Department of Anatomy, Histology and Neurosciences, Universidad Autónoma de Madrid, 28029 Madrid, Spain.
Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, 28223 Madrid, Spain.
Cells. 2022 Feb 17;11(4):717. doi: 10.3390/cells11040717.
Aging is accompanied by a decline in cognition that can be due to a lower IGF-I level. We studied response facilitation induced in primary somatosensory (S1) cortical neurons by repetitive stimulation of whiskers in young and old mice. Layer 2/3 and 5/6 neurons were extracellularly recorded in young (≤ 6 months of age) and old (≥ 20 month of age) anesthetized mice. IGF-I injection in S1 cortex (10 nM; 0.2 μL) increased whisker responses in young and old animals. A stimulation train at 8 Hz induced a long-lasting response facilitation in only layer 2/3 neurons of young animals. However, all cortical neurons from young and old animals showed long-lasting response facilitation when IGF-I was applied in the S1 cortex. The reduction in response facilitation in old animals can be due to a reduction in the IGF-I receptors as was indicated by the immunohistochemistry study. Furthermore, a reduction in the performance of a whisker discrimination task was observed in old animals. In conclusion, our findings indicate that there is a reduction in the synaptic plasticity of S1 neurons during aging that can be recovered by IGF-I. Therefore, it opens the possibility of use IGF-I as a therapeutic tool to ameliorate the effects of heathy aging.
衰老伴随着认知能力的下降，这可能是由于 IGF-I 水平降低所致。我们研究了在年轻和老年小鼠中通过胡须重复刺激诱导的初级体感（S1）皮质神经元的反应易化。在年轻（≤ 6 个月龄）和老年（≥ 20 月龄）麻醉小鼠中，对第 2/3 层和第 5/6 层神经元进行了细胞外记录。IGF-I 注射到 S1 皮层（10 nM；0.2 μL）增加了年轻和老年动物的胡须反应。只有在年轻动物的第 2/3 层神经元中，8 Hz 的刺激序列才能诱导出持久的反应易化。然而，当 IGF-I 施加到 S1 皮层时，来自年轻和老年动物的所有皮质神经元均显示出持久的反应易化。老年动物中反应易化的减少可能是由于 IGF-I 受体的减少，免疫组织化学研究表明了这一点。此外，在老年动物中观察到胡须辨别任务的表现下降。总之，我们的发现表明，S1 神经元的突触可塑性在衰老过程中会降低，而 IGF-I 可以恢复这种可塑性。因此，它为使用 IGF-I 作为治疗工具来改善健康衰老的影响开辟了可能性。
