Abdulbasit Amin, Stephen Michael Fii, Shukurat Onaopemipo Amusa, Abdulmusawwir Alli-Oluwafuyi, Aminu Imam, Nnaemeka Tobechukwu Asogwa, Wahab Imam Abdulmajeed, Oluwaseun Aremu Adeyanju, Folajimi Olaseinde, Bilikis Aderonke Abolarinwa, Ridwan Babatunde Ibrahim, Victor Bamidele Owoyele
Department of Physiology, Faculty of Basic Medical Sciences, University of Ilorin, Nigeria.
Department of Physiology, Faculty of Basic Medical Sciences, University of Ilorin, Nigeria.
Pathophysiology. 2018 Mar;25(1):41-50. doi: 10.1016/j.pathophys.2017.12.002. Epub 2017 Dec 9.
Glucocorticoid receptors (GR) are ubiquitously expressed in metazoans. Different and contrasting phenotypes have been reported upon their activation. This study investigated the behavioral phenotypes characteristic of GR stimulation in male Wistar rats. Rats in each of the four groups of rats received one of the following treatments: distilled water (control) or one of three doses of dexamethasone (treatment) injected intraperitoneally for 7 days. The Rats were afterwards subjected to the Y maze, the elevated plus maze (EPM), the Morris water maze (MWM), and the novel object recognition (NOR) test. At the end of the study, the animals were anesthetized and neural activity from the prefrontal cortex recorded. Blood was collected via cardiac puncture to evaluate the levels of plasma insulin and glucose, and the prefrontal cortexes excised to determine the levels of insulin, markers of oxidative stress, and calcium in the homogenate. This study showed that treatment with dexamethasone significantly reduced the total and percentage alternation in the Y maze, but had no significant effect on object recognition in the NOR test, long-term and short-term spatial memory in the MWM, or anxiety-like behavior in the EPM. Plasma and brain insulin and calcium levels were elevated moderately following treatment with the lowest dose of dexamethasone. All doses of dexamethasone decreased brain superoxide dismutase and increased lactate dehydrogenase levels. No significant change in neural activity was observed. This study shows that activation of glucocorticoid receptors differentially affects different behavioral paradigms and provides evidence for a role for glucocorticoids in mediating insulin function in the brain.
糖皮质激素受体（GR）在多细胞动物中普遍表达。已有报道称其激活后会出现不同且相反的表型。本研究调查了雄性Wistar大鼠中GR刺激所特有的行为表型。四组大鼠中的每组大鼠接受以下一种处理：蒸馏水（对照）或腹腔注射三种剂量地塞米松之一（处理），持续7天。之后，大鼠接受Y迷宫、高架十字迷宫（EPM）、莫里斯水迷宫（MWM）和新物体识别（NOR）测试。在研究结束时，对动物进行麻醉并记录前额叶皮质的神经活动。通过心脏穿刺采集血液以评估血浆胰岛素和葡萄糖水平，并切除前额叶皮质以测定匀浆中胰岛素、氧化应激标志物和钙的水平。本研究表明，地塞米松处理显著降低了Y迷宫中的总交替次数和交替百分比，但对NOR测试中的物体识别、MWM中的长期和短期空间记忆或EPM中的焦虑样行为没有显著影响。用最低剂量地塞米松处理后，血浆和脑胰岛素及钙水平适度升高。所有剂量的地塞米松均降低了脑超氧化物歧化酶水平并增加了乳酸脱氢酶水平。未观察到神经活动有显著变化。本研究表明，糖皮质激素受体的激活对不同行为范式有不同影响，并为糖皮质激素在介导脑内胰岛素功能中的作用提供了证据。
