Polk D H, Reviczky A, Lam R W, Fisher D A
Department of Pediatrics, King-Drew Medical Center, Los Angeles 90059.
Am J Physiol. 1991 Jan;260(1 Pt 1):E53-8. doi: 10.1152/ajpendo.1991.260.1.E53.
The ontogenesis of hypothalamic and extrahypothalamic thyrotropin-releasing hormone (TRH) and the effect of altered thyroid status on tissue TRH levels were studied in fetal sheep. At 62 days gestation (term = 145 days) TRH was detectable in serum and in hypothalamic, placental, and pancreatic tissues; pancreatic, placental, and serum levels exceeded hypothalamic levels two- to fivefold. Analysis of tissues obtained from 88-day gestation fetuses were comparable: TRH levels in placenta (54 +/- 15 pg/mg tissue protein), pancreas (34 +/- 5 pg/mg protein), and serum (93 +/- 9 pg/ml) exceeded those in hypothalamic extracts (15 +/- 9 pg/mg protein). By 120 days gestation, TRH values in the hypothalamus (610 +/- 52 pg/mg protein) exceeded those in extrahypothalamic sites; values were comparable at 140 days gestation. Fetal thyroidectomy resulted in a 2-fold elevation of hypothalamic TRH concentrations (1,030 +/- 139 vs. 522 +/- 29 pg/mg protein) and 2 to 20-fold elevations of TRH in the placenta (147 +/- 23 vs. 42 +/- 8 pg/mg protein), pancreas (195 +/- 11 vs. 29 +/- 7 pg/mg protein), duodenum (363 +/- 97 vs. 29 +/- 7 pg/mg protein), and serum (2,563 +/- 212 vs. 131 +/- 16 pg/ml). 3, 5, 3'-Triiodothyronine (T3) infusion in thyroidectomized fetuses resulted in elevated serum T3 values (480 +/- 80 ng/dl) and suppressed hypothalamic TRH (249 +/- 68 vs. 522 +/- 29 pg/mg protein) and serum TRH concentrations (30 +/- 4 vs. 131 +/- 156 pg/ml). Placental, pancreatic, and duodenal TRH concentrations in thyroidectomized T3-infused animals were below the level of detection of the assay (5 pg/mg tissue protein).(ABSTRACT TRUNCATED AT 250 WORDS)
在胎羊中研究了下丘脑和下丘脑外促甲状腺激素释放激素（TRH）的个体发生，以及甲状腺状态改变对组织TRH水平的影响。妊娠62天时（足月为145天），在血清、下丘脑、胎盘和胰腺组织中可检测到TRH；胰腺、胎盘和血清中的水平比下丘脑水平高出2至5倍。对妊娠88天胎儿的组织分析结果类似：胎盘（54±15 pg/mg组织蛋白）、胰腺（34±5 pg/mg蛋白）和血清（93±9 pg/ml）中的TRH水平超过下丘脑提取物中的水平（15±9 pg/mg蛋白）。到妊娠120天时，下丘脑的TRH值（610±52 pg/mg蛋白）超过下丘脑外部位的TRH值；在妊娠140天时两者相当。胎儿甲状腺切除术导致下丘脑TRH浓度升高2倍（分别为1030±139和522±29 pg/mg蛋白），胎盘（分别为147±23和42±8 pg/mg蛋白）、胰腺（分别为195±11和29±7 pg/mg蛋白）、十二指肠（分别为363±97和29±7 pg/mg蛋白）和血清（分别为2563±212和131±16 pg/ml）中的TRH升高2至20倍。对甲状腺切除的胎儿输注3,5,3'-三碘甲状腺原氨酸（T3）导致血清T3值升高（480±80 ng/dl），并抑制下丘脑TRH（分别为249±68和522±29 pg/mg蛋白）和血清TRH浓度（分别为30±4和131±156 pg/ml）。输注T3的甲状腺切除动物的胎盘、胰腺和十二指肠TRH浓度低于检测水平（5 pg/mg组织蛋白）。（摘要截短于250字）
