Kallaras C, Angelopoulos N, Apostolakis M, Bountzioukas S, Guiba-Tziampiri O, Kontoleon-Vakalopoulou H, Mavroudis K
Department of Experimental Physiology, Faculty of Medicine, Aristotelion University of Thessaloniki, Greece.
J Endocrinol Invest. 1998 Apr;21(4):200-10. doi: 10.1007/BF03347304.
In order to investigate the effects of centrally administered Atrial Natriuretic Peptide (ANP) on plasma ADH and corticosterone levels as well as on blood pressure and on heart rate, 20 male New Zealand White (NZW) rabbits were used. Measurements were made on restrained conscious animals one week after the implantation of an indwelling intracerebroventricular (i.c.v.) cannula and two indwelling intravascular catheters (intracarotid and intrajugular). Animals were classified into two main groups, those with water available ad libitum ("euhydrated" group) and those who were dehydrated for 24h ("dehydrated" group) before blood pressure and heart rate recordings and blood sampling for hormonal determination. Each group's individuals were divided into two subgroups of five animals each. Blood samples were collected at 0 min (control) and 30; 60, 90, 120 min following i.c.v. administration of 25 microliters of either artificial cerebrospinal fluid (aCSF) (subgroups "aCSF") or human (h) ANP (1 microgram) in aCSF (25 microliters) (subgroups "hANP"). Blood pressure and heart rate were also recorded at the same times. Plasma ADH and corticosterone concentrations were determined by RIA. The results were analysed by ANOVA. Blood pressure and heart rate values were unaffected by water deprivation or by ANP administration. Mean plasma corticosterone levels at all times (30-120 min) were significantly higher (p < 0.001) than at 0 min time. Plasma corticosterone levels in the "dehydrated + aCSF" group were significantly higher (p < 0.05) than in each of the other groups ("dehydrated + hANP", "euhydrated + aCSF", "euhydrated + hANP"). Plasma corticosterone levels in each of those other groups did not differ significantly from one another. Dehydration resulted in an increase in ADH levels (p < 0.0001) and i.c.v. administration of hANP prevented (p < 0.05) in "dehydrated + hANP" experimental group, the increase in ADH levels observed in the control "dehydrated + aCSF" group from 90 to 120 min. The increase of corticosterone and ADH in the control dehydrated groups could possibly be due to the combined stress stimulus of dehydration and restriction in the restrain box. These results indicate that centrally administered ANP, at the concentration achieved in the present study, neither affects blood pressure and heart rate in conscious restrained euhydrated and 24h-dehydrated NZW rabbits nor decreases the ADH and corticosterone response to dehydration, but does apparently modulate ADH and corticosterone responses to other stimuli in the dehydrated state. In conclusion, the results of this study confirm that brain ANP may have an inhibitory effect on stimulated ADH and corticosterone release.
为了研究脑室内注射心房利钠肽（ANP）对血浆抗利尿激素（ADH）和皮质酮水平以及血压和心率的影响，选用了20只雄性新西兰白兔（NZW）。在植入留置脑室内（i.c.v.）套管和两根留置血管内导管（颈内和颈外静脉）一周后，对清醒且受约束的动物进行测量。动物被分为两个主要组，一组可随意饮水（“正常水合”组），另一组在记录血压、心率以及采集血样进行激素测定之前脱水24小时（“脱水”组）。每组个体又分为两个亚组，每组五只动物。在脑室内注射25微升人工脑脊液（aCSF）（“aCSF”亚组）或含1微克人（h）ANP的aCSF（25微升）（“hANP”亚组）后的0分钟（对照）、30、60、90、120分钟采集血样。同时记录血压和心率。采用放射免疫分析法（RIA）测定血浆ADH和皮质酮浓度。结果采用方差分析（ANOVA）进行分析。血压和心率值不受缺水或ANP注射的影响。所有时间点（30 - 120分钟）的平均血浆皮质酮水平均显著高于0分钟时（p < 0.001）。“脱水 + aCSF”组的血浆皮质酮水平显著高于其他各组（“脱水 + hANP”、“正常水合 + aCSF”、“正常水合 + hANP”）（p < 0.05）。其他各组的血浆皮质酮水平彼此之间无显著差异。脱水导致ADH水平升高（p < 0.0001），在“脱水 + hANP”实验组中，脑室内注射hANP可预防（p < 0.05）在对照“脱水 + aCSF”组中观察到的90至120分钟ADH水平的升高。对照脱水组中皮质酮和ADH的升高可能是由于脱水和在约束箱中受限的联合应激刺激所致。这些结果表明，在本研究达到的浓度下，脑室内注射ANP既不影响清醒且受约束的正常水合和24小时脱水的NZW兔的血压和心率，也不降低ADH和皮质酮对脱水的反应，但在脱水状态下确实明显调节ADH和皮质酮对其他刺激的反应。总之，本研究结果证实脑内ANP可能对刺激的ADH和皮质酮释放具有抑制作用。
