title: Postnatal apoptosis, development, and sex difference in the lateral septum of rats.
abstract: To determine whether apoptosis is involved in the formation of the structure and morphological sex difference of the lateral septum (LS), the postnatal developmental changes in the number of apoptotic cells were examined in the LS on postnatal day 1 (PD1 = birth day), 4, 6, 8, 11, 16, and 31 in male and female rats. Apoptotic cells were immunohistochemically detected by antibody against single-stranded DNA (ssDNA) or active caspase-3. The volume of the LS was also measured and was found to increase with age. The number of apoptotic cells detected by anti-ssDNA in the LS increased from PD1 to PD8 but decreased after PD11. Also, the LS was divided into dorsal, intermediate, and ventral parts (LSd, LSi, and LSv), and the volume and number of ssDNA-immunoreactive cells in each part were measured on PD6, 8, 11, 16, and 31. In both sexes, a large number of ssDNA-immunoreactive cells was found in the LSd and LSi on PD8 (but not on PD6) and in the LSv on PD6 and PD8. On PD6, the number of active caspase-3-immunoreactive cells was significantly greater in the LSv than in the LSd or LSi, in both sexes. Only the LSi of males had a high number of ssDNA-immunoreacitve cells on PD16; the number was significantly greater than that of females of the same age. However, there was no significant sex difference in the number of active caspase-3-immunoreacitve cells in the LSi on PD16. On PD31, the volume of the LSi was significantly greater in females than in males. There was no sex difference in volume or number of apoptotic cells in the LSd or LSv. These findings indicate that loss of cells due to apoptosis, which is partially caused by activation of caspase-3, occurs in the LS during postnatal development, with regional differences. They also indicate that sex difference in caspase-3-independent apoptosis contributes to morphological sexual differentiation of the LSi.
authors.affiliation: Graduate School of Science and Technology, Kobe University, Nada-ku, Kobe 657-8501, Japan. stsuka@kobe-u.ac.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Tsukahara
authors.forename: Kouichi
authors.initials: K
authors.lastname: Inami
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Maekawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Kakeyama
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Midori
authors.initials: M
authors.lastname: Yuji
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kannan
authors.forename: Korehito
authors.initials: K
authors.lastname: Yamanouchi
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D048429:Cell Size; D004277:DNA, Single-Stranded / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012686:Septal Nuclei / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D020665:Septum of Brain / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D012727:Sex Characteristics; D012733:Sex Differentiation / Q000235:genetics; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases