Kinsley Craig H, Trainer Regina, Stafisso-Sandoz Graciela, Quadros Princy, Marcus Lori Keyser, Hearon Christa, Meyer Elizabeth Ann Amory, Hester Naomi, Morgan Melissa, Kozub Frederick J, Lambert Kelly G
Department of Psychology-Center for Neuroscience, 103 Richmond Hall, University of Richmond, VA 23173, USA.
Horm Behav. 2006 Feb;49(2):131-42. doi: 10.1016/j.yhbeh.2005.05.017. Epub 2005 Jul 6.
Short-term fluctuations in steroid hormones such as estradiol (E2) and progesterone (P) can affect the concentration of hippocampal dendritic spines in adult, cycling nulliparous female rats. Pregnancy is characterized by a significantly longer duration of substantially elevated E2 and P compared to the estrous cycle. Thus, even greater changes than those reported during estrus may be evident. In two experiments, we examined the extent to which reproductive and hormonal state altered the concentration of apical neuronal dendritic spines of the CA1 region of the hippocampus in the following age-matched groups (N's = 7-10/group) of rats: in Exp. 1., CA1 dendritic spine density was examined in nulliparous diestrus (DES), proestrus (PRO), and estrus (ES) females, and late-pregnant (LP) (day 21) and lactating (day 5-6; LACT) females. In Exp. 2, the effects on spine density of a regimen mimicking pregnancy (and that stimulates maternal behavior) were examined, using ovariectomized, no hormone-exposed (OVX-minus) vs. sequential P&E(2)-treated (OVX + P&E2) groups. For both experiments, brains were removed, Golgi-Cox-stained and the most lateral tertiary branches of the apical dendrite of completely-stained hippocampal CA1 pyramidal neurons were traced with oil-immersion at x 1600 and dendritic spine density (# spines/10 micro dendritic segment) recorded. In Exp. 1, spine density was increased in LP and LACT females (which were not different) compared to the other virgin groups, including PRO females, who had more spines than DES and ES. In Exp. 2, OVX + P&E2 displayed significantly more dendritic spines per 10 micro than OVX-minus females (and had numbers that were similar to those of LP and LACT from Exp. 1). Pregnancy and its attendant hormonal fluctuations, therefore, may alter hippocampal neurons that regulate some non-pup-directed components of maternal behavior (e.g., nest building) or behaviors that support maternal behavior (e.g., foraging, associative memory).
雌二醇（E2）和孕酮（P）等甾体激素的短期波动会影响成年未孕雌性大鼠海马树突棘的浓度。与发情周期相比，怀孕的特点是E2和P显著升高的持续时间更长。因此，可能会出现比发情期报告的更大变化。在两项实验中，我们研究了生殖和激素状态在以下年龄匹配的大鼠组（每组N = 7 - 10）中改变海马CA1区顶端神经元树突棘浓度的程度：在实验1中，检测了未孕动情后期（DES）、动情前期（PRO）、发情期（ES）雌性大鼠以及妊娠后期（LP）（第21天）和哺乳期（第5 - 6天；LACT）雌性大鼠的CA1树突棘密度。在实验2中，使用去卵巢、未接触激素（OVX - ）与序贯给予P和E2处理（OVX + P&E2）的组，研究了模拟怀孕（并刺激母性行为）方案对树突棘密度的影响。对于这两项实验，取出大脑，进行高尔基-考克斯染色，并用油镜在x 1600下追踪完全染色的海马CA1锥体神经元顶端树突的最外侧三级分支，并记录树突棘密度（每10微米树突段的棘突数）。在实验1中，与其他未孕组相比，LP和LACT雌性大鼠（两者无差异）的棘突密度增加，包括PRO雌性大鼠，其棘突比DES和ES雌性大鼠更多。在实验2中，OVX + P&E2组每10微米显示的树突棘明显多于OVX - 组（其数量与实验1中的LP和LACT组相似）。因此，怀孕及其伴随的激素波动可能会改变调节母性行为的一些非针对幼崽的组成部分（例如筑巢）或支持母性行为的行为（例如觅食、联想记忆）的海马神经元。
