Twenty-four hour rhythms of hypothalamic corticotropin-releasing hormone, thyrotropin-releasing hormone, growth hormone-releasing hormone and somatostatin in rats injected with Freund's adjuvant.

A I Esquifino, L Selgas, E Vara, A Arce, D P Cardinali
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引用次数: 15

Abstract

The effect of Freund's adjuvant injection on 24-hour variation of hypothalamic corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), GH-releasing hormone (GRH) and somatostatin levels was examined in adult rats kept under light between 0800 and 2000 h daily. Groups of rats receiving Freund's complete adjuvant or its vehicle 3 days before sacrifice were killed at six different time intervals throughout a 24-hour cycle. In the median eminence, adjuvant vehicle-injected rats exhibited significant 24-hour variations for the four hormones examined, with maxima at noon. These 24-hour rhythms were inhibited or suppressed by Freund's adjuvant injection. In the anterior hypothalamus of adjuvant vehicle-treated rats, CRH content peaked at 1600 h, while two peaks were found for TRH and GRH levels, i.e., at 2400-0400 h and 1600 h. Freund's adjuvant injection suppressed 24-hour rhythm of anterior hypothalamic CRH, TRH and GRH content and uncovered a peak in anterior hypothalamic somatostatin levels at 0400 h. In the medial hypothalamus of adjuvant vehicle-treated rats, significant 24-hour variations were detectable for TRH (peaks at 1600 and 2400 h) and somatostatin (peak at 2400 h) which disappeared after Freund's adjuvant injection. In the posterior hypothalamus of adjuvant vehicle-treated rats, two peaks were apparent for CRH, TRH and somatostatin levels, i.e. at 1600 h and 2400-0400 h, this hormonal profile remaining unmodified after Freund's adjuvant administration. The administration of the immunosuppressant drug cyclosporine (5 mg/kg, 5 days) impaired the depressing effect of Freund's adjuvant injection on CRH, TRH and somatostatin content in median eminence, but not that on GRH. In the anterior hypothalamus, cyclosporine generally prevented the effect of immunization on hormone levels an revealed a second maximum in TRH at 0400 h. Cyclosporine also restored 24-hour variations in TRH and somatostatin levels of medial hypothalamus of Freund's adjuvant-injected rats but was unable to modify them in the posterior hypothalamus. The results further support the existence of a significant effect of immune-mediated inflammatory response at an early phase after Freund's adjuvant injection on hypothalamic levels which was partially sensitive to immunosuppression by cyclosporine.

注射弗氏佐剂大鼠下丘脑促肾上腺皮质激素释放激素、促甲状腺激素释放激素、生长激素释放激素和生长抑素的24小时节律。
研究了弗氏佐剂注射对成年大鼠下丘脑促肾上腺皮质激素释放激素(CRH)、促甲状腺激素释放激素(TRH)、gh释放激素(GRH)和生长抑素水平24小时变化的影响。各组大鼠在献祭前3天接受Freund完全佐剂或其载体,在24小时周期内以六个不同的时间间隔杀死。在正中隆起,佐剂注射大鼠的四种激素在24小时内表现出显著的变化,在中午达到最大值。这些24小时节律被弗洛伊德佐剂注射抑制或抑制。佐剂处理大鼠下丘脑前侧CRH含量在1600 h达到峰值,TRH和GRH含量在2400-0400 h和1600 h出现两个峰值。Freund佐剂注射抑制下丘脑前侧CRH、TRH和GRH含量的24小时节律,并在0400 h发现下丘脑前侧生长抑素水平出现峰值。TRH(1600和2400 h)和生长抑素(2400 h)在注射弗氏佐剂后消失,24小时变化显著。在佐剂处理的大鼠下丘脑后部,CRH、TRH和生长抑素水平在1600 h和2400-0400 h出现两个明显的峰值,这一激素谱在给予Freund佐剂后保持不变。免疫抑制药物环孢素(5 mg/kg, 5 d)可削弱弗氏佐剂注射对中隆起CRH、TRH和生长抑素含量的抑制作用,但对GRH没有影响。在下丘脑前部,环孢素通常阻止免疫对激素水平的影响,并在0400 h时显示出TRH的第二次最大值。环孢素还恢复了注射了Freund佐剂的大鼠下丘脑内侧TRH和生长抑素水平的24小时变化,但无法改变下丘脑后部的TRH和生长抑素水平。这些结果进一步支持了在注射弗氏佐剂后早期免疫介导的炎症反应对下丘脑水平的显著影响,下丘脑对环孢素免疫抑制部分敏感。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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