dexamethasone
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Topics |
- Animals
- Animals, Newborn
- Anti-Inflammatory Agents
(administration & dosage, therapeutic use)
- Brain
(pathology)
- Brain Damage, Chronic
(chemically induced, complications)
- Choice Behavior
(drug effects)
- Dexamethasone
(administration & dosage, therapeutic use)
- Disease Models, Animal
- Hypoxia-Ischemia, Brain
(complications)
- Learning Disabilities
(etiology, pathology, prevention & control)
- Lipopolysaccharides
- Maze Learning
(drug effects)
- Memory
(drug effects)
- Memory, Short-Term
(drug effects)
- Rats
- Rats, Wistar
- Reaction Time
(drug effects)
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