Regeneration of 5-HT fibers in hippocampal heterotopia of methylazoxymethanol-induced micrencephalic rats after neonatal 5,7-DHT injection

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

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In order to elucidate the regeneration properties of serotonergic fibers in the hippocampus of methylazoxymethanol acetate (MAM)-induced micrencephalic rats (MAM rats), we examined serotonergic regeneration in the hippocampus following neonatal intracisternal 5,7-dihydroxytryptamine (5,7-DHT) injection. Prenatal exposure to MAM resulted in the formation of hippocampal heterotopia in the dorsal hippocampus. Immunohistochemical and neurochemical analyses revealed hyperinnervation of serotonergic fibers in the hippocampus of MAM rats. After neonatal 5,7-DHT injection, most serotonergic fibers in the hippocampus of 2-week-old MAM rats had degenerated, while a small number of serotonergic fibers in the stratum lacunosum-moleculare (SLM) of the hippocampus and in the hilus adjacent to the granular cell layer of the dentate gyrus (DG) had not. Regenerating serotonergic fibers from the SLM first extended terminals into the hippocampal heterotopia, then fibers from the hilus reinnervated the DG and some fibers extended to the heterotopia. These findings suggest that the hippocampal heterotopia exerts trophic target effects for regenerating serotonergic fibers in the developmental period in micrencephalic rats.

Original languageEnglish
Pages (from-to)38-45
Number of pages8
JournalAnatomical Science International
Issue number1
Publication statusPublished - 2010 Mar 1



  • Hippocampal heterotopia
  • Methylazoxymethanol acetate
  • Micrencephalic rat
  • Regeneration
  • Serotonergic fibers

ASJC Scopus subject areas

  • Anatomy

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