Food-induced cortisol secretion is mediated by central alpha-1 adrenoceptor modulation of pituitary ACTH secretion.

Food ingestion stimulates cortisol secretion in man, but the mechanism of this effect is unknown. We have investigated the possible role of adrenoceptors in the mediation of this effect. Six normal males were given continuous 3 h i.v. infusions of normal saline, methoxamine (alpha-1 adrenoceptor agonist) and thymoxamine (alpha-1 adrenoceptor antagonist). Methoxamine enhanced and thymoxamine attenuated the ACTH and cortisol responses to a standard meal given 60 min after commencement of the infusion. The drugs had no effect on nutrient absorption. Four patients with recent onset of pituitary ACTH deficiency and normally responsive adrenal glands showed no ACTH or cortisol rises after the standard meal, demonstrating that postprandial cortisol secretion is mediated by pituitary rather than gut ACTH. Our previous investigations have demonstrated that alpha-1 adrenoceptors stimulate pituitary ACTH secretion in man by an action within the blood brain barrier. We therefore conclude that postprandial cortisol secretion is mediated by central stimulant alpha-1 adrenoceptors modulating pituitary ACTH secretion.

The radioimmunoassay of placental protein 5 and circulating levels in maternal blood in the third trimester of normal pregnancy.

A radioimmunoassay has been developed for placental protein 5 (PP5), a product of the human placenta. Circulating concentrations of PP5 were measured in the third trimester of normal pregnancy in 400 women. Concentrations of PP5 showed a skewed distribution and rose progressively to reach a plateau in the last four weeks of pregnancy. The development of this assay will permit studies on the potential clinical application of maternal PP5 levels during normal and abnormal pregnancy.

Is measurement of placental function and maternal weight worth while?

A prospective survey of 1029 women delivered during 1976 at St. Bartholomew's Hospital was undertaken to assess the predictive value of a variety of clinical, ultrasonic, and biochemical variables in the detection of high-risk pregnancies. The best antenatal predictors of fetal risk were severe pre-eclampsia, depressed maternal serum levels of human placental lactogen, low maternal weight at 32 weeks' gestation, and heavy smoking by the mother. 62% of the high-fetal risk group had one or more of these features, but so did 33% of the controls.

PIP: A prospective survey of 1029 women delivered during 1976 at St. Bartholomew's Hospital (London) was conducted in order to assess the predictive value of a variety of clinical, ultrasonic, and biochemical variables in the detection of high-risk pregnancies. When analysis was confined to maternal weight at 32 weeks, smoking, pre-eclampsia, maternal age, and human placental lactogen, 62% of the high-fetal-risk group was predicted accurately, and false-positive results occurred in 33% of the controls. The findings support the conclusion that routine placental function testing and maternal weighting are worthwhile. It is unlikely that the prediction of fetal risk can be improved by clinical indices, and the addition of other screening procedures such as ultrasonography in the 3rd trimester and monitoring of movement, breathing, and heart-rate patterns in the fetus might increase the prediction-rate.