Saint Marie R L, Luo L, Ryan A F
Neuroanatomy Department, House Ear Institute, Los Angeles, California 90057, USA.
J Comp Neurol. 1999 Feb 8;404(2):258-70. doi: 10.1002/(sici)1096-9861(19990208)404:2<258::aid-cne9>3.0.co;2-u.
Induction of the cellular fos gene (c-fos) is one of the earliest transcriptional changes observed following neuronal excitation. Although not an activity marker in the strict electrophysiological sense, many neurons in the central nervous system increase their c-fos expression after periods of sustained stimulation at physiological levels of intensity. In the present study, induction of c-fos mRNA expression was examined in the auditory brainstem after 1 hour of continuous free-field acoustic stimulation. Sprague-Dawley rats were exposed to pure tones of 2, 8, 16, or 32 kHz or half-octave noise bands centered on 2, 8, or 32 kHz at 80-120 dB SPL. Stimulation-induced c-fos mRNA expression was evident at all levels of the auditory brainstem, and this expression was intensity dependent. In some brain areas, induced expression manifested a clear tonotopic organization, i.e., in dorsal, posteroventral, and anteroventral cochlear nuclei, and in the medial nucleus of the trapezoid body. The inferior colliculus exhibited multiple tonotopic representations. The dorsal nucleus of the lateral lemniscus had a crude tonotopy. Although expression was present, tonotopy was not evident in periolivary nuclei or in the ventral or intermediate nuclei of the lateral lemniscus. Free-field diotic stimulation did not induce c-fos mRNA expression in the medial or lateral superior olivary nuclei. Expression was induced in the lateral superior olive by dichotic stimulation (after a unilateral cochlear ablation), and that expression was tonotopically organized. The results suggest that stimulation-induced c-fos mRNA expression can be an effective way of mapping neuronal activity in the central auditory system under both normal and pathological conditions.
细胞fos基因（c-fos）的诱导是神经元兴奋后最早观察到的转录变化之一。虽然从严格的电生理学意义上讲它不是一个活动标记，但中枢神经系统中的许多神经元在受到生理强度的持续刺激后会增加其c-fos表达。在本研究中，在连续1小时的自由场声刺激后，检测了听觉脑干中c-fos mRNA表达的诱导情况。将Sprague-Dawley大鼠暴露于2、8、16或32kHz的纯音或中心频率为2、8或32kHz的半倍频程噪声带，声压级为80-120dB SPL。刺激诱导的c-fos mRNA表达在听觉脑干的所有水平均很明显，且这种表达是强度依赖性的。在一些脑区，诱导表达表现出明显的音调组织，即在背侧、后腹侧和前腹侧耳蜗核以及梯形体内侧核中。下丘表现出多个音调表征。外侧丘系背核有粗略的音调定位。虽然有表达，但在橄榄周核或外侧丘系的腹侧或中间核中音调定位不明显。自由场双耳刺激未诱导内侧或外侧上橄榄核中的c-fos mRNA表达。双耳刺激（单侧耳蜗切除后）可诱导外侧上橄榄核中的表达，且该表达具有音调组织。结果表明，刺激诱导的c-fos mRNA表达可以是在正常和病理条件下绘制中枢听觉系统神经元活动的有效方法。
