Taylor A D, Loxley H D, Flower R J, Buckingham J C
Department of Pharmacology, Charing Cross and Westminster Medical School, London, UK.
Neuroendocrinology. 1995 Jul;62(1):19-31. doi: 10.1159/000126984.
Our recent studies suggest that lipocortin 1 (LC1), a potential mediator of the anti-inflammatory, antiproliferative and anti-fever actions of glucocorticoids in peripheral tissues, may also contribute to the powerful negative feedback actions of the steroids on the hypothalamo-pituitary-adrenal (HPA) axis. In the present study we have used (1) an in vitro model to examine the influence of a specific neutralizing monoclonal anti-LC1 antibody (anti-LC1 mAb) on the capacity of dexamethasone to suppress the cytokine-induced release of the 41-amino acid corticotropin-releasing factor (CRF-41) and arginine vasopressin (AVP) from the rat hypothalamus and (2) a passive immunization protocol to assess the contribution of LC1 to the inhibitory actions of dexamethasone on the HPA responses to immunological (i.p. injection of interleukin 1 beta, IL-1 beta) and surgical (laparotomy under ether anaesthesia) stress. In vitro, Il-1 alpha (0.2 ng/ml), IL-1 beta (0.5 ng/ml), IL-6 (10 ng/ml) and IL-8 (1 ng/ml) each caused significant increases in the release of immunoreactive (ir)-CRF-41 and ir-AVP from hypothalami removed from rats adrenalectomized 10-12 days before autopsy; these responses were readily inhibited by preincubation of the tissue with dexamethasone (10(-7) M). The inhibitory actions of the steroid were attenuated and, in many instances, abolished by inclusion in the medium of a monoclonal anti-LC1 antibody (LC1 mAb, diluted 1:15,000); an isotype-matched control antibody (antispectrin alpha+beta, diluted 1:15,000) was ineffective in this regard. IL-1 alpha (0.2 ng/ml), IL-1 beta (0.5 ng/ml) and IL-6 (10 ng/ml) also initiated similar increases in the release of CRF-41 and AVP from hypothalami from intact rats which were effectively blocked by dexamethasone (10(-7) M). However, although the inhibitory actions of the steroid on the pharmacologically evoked release of CRF-41 were specifically overcome by anti-LC1 mAb (diluted 1:15,000), the steroid blockade of AVP release was not. In vivo, rats pretreated with either a polyclonal anti-LC1 antibody (anti-LC1 pAb, 1 ml/day s.c. for 2 days) or a corresponding volume of a nonimmune sheep serum (NSS) responded to immunological (IL-1 beta, 3 micrograms/kg i.p.) or surgical (laparotomy under ether anaesthesia) trauma with significant increases in the serum ACTH and corticosterone concentrations. In the NSS-treated groups, dexamethasone (100 micrograms/kg), which had no effect on the prestress concentrations of ACTH and corticosterone in the blood, completely prevented the HPA responses to both IL-1 beta and laparotomy.(ABSTRACT TRUNCATED AT 400 WORDS)
我们最近的研究表明，脂皮质素1（LC1）作为糖皮质激素在外周组织中抗炎、抗增殖及退热作用的潜在介质，可能也参与了类固醇对下丘脑-垂体-肾上腺（HPA）轴强大的负反馈作用。在本研究中，我们采用了：（1）一种体外模型，以检测特异性中和单克隆抗LC1抗体（抗LC1 mAb）对地塞米松抑制细胞因子诱导的大鼠下丘脑释放41个氨基酸的促肾上腺皮质激素释放因子（CRF-41）和精氨酸加压素（AVP）能力的影响；（2）一种被动免疫方案，以评估LC1在地塞米松对免疫（腹腔注射白细胞介素1β，IL-1β）和手术（乙醚麻醉下剖腹术）应激的HPA反应抑制作用中的贡献。在体外，白细胞介素1α（0.2 ng/ml）、白细胞介素1β（0.5 ng/ml）、白细胞介素6（10 ng/ml）和白细胞介素8（1 ng/ml）均可使取自尸检前10 - 12天摘除肾上腺大鼠的下丘脑释放免疫反应性（ir）-CRF-41和ir-AVP显著增加；这些反应可通过用地塞米松（10⁻⁷ M）预孵育组织而轻易被抑制。类固醇的抑制作用减弱，并且在许多情况下，通过在培养基中加入单克隆抗LC1抗体（LC1 mAb，稀释1:15,000）而被消除；同种型匹配的对照抗体（抗血影蛋白α + β，稀释1:15,000）在这方面无效。白细胞介素1α（0.2 ng/ml）、白细胞介素1β（0.5 ng/ml）和白细胞介素6（10 ng/ml）也可使完整大鼠下丘脑释放CRF-41和AVP出现类似增加，这可被地塞米松（10⁻⁷ M）有效阻断。然而，尽管抗LC1 mAb（稀释1:15,000）可特异性克服类固醇对CRF-41药理诱导释放的抑制作用，但类固醇对AVP释放的阻断作用却未被克服。在体内，用多克隆抗LC1抗体（抗LC1 pAb，1 ml/天皮下注射，共2天）或相应体积的非免疫绵羊血清（NSS）预处理的大鼠，对免疫（IL-1β，3 μg/kg腹腔注射）或手术（乙醚麻醉下剖腹术）创伤的反应是血清促肾上腺皮质激素（ACTH）和皮质酮浓度显著增加。在NSS处理组中，地塞米松（100 μg/kg）对血液中应激前ACTH和皮质酮浓度无影响，但可完全阻止HPA对IL-1β和剖腹术的反应。（摘要截短于400字）
