Guerreiro Pedro M, Rotllant Josep, Fuentes Juan, Power Deborah M, Canario Adelino V M
Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
Gen Comp Endocrinol. 2006 Sep 1;148(2):227-35. doi: 10.1016/j.ygcen.2006.03.004. Epub 2006 Apr 19.
In previous in vitro studies, we have shown that the N-terminal region of parathyroid hormone-related protein (PTHrP) can stimulate cortisol production in sea bream, Sparus auratus, interrenal tissue, possibly through a paracrine action. In the current study, the systemic interaction between cortisol and PTHrP was studied in vivo. Sustained elevated blood cortisol levels, induced either by cortisol injection or confinement stress, suppressed circulating PTHrP 6 and 24-fold, respectively, by comparison to control fish. Dexamethasone treatment reduced cortisol levels, prevented the decrease of plasma PTHrP observed in confined fish and raised plasma PTHrP levels in non-confined fish. In contrast, a single injection of (1-34) PTHrP caused a short-term (within 30 min and up to 2.5 h) decrease in plasma cortisol. The antagonistic effects between PTHrP and cortisol were substantiated by an overall (data pooled from all experiments) highly significant negative correlation (r0=-0.745, p<0.001, n=115) between the plasma levels of the two hormones. Although the underlying mechanism of the interaction still has to be determined, the high levels of PTHrP in circulation and the existence of systemic regulation favour the hypothesis that in fish PTHrP may act as an endocrine factor, although the gland that produces it still remains to be identified.
在之前的体外研究中，我们已经表明，甲状旁腺激素相关蛋白（PTHrP）的N端区域可能通过旁分泌作用刺激黑鲷（Sparus auratus）肾间组织中皮质醇的产生。在本研究中，我们在体内研究了皮质醇和PTHrP之间的系统相互作用。与对照鱼相比，通过注射皮质醇或施加禁闭应激诱导的持续升高的血皮质醇水平，分别使循环中的PTHrP水平降低了6倍和24倍。地塞米松处理降低了皮质醇水平，防止了禁闭鱼中观察到的血浆PTHrP水平下降，并提高了非禁闭鱼的血浆PTHrP水平。相反，单次注射（1-34）PTHrP导致血浆皮质醇短期（30分钟内直至2.5小时）下降。PTHrP和皮质醇之间的拮抗作用通过两种激素血浆水平之间总体上（来自所有实验的数据汇总）高度显著的负相关（r0 = -0.745，p <0.001，n = 115）得到证实。尽管相互作用的潜在机制仍有待确定，但循环中高水平的PTHrP和系统调节的存在支持了这样的假设，即PTHrP在鱼类中可能作为一种内分泌因子起作用，尽管产生它的腺体仍有待确定。
