Spontaneous and sensory-evoked activity in mouse olfactory sensory neurons with defined odorant receptors
Spontaneous and sensory-evoked activity in mouse olfactory sensory neurons with defined odorant receptors
复制标题
DOI：
10.1152/jn.00910.2012
复制
发表时间：
2013-07-01
影响因子：
2.5
通讯作者：
Ma, Minghong
中科院分区：
文献类型：
--
作者：
Connelly, Timothy;Savigner, Agnes;Ma, Minghong
感官系统需要在嘈杂的背景下梳理出刺激引起的活动。在嗅觉系统中，嗅觉感觉神经元（OSN）的气味反应谱取决于它所表达的气味受体的类型。OSNs也表现出自发活动，这在建立适当的突触连接中起作用，也可能增加细胞的敏感性。然而，自发活动的起源以及它是否通知感觉诱发活动尚不清楚。我们通过检查完整嗅上皮中具有明确气味受体的遗传标记小鼠osn的膜片钳记录来解决这些问题。我们发现，表达不同气味受体的osn具有显著不同的基础活性率。此外，表达失活突变体I7受体的osn完全缺乏自发活性，尽管能够在电流注射响应中激发动作电位。这一发现有力地表明，OSN的自发放电源于其G蛋白偶联气味受体的自发激活。此外，表达同一受体的osn在其自发活动中表现出相当大的差异，并且在气味刺激下变化更大。有趣的是，这些神经元的自发活动和感觉诱发活动之间没有显著的相关性。本研究表明，气味受体类型决定了OSNs的自发放电率，但基础活性与近饱和气味刺激诱导的活性无关。讨论了这些发现对嗅觉信息处理的影响。
Sensory systems need to tease out stimulation-evoked activity against a noisy background. In the olfactory system, the odor response profile of an olfactory sensory neuron (OSN) is dependent on the type of odorant receptor it expresses. OSNs also exhibit spontaneous activity, which plays a role in establishing proper synaptic connections and may also increase the sensitivity of the cells. However, where the spontaneous activity originates and whether it informs sensory-evoked activity remain unclear. We addressed these questions by examining patch-clamp recordings of genetically labeled mouse OSNs with defined odorant receptors in intact olfactory epithelia. We show that OSNs expressing different odorant receptors had significantly different rates of basal activity. Additionally, OSNs expressing an inactive mutant I7 receptor completely lacked spontaneous activity, despite being able to fire action potentials in response to current injection. This finding strongly suggests that the spontaneous firing of an OSN originates from the spontaneous activation of its G protein-coupled odorant receptor. Moreover, OSNs expressing the same receptor displayed considerable variation in their spontaneous activity, and the variation was broadened upon odor stimulation. Interestingly, there is no significant correlation between the spontaneous and sensory-evoked activity in these neurons. This study reveals that the odorant receptor type determines the spontaneous firing rate of OSNs, but the basal activity does not correlate with the activity induced by near-saturated odor stimulation. The implications of these findings on olfactory information processing are discussed.