Brooks A N
MRC Reproductive Biology Unit, Edinburgh, Scotland.
J Dev Physiol. 1992 Oct;18(4):173-7.
The hypothesis that prostaglandins stimulate fetal adrenocortical activity via a central site of action within the fetal brain was tested in chronically catheterized fetal sheep. At day 120 gestation (term = 145 days) fetal sheep were surgically prepared with catheters in the lateral cerebral ventricle, jugular vein and carotid artery and experiments began five days later. Intravenous (i.v.) infusion of prostaglandin E2 (30 or 120 micrograms.h-1) caused a significant dose-related increase in fetal plasma concentrations of ACTH. Despite this increase in ACTH, cortisol was only stimulated after the highest dose of prostaglandin E2. Intracerebroventricular (i.c.v.) infusion of PGE2 (30 micrograms.h-1) also stimulated ACTH secretion although the peak response was delayed and considerably less compared with the same dose administered intravenously. Prostaglandin F2 alpha administered i.v. or i.c.v. had no effect on circulating concentrations of either ACTH or cortisol. These data provide evidence that prostaglandin E2 can stimulate fetal ACTH secretion by acting in the fetal brain. Furthermore, the greater release of ACTH after i.v. compared with i.c.v. prostaglandin E2 suggests that a site of action other than the brain, such as the pituitary gland, may also be important. These results provide further evidence that during late gestation circulating prostaglandins can act to stimulate fetal pituitary-adrenal maturation.
在长期插管的胎羊中，对前列腺素通过胎儿脑内的中枢作用位点刺激胎儿肾上腺皮质活动这一假说进行了验证。在妊娠120天（足月为145天）时，给胎羊进行手术，在其侧脑室、颈静脉和颈动脉中插入导管，五天后开始实验。静脉注射前列腺素E2（30或120微克·小时⁻¹）导致胎儿血浆促肾上腺皮质激素（ACTH）浓度出现显著的剂量相关增加。尽管ACTH有这种增加，但仅在给予最高剂量的前列腺素E2后皮质醇才受到刺激。脑室内注射前列腺素E2（30微克·小时⁻¹）也刺激了ACTH分泌，不过与静脉注射相同剂量相比，峰值反应延迟且程度要小得多。静脉内或脑室内注射前列腺素F2α对ACTH或皮质醇的循环浓度均无影响。这些数据证明前列腺素E2可通过作用于胎儿脑来刺激胎儿ACTH分泌。此外，与脑室内注射前列腺素E2相比，静脉注射后ACTH释放更多，这表明除脑之外的作用位点（如垂体）可能也很重要。这些结果进一步证明，在妊娠后期，循环中的前列腺素可起到刺激胎儿垂体 - 肾上腺成熟的作用。
