| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4344580 | Neuroscience Letters | 2012 | 6 Pages |
Postnatal apoptosis is involved in formation of the sex difference in neuron number of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in rats. In this study, we examined the origin of neurons that die with apoptosis on the postnatal period to exhibit the sex difference in neuron number of the SDN-POA. First, we measured the number of cells that were labeled with 5-bromo-2′-deoxyuridine (BrdU) on embryonic day (ED) 17, ED18, and ED19 in the SDN-POA of rats on postnatal day (PD) 4 and PD8. The SDN-POA had many more cells labeled with BrdU on ED17 and ED18 than those on ED19. Significantly fewer cells labeled with BrdU on ED18 in the female SDN-POA from PD4 to PD8 resulted in a significant sex difference in the number at PD8. Next, combination analyses of BrdU-labeling and immunohistochemistry for single-stranded DNA (ssDNA), an apoptotic marker, were succeeded to investigate whether SDN-POA neurons generated during ED17–18 were removed by apoptosis. Many more ssDNA-immunoreactive cells that had been labeled with BrdU during ED17–18 were found in the SDN-POA of PD8 females, but few in the SDN-POA of PD8 males and PD4 females and males. These results suggest that the sex difference in the number of SDN-POA neurons generated during the late fetal period was caused by postnatal apoptosis.
► SDN-POA has many more neurons in male rats than female rats in adulthood. ► Postnatal apoptosis is involved in the sex difference in SDN-POA neuron number. ► We examined the origin of SDN-POA neurons that die with postnatal apoptosis. ► Female rats had more neurons born on ED17–18 and died with apoptosis on PD8. ► Male rats had few neurons born on ED17–18 and died with apoptosis on PD8.
