CONTROLLED SUPERFUSION OF THE RAT SPINAL-CORD FOR STUDYING NONSYNAPTIC TRANSMISSION - AN AUTORADIOGRAPHIC ANALYSIS
CONTROLLED SUPERFUSION OF THE RAT SPINAL-CORD FOR STUDYING NONSYNAPTIC TRANSMISSION - AN AUTORADIOGRAPHIC ANALYSIS
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DOI：
10.1016/0165-0270(94)00176-h
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发表时间：
1995-05-01
影响因子：
3
通讯作者：
SANDKUHLER, J
中科院分区：
文献类型：
--
作者：
BECK, H;SCHROCK, H;SANDKUHLER, J
最近，有证据表明，中枢神经系统的长期变化是由神经肽的突触外扩散介导的（“体积传递”）。为了研究脊髓内容量传递的影响，我们建立了大鼠脊髓背控灌注技术。本文介绍了（2-[I-125]碘组氨酸）神经激肽A以0.05或50 μ M （10 μ l）浓度作用于脊髓背15、30或60 min后，其扩散、局部脊髓组织浓度和再分布的定量数据。计算机辅助密度测量对脊髓矢状面和横切面x线自显像进行分析。在所有实验条件下，放射性标记物在过度脊髓节段的扩散到达Rexed的V和VI层；灌注30min后测最大扩散（1.6 +/- 0.3 mm）。腹侧放射标记量随距离的增加而减少。神经激肽A （NKA）在深度为0.5 mm的脊髓浅表内获得最高的组织浓度，在用50 μ M NKA灌注15或30分钟后，其浓度范围为700至2000 pmol/g。因此，这些组织浓度比过浓液中NKA浓度低25-70倍。由于没有交换池的内容物，脊髓内的放射性在灌注60分钟后比灌注15或30分钟后要低。血液和尿液中放射性标记的检测表明毛细血管清除是相关的，并限制了肽在脊髓组织内的积累和向更深层的扩散。大鼠脊髓背的受控灌注是模拟内源性神经肽（如NKA）在强烈有害刺激下的脊髓释放的一种有效方法，它可以用于研究神经活性分子对完整脊髓网络中感觉信息加工的影响。
Recently, evidence has been raised that long-term changes in the central nervous system are mediated by extrasynaptic spread of neuropeptides ('volume transmission'). To study the effects of volume transmission in the spinal cord we developed the technique of controlled superfusion of the rat cord dorsum. This paper presents quantitative data about the spread, local spinal tissue concentration and redistribution of (2-[I-125]iodohistidyl)neurokinin A, applied for 15, 30 or 60 min to the spinal cord dorsum in concentrations of 0.05 or 50 mu M (10 mu l). Analysis of autoradiograms of sagittal and transverse spinal cord sections was done by computer-assisted densitometry. Under all experimental conditions, the spread of radiolabel into the superfused spinal cord segments reached Rexed's laminae V and VI; maximal spread (1.6 +/- 0.3 mm) was measured after superfusion for 30 min. The amount of radiolabel decreased in ventral direction as a function of distance. Highest tissue concentrations of neurokinin A (NKA) were obtained within the superficial spinal cord up to a depth of 0.5 mm and ranged from 700 to 2000 pmol/g following superfusions for 15 or 30 min with 50 mu M NKA. Thus, these tissue concentrations were 25-70 times lower than the concentration of NKA in the superfusate. Since pool content was not exchanged, the radioactivity within the spinal cord was lower after superfusion periods of 60 min than after 15 or 30 min. Detection of radiolabel in blood and urine suggests that capillary clearance is relevant and limits the accumulation of the peptide within the spinal cord tissue and the spread into deeper laminae. The controlled superfusion of the rat cord dorsum is a useful method to mimick the spinal release of endogenous neuropeptides such as NKA during intense noxious stimulation, and it can be employed for versatile investigations of the effects of neuroactive molecules on the processing of sensory information in the intact spinal network.