Shim Hyun Joon, Lee Lae Hyung, Huh Youngbuhm, Lee So Yoon, Yeo Seung Geun
Department of Otorhinolaryngology, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
Acta Otolaryngol. 2012 Jan;132(1):44-50. doi: 10.3109/00016489.2011.622785. Epub 2011 Nov 6.
We suggest that age-induced changes of serotonin, N-methyl-d-aspartate receptor (NMDAR), and glutamate decarboxylase (GAD) expression in rats are dependent on the specific location in the central auditory system (CAS).
Despite the importance of understanding changes in neurotransmitters during presbycusis, only a few studies have assessed age-associated changes in neurotransmitter at each level of the CAS. We therefore evaluated effects of aging on neurotransmission in the CAS of rats.
The concentrations of serotonin, NMDAR, and GAD were assayed immunohistochemically in the cochlear nucleus (CN), superior olivary nucleus (SON), inferior colliculus (IC), medial geniculate body (MGB), and auditory cortex (AC) of Sprague-Dawley rats, aged 2 weeks (n = 20) or 24 months (n = 20).
The total number of neuronal cell bodies of the CAS did not differ significantly at each level between young and aged rats (p > 0.05). Serotonin expression was increased with age in the IC and MGB, but decreased in the CN, SON, and AC (p < 0.05). NMDAR was significantly higher in the CN, MGB, and AC of aged compared with young rats, but was significantly decreased over time in the SOC and IC (p < 0.05). GAD67 was increased with age in the MGB and AC and decreased in the CN and SON (p < 0.05), but was not changed in the IC.
我们认为，年龄引起的大鼠血清素、N-甲基-D-天冬氨酸受体（NMDAR）和谷氨酸脱羧酶（GAD）表达变化取决于中枢听觉系统（CAS）中的特定位置。
尽管了解老年性聋期间神经递质变化很重要，但只有少数研究评估了CAS各水平与年龄相关的神经递质变化。因此，我们评估了衰老对大鼠CAS神经传递的影响。
采用免疫组织化学方法检测2周龄（n = 20）或24月龄（n = 20）的Sprague-Dawley大鼠耳蜗核（CN）、上橄榄核（SON）、下丘（IC）、内侧膝状体（MGB）和听觉皮层（AC）中血清素、NMDAR和GAD的浓度。
年轻和老年大鼠各水平的CAS神经元细胞体总数无显著差异（p > 0.05）。血清素表达在IC和MGB中随年龄增加，但在CN、SON和AC中降低（p < 0.05）。与年轻大鼠相比，老年大鼠CN、MGB和AC中的NMDAR显著更高，但在SOC和IC中随时间显著降低（p < 0.05）。GAD67在MGB和AC中随年龄增加，在CN和SON中降低（p < 0.05），但在IC中无变化。
