Improved learning in microencephalic rats

Shuichi Ueda*, Kanji Yoshimoto, Taro Kadowaki, Koichi Hirata, Shin Ichi Sakakibara

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Environmental enrichment (EE) facilitates recovery from behavioral abnormalities and spatial memory disabilities in several neurological disease models. Exposure to EE improves spatial memory acquisition and enhances the survival of newly generated cells in the dentate gyri of adult rodents. However, the effects of EE on spatial learning and neurogenesis in the methylazoxymethanol acetate-induced microencephalic rat have not been investigated. Depletion of serotonin in the rat hippocampus is known to influence spatial memory and adult neurogenesis, suggesting a role for serotonin in these processes. To confirm this hypothesis, male methylazoxymethanol acetate-induced microencephalic rats were exposed to EE or conventional housing after weaning; half of these rats further received intracisternal 5,7-dihydroxytryptamine on postnatal day 3, to induce long-lasting depletion of serotonin. As adults, these microencephalic rats were observed using the Morris water maze test and examined for hippocampal neurogenesis. EE alleviated the impairment of spatial memory acquisition and enhanced neurogenesis in the dentate gyri of adult microencephalic rats. Injection of 5,7-dihydroxytryptamine during the neonatal period caused pronounced reductions in hippocampal serotonin levels in these rats. Long-lasting depletion of serotonin eliminated the EE-induced alleviation of spatial memory acquisition and neurogenesis impairment in microencephalic rats. The present results suggest that EE alleviates spatial memory performance deficits in microencephalic rats and further indicate that serotonin might be involved in the underlying mechanisms through increased hippocampal neurogenesis. These data provide new insights into therapeutic interventions for individuals with human migration disorders associated with learning disabilities.

Original languageEnglish
Pages (from-to)58-63
Number of pages6
JournalCongenital Anomalies
Issue number1
Publication statusPublished - 2010 Mar
Externally publishedYes


  • Dentate gyrus
  • Microencephaly
  • Neurogenesis
  • Serotonin
  • Water maze

ASJC Scopus subject areas

  • General Medicine


Dive into the research topics of 'Improved learning in microencephalic rats'. Together they form a unique fingerprint.

Cite this