Pawluski J L, Galea L A M
Program in Neuroscience, Department of Psychology and Brain Research Centre, University of British Columbia, 2136 West Mall, Vancouver, BC, Canada V6T 1Z4.
Neuroscience. 2007 Oct 12;149(1):53-67. doi: 10.1016/j.neuroscience.2007.07.031. Epub 2007 Jul 25.
Pregnancy and the postpartum period are a time of maximal neural and behavioral plasticity. Recent work has shown that hippocampus-dependent learning and memory performance and hippocampus morphology are affected by motherhood and reproductive experience (number of times pregnant and given birth). Adult neurogenesis in the dentate gyrus of the hippocampus is influenced by steroid hormones such as estradiol and corticosterone, which fluctuate during pregnancy and the postpartum period. Thus, it is possible that hippocampal neurogenesis may be affected by motherhood and reproductive experience. The present study aimed to investigate the role of reproductive experience on hippocampal neurogenesis via cell proliferation and cell survival and to determine whether differences were due to the effect of pregnancy and/or pup-exposure alone. Four groups of female Sprague-Dawley rats were used; multiparous, primiparous, nulliparous, and nulliparous rats exposed to pups. All rats were injected with 5-bromo-2-deoxyuridine (BrdU) (200 mg/kg) approximately 24 h after birth/pup-exposure with age-matched controls. Rats were perfused either 24 h (Expt. 1: Cell proliferation) or 21 days (Expt. 2: Cell survival) after BrdU injection. Results show there is a significant decrease in cell proliferation in the dentate gyrus of primiparous and multiparous rats during the early postpartum period, and a decrease in cell survival in the dentate gyrus during the postpartum in primiparous rats, regardless of pup-exposure, compared with all other groups. In addition, brief pup exposure to nulliparous rats significantly increased cell proliferation and cell death in the dentate gyrus, while 22 days of pup exposure to nulliparous rats (sensitized rats) resulted in increased cell survival and cell death in the dentate gyrus. Collectively these results indicate that reproductive experience significantly affects hippocampal neurogenesis and that these effects are not due to the effect of pregnancy or pup-exposure alone.
怀孕和产后时期是神经和行为可塑性最强的时期。最近的研究表明，依赖海马体的学习和记忆能力以及海马体形态会受到母亲身份和生殖经历（怀孕和分娩次数）的影响。海马体齿状回中的成年神经发生受到雌二醇和皮质酮等类固醇激素的影响，这些激素在怀孕和产后时期会发生波动。因此，海马体神经发生可能会受到母亲身份和生殖经历的影响。本研究旨在通过细胞增殖和细胞存活来探究生殖经历对海马体神经发生的作用，并确定差异是否仅由怀孕和/或接触幼崽的影响所致。使用了四组雌性斯普拉-道利大鼠；经产大鼠、初产大鼠、未生育大鼠以及接触幼崽的未生育大鼠。所有大鼠在出生/接触幼崽后约24小时与年龄匹配的对照组一起注射5-溴-2'-脱氧尿苷（BrdU）（200毫克/千克）。在注射BrdU后24小时（实验1：细胞增殖）或21天（实验2：细胞存活）对大鼠进行灌注。结果显示，与所有其他组相比，初产和经产大鼠在产后早期齿状回中的细胞增殖显著减少，并且初产大鼠在产后期间齿状回中的细胞存活减少，无论是否接触幼崽。此外，未生育大鼠短暂接触幼崽会显著增加齿状回中的细胞增殖和细胞死亡，而未生育大鼠接触幼崽22天（致敏大鼠）会导致齿状回中的细胞存活和细胞死亡增加。这些结果共同表明，生殖经历会显著影响海马体神经发生，并且这些影响并非仅由怀孕或接触幼崽的影响所致。
