Sallaz M, Jourdan F
Laboratoire de Physiologie neurosensorielle, URA CNRS 180, Université Claude Bernard/Lyon 1, Villeurbanne, France.
Brain Res. 1996 May 20;721(1-2):66-75. doi: 10.1016/0006-8993(96)00150-3.
Expression of the proto-oncogene c-fos is known to increase in granule cells of the olfactory bulb following a sustained olfactory stimulation. Most granule cells displaying high levels of Fos accumulation are located in the bulbar columns defined by the odour-induced foci of high 2-deoxyglucose glomerular uptake. The present studies were undertaken in order to assess the possible involvement of centrifugal afferents in the modulation of odour-induced patterns of either 2-deoxyglucose accumulation or c-fos expression in the olfactory bulb. A unilateral olfactory peduncle section had no effect on the odour-induced 2-deoxyglucose foci but induced a significant decrease in the number of Fos-containing neurons in odour-selective areas of both olfactory bulbs, ipsilateral and contralateral to the lesion. This suppressive effect was much more pronounced in the side ipsilateral to the peduncle section. It is concluded that c-fos expression induced by a sustained stimulation with propionic acid vapours is not only determined by the olfactory peripheral input but also by afferents of central origin. In order to estimate the contingent involvements of the cholinergic and noradrenergic afferents in this control of c-fos expression, we attempted to mimic the effects of the surgical deafferentation on odour-induced c-fos expression by using a pharmacological approach with selective cholinergic and noradrenergic antagonists. The beta-adrenergic antagonist propanolol induced a suppression of the odour-related patterns of Fos accumulation similar to the one caused by the surgical deafferentation of the olfactory bulb. The muscarinic antagonist scopolamine did not alter c-fos expression in the odour-selective area but increased significantly Fos labelling in the other bulbar aspects. Pharmacological investigations indicate that the noradrenergic and cholinergic centrifugal systems are likely involved in the central modulation of c-fos expression in the OB. The Fos protein could be expressed as an early nuclear signal triggering further long-term modifications of the neuronal phenotype, in certain conditions of sensory stimulation involving the activation of centrifugal systems.
已知原癌基因c-fos的表达在持续嗅觉刺激后会在嗅球颗粒细胞中增加。大多数显示高水平Fos积累的颗粒细胞位于由气味诱导的高2-脱氧葡萄糖肾小球摄取灶所定义的球柱中。进行本研究是为了评估离心传入神经在调节嗅球中气味诱导的2-脱氧葡萄糖积累模式或c-fos表达模式中可能的参与情况。单侧嗅柄切断对气味诱导的2-脱氧葡萄糖灶没有影响，但导致双侧嗅球（损伤同侧和对侧）气味选择性区域中含Fos神经元的数量显著减少。这种抑制作用在嗅柄切断侧同侧更为明显。结论是，丙酸蒸汽持续刺激诱导的c-fos表达不仅由嗅觉外周输入决定，还由中枢起源的传入神经决定。为了估计胆碱能和去甲肾上腺素能传入神经在这种c-fos表达控制中的具体参与情况，我们试图通过使用选择性胆碱能和去甲肾上腺素能拮抗剂的药理学方法来模拟手术去传入神经对气味诱导的c-fos表达的影响。β-肾上腺素能拮抗剂普萘洛尔诱导了与嗅球手术去传入神经引起的类似的Fos积累气味相关模式的抑制。毒蕈碱拮抗剂东莨菪碱没有改变气味选择性区域中的c-fos表达，但显著增加了球其他方面的Fos标记。药理学研究表明，去甲肾上腺素能和胆碱能离心系统可能参与了嗅球中c-fos表达的中枢调节。在涉及离心系统激活的某些感觉刺激条件下，Fos蛋白可以作为触发神经元表型进一步长期改变的早期核信号表达。
