Analysis of long‐term potentiation (LTP) provides a powerful window into cellular mechanisms of learning and memory. Prior work shows late LTP (L‐LTP), lasting >3 hr, occurs abruptly at postnatal day 12 (P12) in the stratum radiatum of rat hippocampal area CA1. The goal here was to determine the developmental profile of synaptic plasticity leading to L‐LTP in the mouse hippocampus. Two mouse strains and two mutations known to affect synaptic plasticity were chosen: C57BL/6J and Fmr1^−/y on the C57BL/6J background, and 129SVE and Hevin^−/− (Sparcl1^−/−) on the 129SVE background. Like rats, hippocampal slices from all of the mice showed test pulse‐induced depression early during development that was gradually resolved with maturation by 5 weeks. All the mouse strains showed a gradual progression between P10‐P35 in the expression of short‐term potentiation (STP), lasting ≤1 hr. In the 129SVE mice, L‐LTP onset (>25% of slices) occurred by 3 weeks, reliable L‐LTP (>50% slices) was achieved by 4 weeks, and Hevin^−/− advanced this profile by 1 week. In the C57BL/6J mice, L‐LTP onset occurred significantly later, over 3–4 weeks, and reliability was not achieved until 5 weeks. Although some of the Fmr1^−/y mice showed L‐LTP before 3 weeks, reliable L‐LTP also was not achieved until 5 weeks. L‐LTP onset was not advanced in any of the mouse genotypes by multiple bouts of theta‐burst stimulation at 90 or 180 min intervals. These findings show important species differences in the onset of STP and L‐LTP, which occur at the same age in rats but are sequentially acquired in mice.

中文翻译：

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小鼠海马体持久长时程增强的发育开始。

长期增强 (LTP) 分析为了解学习和记忆的细胞机制提供了一个强有力的窗口。先前的工作表明，晚期 LTP (L-LTP) 持续 > 3 小时，在大鼠海马区 CA1 的辐射层的出生后第 12 天 (P12) 突然发生。此处的目标是确定导致小鼠海马体中 L-LTP 的突触可塑性的发育概况。选择了已知影响突触可塑性的两种小鼠品系和两种突变：C57BL/6J 和Fmr1 ^-/y在 C57BL/6J 背景上，以及 129SVE 和Hevin ^-/- ( Sparcl1 ^-/-) 在 129SVE 背景上。与大鼠一样，来自所有小鼠的海马体切片在发育早期显示测试脉冲诱发的抑郁症，随着 5 周的成熟逐渐消退。所有小鼠品系的短期增强 (STP) 表达在 P10-P35 之间呈逐渐进展，持续时间≤1 小时。在 129SVE 小鼠中，L-LTP 开始（>25% 的切片）发生在 3 周时，可靠的 L-LTP（>50% 切片）在 4 周时实现，Hevin -/- 将此概况提前1^周。在 C57BL/6J 小鼠中，L-LTP 的发生时间明显较晚，超过 3-4 周，直到 5 周后才达到可靠性。尽管一些Fmr1 ^−/y小鼠在 3 周前显示出 L-LTP，可靠的 L-LTP 也直到 5 周才达到。通过以 90 或 180 分钟为间隔的多次 θ 爆发刺激，任何小鼠基因型的 L-LTP 发作都没有提前。这些发现显示了 STP 和 L-LTP 发作的重要物种差异，它们发生在同一年龄的大鼠中，但在小鼠中依次获得。