Kent P, Anisman H, Merali Z
School of Psychology, University of Ottawa, Ontario, Canada.
Life Sci. 1998;62(2):103-14. doi: 10.1016/s0024-3205(97)01057-6.
The neurochemical mechanisms underlying the coincident activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system in response to stress remain unclear. Central injection of the neuropeptide bombesin (BN) potently stimulates the release of epinephrine from the adrenal medulla, adrenocorticotropic hormone (ACTH) from the pituitary gland, and elicits behaviors typically associated with increased emotionality and arousal. The current studies assessed whether stress is associated with 1) fluctuations in the endogenous regional levels of BN-like peptides and/or 2) changes in BN receptor density. Male Sprague-Dawley rats received either no treatment or were subjected to acute immobilization stress for 10, 30 or 120 min. Plasma ACTH levels increased in response to stress, peaking at 30 min. BN-like immunoreactivity increased significantly at the hypothalamus and medulla, within 30 min; however with more sustained immobilization (120 min) BN-like immunoreactivity declined to control levels. Levels of BN-like peptides remained unchanged in several other regions, including the hippocampus, striatum, midbrain, pituitary, and pons. Autoradiographic analysis revealed that the density of BN receptor varied in a regionally specific manner. Significant stress related increases in binding were found at the nucleus of the solitary tract (at 30 and 120 min), and at the paraventricular (at 120 min) and arcuate nuclei (at 120 min) of the hypothalamus. These data indicate the BN-like peptides may play a role in the mediation and/or modulation of response to stress.
下丘脑-垂体-肾上腺（HPA）轴和交感神经系统在应激反应中同时激活的神经化学机制仍不清楚。向中枢注射神经肽铃蟾肽（BN）可有效刺激肾上腺髓质释放肾上腺素、垂体释放促肾上腺皮质激素（ACTH），并引发通常与情绪和觉醒增加相关的行为。当前的研究评估了应激是否与1）内源性区域铃蟾肽样肽水平的波动和/或2）BN受体密度的变化有关。雄性Sprague-Dawley大鼠要么不接受治疗，要么接受1０、30或120分钟的急性固定应激。应激反应使血浆促肾上腺皮质激素水平升高，在30分钟时达到峰值。下丘脑和延髓的铃蟾肽样免疫反应性在30分钟内显著增加；然而，随着固定时间延长（120分钟），铃蟾肽样免疫反应性下降至对照水平。包括海马、纹状体、中脑、垂体和脑桥在内的其他几个区域的铃蟾肽样肽水平保持不变。放射自显影分析显示，BN受体密度存在区域特异性变化。在孤束核（30分钟和120分钟时）、下丘脑室旁核（120分钟时）和弓状核（120分钟时）发现了与应激相关的结合显著增加。这些数据表明，铃蟾肽样肽可能在应激反应的介导和/或调节中发挥作用。
