Table_1_Corticotropin-Releasing Factor-Producing Cells in the Paraventricular Nucleus of the Hypothalamus and Extended Amygdala Show Age-Dependent FOS and FOSB/DeltaFOSB Immunoreactivity in Acute and Chronic Stress Models in the Rat.docx

Corticotropin-releasing factor (CRF) immunoreactive (ir) neurons of the paraventricular nucleus of the hypothalamus (PVN) play pivotal role in the coordination of stress response. CRF-producing cells in the central nucleus of amygdala (CeA) and oval division of the bed nucleus of stria terminalis (BNSTov) are also involved in stress adaptation and mood control. Immediate early gene products, subunits of the transcription factor activator protein 1 (AP1) are commonly used as acute (FOS) and/or chronic (FOSB/deltaFOSB) markers for the neuronal activity in stress research. It is well known that the course of aging affects stress adaptation, but little is known about the aging-related stress sensitivity of CRF neurons. To the best of our knowledge, the stress-induced neuronal activity of CRF neurons in the course of aging in acute and chronic stress models was not studied systematically yet. Therefore, the aim of the present study was to quantify the acute restraint stress (ARS) and chronic variable mild stress (CVMS) evoked neuronal activity in CRF cells of the PVN, CeA, and BNSTov using triple-label immunofluorescence throughout the whole lifespan in the rat. We hypothesized that the FOS and FOSB content of CRF cells upon ARS or CVMS decreases with age. Our results showed that the FOS and FOSB response to ARS declined with age in the PVN-CRF cells. BNSTov and CeA CRF cells did not show remarkable stress-induced elevation of these markers neither in ARS, nor in CVMS. Exposure to CVMS resulted in an age-independent significant increase of FOSB/delta FOSB immunosignal in PVN-CRF neurons. Unexpectedly, we detected a remarkable stress-independent FOSB/deltaFOSB signal in CeA- and BNSTov-CRF cells that declined with the course of aging. In summary, PVN-CRF cells show decreasing acute stress sensitivity (i.e., FOS and FOSB immunoreactivity) with the course of aging, while their (FOSB/deltaFOSB) responsivity to chronic challenge is maintained till senescence. Stress exposure does not affect the occurrence of the examined Fos gene products in CeA- and BNSTov-CRF cells remarkably suggesting that their contribution to stress adaptation response does not require AP1-controlled transcriptional changes.

下丘脑室旁核（PVN）中的促皮质素释放因子（CRF）免疫反应性（ir）神经元在协调应激反应中发挥着关键作用。杏仁核中央核（CeA）及终纹床核的椭圆形区域（BNSTov）中产生的CRF细胞亦参与应激适应与情绪调节。即时早期基因产物，转录因子激活蛋白1（AP1）的亚基，常被用作应激研究中神经元活动的急性（FOS）及/或慢性（FOSB/deltaFOSB）标记。众所周知，衰老过程影响应激适应，但对于CRF神经元与衰老相关的应激敏感性所知甚少。据我们所知，尚未系统地研究在急性与慢性应激模型中，CRF神经元在衰老过程中的应激诱导神经元活动。因此，本研究旨在通过在整个寿命期间使用三重标记免疫荧光技术，量化大鼠PVN、CeA和BNSTov中CRF细胞的急性束缚应激（ARS）和慢性可变轻度应激（CVMS）引发的神经元活动。我们假设在ARS或CVMS作用下，CRF细胞的FOS和FOSB含量随年龄增长而降低。我们的结果显示，PVN-CRF细胞的FOS和FOSB对ARS的反应随年龄增长而减弱。BNSTov和CeA的CRF细胞在ARS和CVMS中均未表现出显著的应激诱导的这些标记物升高。CVMS暴露导致PVN-CRF神经元中FOSB/delta FOSB免疫信号随年龄增长而独立于应激反应显著增加。令人惊讶的是，我们在CeA-和BNSTov-CRF细胞中检测到显著的、与应激无关的FOSB/deltaFOSB信号，该信号随衰老过程而减弱。总之，PVN-CRF细胞在衰老过程中表现出急性应激敏感性（即FOS和FOSB免疫反应性）的降低，而其对慢性挑战的响应性直至衰老期仍得以维持。应激暴露对CeA-和BNSTov-CRF细胞中检查的Fos基因产物的影响不显著，这表明其对应激适应反应的贡献不依赖于AP1控制的转录变化。