Regeneration of 5-HT fibers in hippocampal heterotopia of methylazoxymethanol-induced micrencephalic rats after neonatal 5,7-DHT injection.
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.
Nakamura
Arata
A
Department of Neurology, Dokkyo Medical University School of Medicine, Mibu, Tochigi, Japan.
Kadowaki
Taro
T
Sakakibara
Shin-ichi
S
Yoshimoto
Kanji
K
Hirata
Koichi
K
Ueda
Shuichi
S
D015115:5,6-Dihydroxytryptamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008746:Methylazoxymethanol Acetate / Q000031:analogs & derivatives; D008831:Microcephaly / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009416:Nerve Regeneration / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D054091:Periventricular Nodular Heterotopia / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; C078441:5,7-dihydroxytryptamine creatinine; D008746:Methylazoxymethanol Acetate; D003404:Creatinine; C030667:methylazoxymethanol; D015115:5,6-Dihydroxytryptamine