Center for Neural Science, New York University, New York, New York, USA.
Hippocampus. 2021 Feb;31(2):170-188. doi: 10.1002/hipo.23275. Epub 2020 Nov 4.
The hippocampus carries out multiple functions: spatial cognition dorsally (DH) and regulation of emotionality-driven behavior ventrally (VH). Previously, we showed that dendrites of DH and VH pyramidal neurons of female rats are still developing robustly during adolescence and are altered by the experience of food restriction and voluntary exercise on a wheel. We tested whether such anatomical changes during adolescence impact anxiety-like behavior and spatial cognition. Four groups of female rats were evaluated for these behaviors: those with wheel access in its cage from postnatal day (P) 36-44 (EX); those with food access restricted to 1 hr per day, from P40 to 44 (FR); those with EX from P36 to 44, combined with FR from P40 to 44, which we will refer to as EX + FR; and controls, CON (no EX, no FR). Open field test for anxiety-like behavior and active place avoidance test for spatial cognition were conducted at P47-49, the age when food restricted animals have restored body weight, or at P54-56, to identify more enduring effects. Anxiety-like behavior was elevated for the EX and FR groups at P47-49 but not for the EX + FR group. By P54-56, the EX + FR and EX groups exhibited less anxiety-like behavior, indicating a beneficial delayed main effect of exercise. There was a beneficial main effect of food restriction upon cognition, as the FR group showed cognition superior to CONs' at P44-46 and P54-56, while the EX + FR animals also showed enhanced spatial learning at P54-56. EX + FR animals with best adaptation to the feeding schedule showed the best spatial learning performance but with a delay. The EX group exhibited only a transient improvement. These findings indicate that FR, EX, and EX + FR in mid-adolescence are all beneficial in reducing anxiety-like behavior and improving spatial cognition but with subtle differences in the timing of their manifestation, possibly reflecting the protracted maturation of the hippocampus.
背侧（DH）进行空间认知，腹侧（VH）调节情绪驱动的行为。此前，我们发现雌性大鼠 DH 和 VH 锥体神经元的树突在青春期仍在强烈发育，并受到食物限制和轮上自愿运动经验的影响。我们测试了青春期期间这种解剖结构的变化是否会影响焦虑样行为和空间认知。我们对四组雌性大鼠进行了这些行为的评估：从出生后第 36-44 天（P）开始在笼子中使用轮的（EX）组；从 P40 到 44 天每天限制食物摄入 1 小时的（FR）组；从 P36 到 44 天使用 EX，结合 P40 到 44 天 FR 的（EX+FR）组；以及对照（CON）组（无 EX，无 FR）。在 P47-49 天进行焦虑样行为的开放式场测试，在 P54-56 天进行主动回避测试，以识别更持久的影响。EX 和 FR 组在 P47-49 天表现出焦虑样行为升高，但 EX+FR 组没有。到 P54-56 天，EX+FR 和 EX 组表现出较少的焦虑样行为，表明运动具有有益的延迟主要作用。食物限制对认知有有益的主要作用，因为 FR 组在 P44-46 和 P54-56 天的认知优于 CON，而 EX+FR 动物在 P54-56 天也表现出增强的空间学习能力。适应喂养计划最好的 EX+FR 动物表现出最佳的空间学习表现，但有延迟。EX 组仅表现出短暂的改善。这些发现表明，青春期中期的 FR、EX 和 EX+FR 均有益于减少焦虑样行为和改善空间认知，但表现方式存在细微差异，这可能反映出海马体的长期成熟。
