Hyde G E, Durham D
Department of Otolaryngology, University of Washington, Seattle 98195.
J Comp Neurol. 1990 Jul 15;297(3):329-39. doi: 10.1002/cne.902970302.
Changes in cytochrome oxidase (CO) activity were studied in the chick brainstem auditory nuclei, n. magnocellularis (NM) and n. laminaris (NL), following unilateral cochlea removal. Chickens aged 10 days or 56 weeks underwent unilateral cochlea removal. Following survival periods of 30 minutes to 14 days for the 10-day-old birds and 6 hours or 14 days for the 56-week-old birds, the animals were perfused with paraformaldehyde/glutaraldehyde fixative. Cryostat sections of the brainstem were then prepared for CO histochemistry. Microdensitometry was used to quantify the difference in CO staining in NM and NL ipsilateral and contralateral to the cochlea removal. Since the cochlea projects to the ipsilateral NM, the contralateral NM was used as a within-animal control. In normal chickens, NM cell bodies and the cell bodies and dendrites of NL neurons stain darkly for CO in both young and adult birds. In 10-day-old birds, there is no significant change in CO staining in NM from 30 minutes to 3 hours after cochlea removal. Then, a rapid biphasic change in CO staining was found in the ipsilateral NM. An increase in staining was observed 6 to 24 hours postoperatively, followed by a decrease in CO staining at 3- to 14-day survival times. In the 56-week-old birds, no increases in CO staining were observed 6 hours after cochlea removal, but a decrease in CO staining was found 14 days postoperatively. In NL, no changes were observed until 3 days (10-day-old birds) or 14 days (56-week-old birds) after cochlea removal. Then a decrease in CO staining was observed in the dendritic and glial/fiber regions of NL containing axons from the deafferented NM. Thus it appears that afferent input has a regulatory effect on the oxidative metabolism of neurons in the chicken auditory brainstem nuclei, an effect that differs with the age of the animal at the time of afferent manipulation.
在单侧切除耳蜗后，研究了雏鸡脑干听觉核团，即大细胞神经核（NM）和层状神经核（NL）中细胞色素氧化酶（CO）活性的变化。10日龄或56周龄的雏鸡接受单侧耳蜗切除。10日龄的雏鸡存活30分钟至14天，56周龄的雏鸡存活6小时或14天，之后用多聚甲醛/戊二醛固定液灌注动物。然后制备脑干的低温恒冷切片用于CO组织化学分析。使用显微密度测定法来量化切除耳蜗同侧和对侧的NM和NL中CO染色的差异。由于耳蜗投射到同侧的NM，因此将对侧的NM用作动物体内对照。在正常雏鸡中，无论是幼鸟还是成年鸟，NM的细胞体以及NL神经元的细胞体和树突对CO的染色都很深。在10日龄的雏鸡中，切除耳蜗后30分钟至3小时，NM中的CO染色没有显著变化。然后，在同侧的NM中发现了CO染色的快速双相变化。术后6至24小时观察到染色增加，随后在存活3至14天时CO染色减少。在56周龄的雏鸡中，切除耳蜗后6小时未观察到CO染色增加，但术后14天发现CO染色减少。在NL中，直到切除耳蜗后3天（10日龄雏鸡）或14天（56周龄雏鸡）才观察到变化。然后在NL的含有来自去传入NM轴突的树突和神经胶质/纤维区域观察到CO染色减少。因此，传入输入似乎对鸡听觉脑干核团中神经元的氧化代谢具有调节作用，这种作用在传入操作时因动物年龄而异。
