Lymer Jennifer, Robinson Alana, Winters Boyer D, Choleris Elena
Department of Psychology and Neuroscience Program, University of Guelph, Guelph, ON N1G 2W1, Canada.
Department of Psychology and Neuroscience Program, University of Guelph, Guelph, ON N1G 2W1, Canada.
Psychoneuroendocrinology. 2017 Mar;77:131-140. doi: 10.1016/j.psyneuen.2016.11.019. Epub 2016 Nov 24.
Through rapid mechanisms of action, estrogens affect learning and memory processes. It has been shown that 17β-estradiol and an Estrogen Receptor (ER) α agonist enhances performance in social recognition, object recognition, and object placement tasks when administered systemically or infused in the dorsal hippocampus. In contrast, systemic and dorsal hippocampal ERβ activation only promote spatial learning. In addition, 17β-estradiol, the ERα and the G-protein coupled estrogen receptor (GPER) agonists increase dendritic spine density in the CA1 hippocampus. Recently, we have shown that selective systemic activation of the GPER also rapidly facilitated social recognition, object recognition, and object placement learning in female mice. Whether activation the GPER specifically in the dorsal hippocampus can also rapidly improve learning and memory prior to acquisition is unknown. Here, we investigated the rapid effects of infusion of the GPER agonist, G-1 (dose: 50nM, 100nM, 200nM), in the dorsal hippocampus on social recognition, object recognition, and object placement learning tasks in home cage. These paradigms were completed within 40min, which is within the range of rapid estrogenic effects. Dorsal hippocampal administration of G-1 improved social (doses: 50nM, 200nM G-1) and object (dose: 200nM G-1) recognition with no effect on object placement. Additionally, when spatial cues were minimized by testing in a Y-apparatus, G-1 administration promoted social (doses: 100nM, 200nM G-1) and object (doses: 50nM, 100nM, 200nM G-1) recognition. Therefore, like ERα, the GPER in the hippocampus appears to be sufficient for the rapid facilitation of social and object recognition in female mice, but not for the rapid facilitation of object placement learning. Thus, the GPER in the dorsal hippocampus is involved in estrogenic mediation of learning and memory and these effects likely occur through rapid signalling mechanisms.
通过快速作用机制，雌激素会影响学习和记忆过程。研究表明，全身给药或注入背侧海马体时，17β-雌二醇和雌激素受体（ER）α激动剂可提高社交识别、物体识别和物体放置任务中的表现。相比之下，全身和背侧海马体ERβ激活仅促进空间学习。此外，17β-雌二醇、ERα和G蛋白偶联雌激素受体（GPER）激动剂可增加海马体CA1区的树突棘密度。最近，我们发现选择性全身激活GPER也能迅速促进雌性小鼠的社交识别、物体识别和物体放置学习。在背侧海马体中特异性激活GPER是否也能在获取前迅速改善学习和记忆尚不清楚。在此，我们研究了在背侧海马体中注入GPER激动剂G-1（剂量：50nM、100nM、200nM）对笼内社交识别、物体识别和物体放置学习任务的快速影响。这些实验范式在40分钟内完成，这在雌激素快速作用的范围内。背侧海马体给予G-1可改善社交识别（剂量：50nM、200nM G-1）和物体识别（剂量：200nM G-1），对物体放置无影响。此外，当在Y型装置中进行测试以尽量减少空间线索时，给予G-1可促进社交识别（剂量：100nM、200nM G-1）和物体识别（剂量：50nM、100nM、200nM G-1）。因此，与ERα一样，海马体中的GPER似乎足以迅速促进雌性小鼠的社交和物体识别，但不足以迅速促进物体放置学习。因此，背侧海马体中的GPER参与了学习和记忆的雌激素介导作用，这些作用可能通过快速信号机制发生。
