Normal aging is associated with significant deleterious cerebrovascular changes; these have been implicated in disease pathogenesis and increased susceptibility to ischemic injury. Although these changes are well documented in the brain, few studies have been conducted in the spinal cord. Here, we utilize specialized contrast-enhanced ultrasound (CEUS) imaging to investigate age-related changes in cervical spinal vascular anatomy and hemodynamics in male Fisher 344 rats, a common strain in aging research. Aged rats (24–26 months, N = 6) exhibited significant tortuosity in the anterior spinal artery and elevated vascular resistance compared to adults (4–6 months, N = 6; tortuosity index 2.20 ± 0.15 vs 4.74 ± 0.45, p < .05). Baseline blood volume was lower in both larger vessels and the microcirculation in the aged cohort, specifically in white matter (4.44e14 ± 1.37e13 vs 3.66e14 ± 2.64e13 CEUS bolus area under the curve, p < .05). To elucidate functional differences, animals were exposed to a hypoxia challenge, whereas adult rats exhibited significant functional hyperemia in both gray matter (GM) and white matter (WM) (GM: 1.13 ± 0.10-fold change from normoxia, p < .05; WM: 1.16 ± 0.13, p < .05), aged rats showed no response. Immunohistochemistry revealed reduced pericyte coverage and activated microglia behavior in aged rats, which may partially explain the lack of vascular response. This study provides the first in vivo description of age-related hemodynamic differences in the cervical spinal cord.

中文翻译：

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造影剂增强超声成像可检测正常衰老大鼠颈椎微血管系统的解剖和功能变化


正常衰老与显著的有害脑血管变化有关;这些与疾病发病机制和缺血性损伤易感性增加有关。尽管这些变化在大脑中有很好的记录，但在脊髓中进行的研究很少。在这里，我们利用专门的对比增强超声 （CEUS） 成像来研究雄性 Fisher 344 大鼠（衰老研究中的常见菌株）颈椎血管解剖结构和血流动力学的年龄相关变化。与成人 （4-6 个月，N = 6;迂曲指数 2.20 ± 0.15 对 4.74 ± 0.45，p < .05）相比，老年大鼠 （24-26 个月，N = 6） 表现出明显的脊髓前动脉迂曲和血管阻力升高。老年队列中较大血管和微循环的基线血容量较低，特别是在白质中 （4.44e14 ± 1.37e13 vs 3.66e14 ± 2.64e13 CEUS 推注曲线下面积，p < .05）。为了阐明功能差异，动物暴露于缺氧挑战，而成年大鼠在灰质 （GM） 和白质 （WM） 中均表现出显着的功能性充血 （GM：与常氧相比变化 1.13 ± 0.10 倍，p < .05;WM： 1.16 ± 0.13， p < .05），老年大鼠无反应。免疫组化显示老年大鼠的周细胞覆盖率降低并激活了小胶质细胞行为，这可能部分解释了缺乏血管反应。本研究首次提供了颈脊髓中与年龄相关的血流动力学差异的体内描述。