Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Neuroreport. 2024 Aug 7;35(11):729-733. doi: 10.1097/WNR.0000000000002065. Epub 2024 Jun 3.
Solute transport in the brain is essential for maintaining cerebral homeostasis. Recent studies have shown that neuronal activity enhances the transport of cerebrospinal fluid solutes, but its impact on interstitial solute transport has not been established. In this study, we investigated whether neuronal activity affects the transport of interstitial solutes.
Fluorescent Texas Red ovalbumin was injected intracortically into the unilateral sensorimotor area of the Sprague-Dawley rats. Regional neuronal activity around the injection site was elicited by transdermal electrical stimulation of a corresponding forelimb for 90 min ( n = 6). The control group of rats ( n = 6) did not receive any electrical stimulation. Subsequently, the spatial distributions of the tracer over the cortical surface and from the brain sections were imaged and compared between two groups. The ovalbumin fluorescence from the cervical lymph nodes was also compared between the groups to evaluate the effect of neuronal activity on solute clearance from the brain.
Tracer distribution over the brain surface/sections revealed a significantly higher uptake of ovalbumin in the hemisphere ipsilateral to the injection among the stimulated animals compared to the unstimulated group. This difference, however, was not seen in the hemisphere contralateral to injection. A trace amount of ovalbumin in the lymph nodes was equivalent between the groups, which indicated a considerable time needed for interstitial solutes to be drained from the brain.
The results suggest that neuronal activity enhances interstitial solute transport, calling for further examination of ultimate routes and mechanisms for brain solute clearance.
脑内溶质转运对于维持脑内环境稳定至关重要。最近的研究表明，神经元活动增强了脑脊液溶质的转运，但神经元活动对细胞间溶质转运的影响尚未确定。在本研究中，我们研究了神经元活动是否影响细胞间溶质的转运。
将荧光桃红卵清蛋白（Fluorescent Texas Red ovalbumin）皮质内注射到 Sprague-Dawley 大鼠单侧感觉运动区。通过对相应前肢进行经皮电刺激 90 分钟（n=6）来引发注射部位周围的区域神经元活动。对照组大鼠（n=6）未接受任何电刺激。随后，比较两组之间在皮质表面和脑切片上示踪剂的空间分布。比较两组之间从颈部淋巴结中的卵清蛋白荧光来评估神经元活动对脑内溶质清除的影响。
脑表面/脑切片上的示踪剂分布显示，与未刺激组相比，刺激动物注射侧大脑半球对卵清蛋白的摄取明显增加。然而，在对侧大脑半球中未观察到这种差异。两组之间淋巴结中的卵清蛋白含量相当，这表明细胞间溶质需要相当长的时间才能从脑内排出。
结果表明神经元活动增强了细胞间溶质转运，需要进一步研究脑溶质清除的最终途径和机制。
