Pregnancy is a complex process, involving a number of hormones and trophic factors, many of which are formed in the placenta. Several of these trophic factors have an effect at the neuronal level, such as BDNF. Consequently, recent reports have shown that exposure to these hormones (estrogen and progesterone) and trophic factors such as BDNF exert a neuroprotective effect. Here, we study the effect of the number of pregnancies on dendritic morphology of aged female rats (18 months of age). Rats of the 18-month-old Sprague Dawley strain with zero, one, two, and three gestations were evaluated for locomotor activity, and Golgi-Cox stain was performed to evaluate the dendritic morphology parameters, the number of dendritic spines, total dendritic length, and branching order number. Adult nulliparous rats (3 months of age) were used as another control group. Adult nulliparous and aging rats with two pregnancies showed an increase in locomotor activity. Adult nulliparous showed an increase in the dendritic spine number compared to old nulliparous rats in both layers of the PFC, the DG, and NAcc. Old rats with two and three pregnancies also showed an increase in the number of dendritic spines compared to old nulliparous rats in layers 3 and 5 of the PFC and in the CA1. Aging animals with one pregnancy also showed an increase in dendritic length compared to old nulliparous rats in the CA1. Our results clearly suggest that two and three pregnancies increase the dendritic spines number in the PFC and CA1 of aged female rats.

中文翻译：

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怀孕会改变老年大鼠皮质和皮质下缘脑区的脊柱数目。

怀孕是一个复杂的过程，涉及许多激素和营养因子，其中许多是在胎盘中形成的。这些营养因子中的几种在神经元水平上有作用，例如BDNF。因此，最近的报道表明，暴露于这些激素（雌激素和孕酮）和营养因子（如BDNF）具有神经保护作用。在这里，我们研究了怀孕次数对老年雌鼠（18个月大）树突形态的影响。对18个月大的Sprague Dawley应变分别为零，一，二和三个妊娠的大鼠进行运动活动评估，并进行Golgi-Cox染色以评估树突形态参数，树突棘数量，总树突长度以及分支订单号。将成年未产大鼠（3个月大）用作另一个对照组。两次怀孕的成年未成年和衰老大鼠显示运动能力增加。在PFC，DG和NAcc的两层中，成年未成年大鼠的树突棘数目均比旧的未成年大鼠有所增加。在PFC的第3层和第5层以及在CA1中，有两胎和三胎的老大鼠的树突棘数量也比未产卵的老大鼠增加。与CA1中的未产卵老鼠相比，一次怀孕的衰老动物的树突长度也增加了。我们的结果清楚地表明，两次和三个怀孕会增加老年雌性大鼠的PFC和CA1中的树突棘数量。在PFC，DG和NAcc的两层中，成年未产鼠的树突棘数目均比旧未产鼠的树突增加。在PFC的第3层和第5层以及在CA1中，有两胎和三胎的老大鼠的树突棘数量也比未产卵的老大鼠增加。与CA1中的未产卵老鼠相比，一次怀孕的衰老动物的树突长度也增加了。我们的结果清楚地表明，两次和三个怀孕会增加老年雌性大鼠的PFC和CA1中的树突棘数量。在PFC，DG和NAcc的两层中，成年未成年大鼠的树突棘数目均比旧的未成年大鼠有所增加。在PFC的第3层和第5层以及在CA1中，有两胎和三胎的老大鼠的树突棘数量也比未产卵的老大鼠增加。与CA1中的未产卵老鼠相比，一次怀孕的衰老动物的树突长度也增加了。我们的结果清楚地表明，两次和三个怀孕会增加老年雌性大鼠的PFC和CA1中的树突棘数量。在PFC的第3层和第5层以及在CA1中，有两胎和三胎的老大鼠的树突棘数量也比未产卵的老大鼠增加。与CA1中的未产卵老鼠相比，一次怀孕的衰老动物的树突长度也增加了。我们的结果清楚地表明，两次和三个怀孕会增加老年雌性大鼠的PFC和CA1中的树突棘数量。在PFC的第3层和第5层以及在CA1中，有两胎和三胎的老大鼠的树突棘数量也比未产卵的老大鼠增加。与CA1中的未产卵老鼠相比，一次怀孕的衰老动物的树突长度也增加了。我们的结果清楚地表明，两次和三个怀孕会增加老年雌性大鼠的PFC和CA1中的树突棘数量。