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Anatomical Science International

, Volume 89, Issue 4, pp 199–206 | Cite as

Postnatal changes in the number of serotonin-immunoreactive cells in midbrain raphe nuclei of male rats

  • Hiroyuki Ito
  • Tetsuji Moriizumi
  • Yuji Shimogawa
  • Korehito YamanouchiEmail author
Original Article
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Abstract

To clarify the developmental changes in serotonergic neurons in the subdivisions of the dorsal (DR) and median raphe (MR) nuclei before puberty, the extent of the nuclei and the number of serotonin (5-HT) immunoreactive (ir) cells were measured in 5-, 15-, and 30-day-old rats and 8-week-old (adult) castrated male rats. The brains were fixed and 50 μm frozen sections prepared. After immunostaining for 5-HT, the number of 5-HT-ir cells in a 0.2 × 0.2 mm frame in the dorsal, ventral and lateral subdivisions of the DR (dDR, vDR and lDR, respectively) and MR were counted. Total numbers of 5-HT-ir cells counted in the frame of three sections in each rat were expressed as the number of cells per cubic millimeter (density). The results indicated that the densities of 5-HT-ir cells in the MR were almost the same in all age groups. On the other hand, among the subdivisions of the DR, the mean density of 5-HT-ir cells in 15-day-old rats was higher than that in the 5-day-old group in the lDR only. The area of the three sections of the DR and of the MR was also measured. The area of the DR in 15-day-old rats was found to be twice that in the 5-day-old rats, and differed from the area in 30-day-old rats and adults. There were no differences among the age groups in the areas of the MR. The results indicate that the expression of 5-HT in the lDR and extent of the DR increased to adult levels from days 5 to 15 after birth. In the dDR, vDR and MR, expression of 5-HT at postnatal day 5 was at adult levels already.

Keywords

Dorsal and median raphe nuclei 5-HT immunopositive cell Postnatal development Male rat 

Notes

Acknowledgment

This study was supported by Grants-in-Aid for scientific research from the MEXT of Japan; Kibankeisei (2010).

Conflict of interest

None.

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Copyright information

© Japanese Association of Anatomists 2013

Authors and Affiliations

  • Hiroyuki Ito
    • 1
    • 2
  • Tetsuji Moriizumi
    • 1
  • Yuji Shimogawa
    • 2
  • Korehito Yamanouchi
    • 2
    Email author
  1. 1.Department of AnatomyShinshu University School of MedicineNaganoJapan
  2. 2.Laboratory of Neuroendocrinology, Department of Human Behavior and Environment Sciences, School of Human SciencesWaseda UniversityTokorozawaJapan

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