Merali Z, Kent P, Michaud D, McIntyre D, Anisman H
School of Psychology, University of Ottawa, 11 Marie Curie, Ottawa, ON, Canada K1N 6N5.
Brain Res. 2001 Jul 6;906(1-2):60-73. doi: 10.1016/s0006-8993(01)02556-2.
Lines of rats selectively bred for amygdala excitability, as reflected by kindling rates in response to electrical stimulation, also exhibit differences in tests of anxiety. Inasmuch as corticotropin-releasing hormone (CRH) and bombesin (BN) have been associated with anxiety, regional levels and release of these peptides, as well as plasma adrenocorticotropic hormone (ACTH) and corticosterone, were assessed in 'Slow' and 'Fast' seizing rats following predator exposure (ferret) or immobilization. Ferret exposure elicited a greater increase of plasma ACTH and corticosterone concentrations in the Slow than in the Fast rats. In contrast, immobilization provoked a greater rise of plasma ACTH levels in the Fast rats, paralleling the vigorous struggling observed in this line. In Slow rats, stressor exposure elicited increased levels of ir-BN at the anterior hypothalamus, and increased ir-CRH at the median eminence/arcuate nucleus (Me/Arc), paraventricular hypothalamic nucleus (PVN) and pituitary (Pit), whereas decreased levels of ir-BN were found at the nucleus tractus solitarius (NTS). Fast rats likewise showed decreased ir-BN at the NTS, but unlike the Slow rats, ir-CRH was reduced in the Me/Arc, PVN and Pit in response to both stressors. In vivo microdialysis experiments revealed that in response to ferret exposure, the Slow rats showed a greater CRH release at the central nucleus of the amygdala (CeA) as compared to Fast rats. However, immobilization elicited a more pronounced release of CRH in Fast than in Slow rats. Taken together, the results demonstrate that these two lines of rats show differential endocrinological and neurochemical response patterns to these stressors.
根据对电刺激的点燃率反映，经选择性培育以提高杏仁核兴奋性的大鼠品系，在焦虑测试中也表现出差异。鉴于促肾上腺皮质激素释放激素（CRH）和蛙皮素（BN）与焦虑有关，在暴露于捕食者（雪貂）或固定后，对“慢”和“快”发作的大鼠评估了这些肽的区域水平和释放情况，以及血浆促肾上腺皮质激素（ACTH）和皮质酮水平。与“快”大鼠相比，暴露于雪貂使“慢”大鼠的血浆ACTH和皮质酮浓度升高幅度更大。相反，固定使“快”大鼠的血浆ACTH水平升高幅度更大，这与该品系中观察到的剧烈挣扎情况相一致。在“慢”大鼠中，应激源暴露使下丘脑前部的免疫反应性蛙皮素（ir-BN）水平升高，使正中隆起/弓状核（Me/Arc）、室旁下丘脑核（PVN）和垂体（Pit）的免疫反应性CRH水平升高，而孤束核（NTS）的ir-BN水平降低。“快”大鼠在NTS同样显示ir-BN水平降低，但与“慢”大鼠不同的是，对两种应激源的反应均使Me/Arc、PVN和Pit中的ir-CRH减少。体内微透析实验显示，与“快”大鼠相比，暴露于雪貂时，“慢”大鼠在杏仁核中央核（CeA）释放的CRH更多。然而，固定使“快”大鼠释放的CRH比“慢”大鼠更明显。综上所述，结果表明这两个大鼠品系对这些应激源表现出不同的内分泌和神经化学反应模式。
