Neuroscience Disease Area, Novartis Institutes for Biomedical Research, Novartis Pharma, Basel CH-4002, Switzerland.
Neuropharmacology. 2011 Feb-Mar;60(2-3):318-27. doi: 10.1016/j.neuropharm.2010.09.015. Epub 2010 Sep 22.
Corticotropin releasing factor (CRF) is a major mediator of central and peripheral responses to environmental stressors, and antagonism of its receptors (CRF-R1, -R2) is an active area of pharmacotherapeutic research for stress-related disorders. Stress responses include CRF activation of the hypothalamus-pituitary-adrenal axis and behavioural inhibition. Valid in vivo models for the study of these neuro-endocrine and -behavioural CRF pathways and their central-peripheral antagonism are important. The aims of this study in C57BL/6 mice were to describe the acute effects of intracerebroventricular (ICV) CRF using plasma ACTH-CORT titres and locomotor activity as readouts, and to study the impact on these readouts of central versus peripheral pre-treatment with the CRF-R1/2 antagonist, astressin. The following experiments were performed: Effects of (i) serial blood sampling (SBS) per se, (ii) physical confinement+SBS, (iii) ICV saline infusion+SBS, on plasma titres of ACTH-CORT. (iv) Effects of ICV or IP CRF infusion on plasma ACTH-CORT. (v) Effects of ICV CRF on plasma CRF. (vi) Effects of ICV or IP astressin on ICV or IP CRF-stimulated plasma CORT. (vii) Effects of ICV or IP astressin on ICV CRF-induced locomotor inactivity. Main findings were: (i)-(ii) Serial blood sampling per se and physical confinement+SBS led to similar, mild increases in plasma ACTH-CORT. (iii) ICV saline infusion led to a marked increase in plasma ACTH, possibly due to assay crossreactivity with "washed out" pituitary peptides, and a mild increase in plasma CORT. (iv) ICV CRF (0.001-1μg) induced no further increase in plasma ACTH versus vehicle, and induced dose-dependent increased plasma CORT. 1μg ICV CRF also reduced locomotor activity. (v) ICV CRF-induced dose-dependent increased plasma CRF. (vi) ICV astressin failed to block ICV CRF-induced increased plasma CORT, whereas IP astressin did do so. (vii) ICV CRF-induced locomotor inactivity was blocked by ICV astressin, but not by IP astressin. Therefore, ICV CRF-induced a dose-dependent increase in plasma CORT via a peripheral pathway and a reduction in locomotion via a central pathway, indicated by the double dissociation in the ability of astressin to antagonize these effects relative to its route of administration, IP or ICV, respectively. The preparation described here could be readily used to provide initial indications on the central and peripheral activity of CRF-R antagonists, including pharmacokinetics following peripheral administration.
促肾上腺皮质释放因子（CRF）是中央和外周对应激源反应的主要介质，其受体（CRF-R1、-R2）的拮抗作用是应激相关疾病药物治疗研究的一个活跃领域。应激反应包括 CRF 激活下丘脑-垂体-肾上腺轴和行为抑制。研究这些神经内分泌和行为 CRF 途径及其中央-外周拮抗作用的有效体内模型非常重要。本研究在 C57BL/6 小鼠中，旨在描述使用血浆 ACTH-CORT 浓度和运动活性作为读出物的脑室内（ICV）CRF 的急性效应，并研究中央与外周预处理对 CRF-R1/2 拮抗剂 astressin 的影响。进行了以下实验：（i）连续采血（SBS）本身，（ii）身体约束+SBS，（iii）ICV 盐水输注+SBS，对血浆 ACTH-CORT 浓度的影响。（iv）ICV 或 IP CRF 输注对血浆 ACTH-CORT 的影响。（v）ICV CRF 对血浆 CRF 的影响。（vi）ICV 或 IP astressin 对 ICV 或 IP CRF 刺激的血浆 CORT 的影响。（vii）ICV 或 IP astressin 对 ICV CRF 诱导的运动不活动的影响。主要发现是：（i）-（ii）连续采血本身和身体约束+SBS 导致血浆 ACTH-CORT 相似的轻度增加。（iii）ICV 盐水输注导致 ACTH 明显增加，可能是由于与“冲洗出”垂体肽的测定交叉反应，以及 CORT 轻度增加。（iv）ICV CRF（0.001-1μg）与载体相比，未引起血浆 ACTH 的进一步增加，并且诱导剂量依赖性增加的血浆 CORT。1μg ICV CRF 还降低了运动活性。（v）ICV CRF 诱导的剂量依赖性增加血浆 CRF。（vi）ICV astressin 未能阻断 ICV CRF 诱导的血浆 CORT 增加，而 IP astressin 则可以。（vii）ICV CRF 诱导的运动不活动被 ICV astressin 阻断，但不能被 IP astressin 阻断。因此，ICV CRF 通过外周途径诱导血浆 CORT 的剂量依赖性增加，通过中央途径减少运动，这表明 astressin 拮抗这些作用的能力相对于其给药途径（IP 或 ICV）存在双重分离。这里描述的制剂可以很容易地用于提供关于 CRF-R 拮抗剂的中央和外周活性的初步指示，包括外周给药后的药代动力学。
