Large Molecular Weight Immunoreactive Corticotrophin-Releasing Hormone has Bioactivity on Superfused Ovine Pituitary Cells

Placental corticotrophin-releasing hormone, local effects and fetomaternal endocrinology

The human placenta produces corticotrophin-releasing hormone (CRH) in exponentially increasing amounts during pregnancy with peak levels during labour. CRH in human pregnancy appears to be involved in many aspects of pregnancy including placental bloodflow, placental prostaglandin production, myornetrial function, fetal pituitary and adrenal function and the maternal stress axis. Since fetal cortisol levels are associated with pulmonary development and maturity, placental CRH may have an indirect role in fetal development.Although the precise role of placental CRH in the regulation of gestational length and timing of parturition is unclear it appears to be involved in a placental clock. While glucocorticoids inhibit hypothalamic CRH production they stimulate CRH gene expression in the placenta.This difference may allow the fetal and maternal stress axes to influence this placental clock.Maternal CRH levels are elevated in many pathological conditions of pregnancy where fetal well-being is compromised, and in these situations it may act to maintain a stable intrauterine environment. Therefore, CRH appears to link placental function, maternal well-being, fetal well-being and fetal development to the duration of gestation and the timing of parturition.

Corticotropin releasing hormone: therapeutic implications and medicinal chemistry developments

Corticotropin releasing hormone (CRH, sometimes known as CRF) is an endogenous 41 amino acid peptide that has been implicated in the onset of pregnancy, the 'fight or flight' response, in addition to a large number of physiological disorders. Recently, medicinal chemists have developed a number of potent and selective compounds that show promise in a vast array of therapeutic uses. Herein we review the current status of research.

The effect of pre-eclampsia on human placental corticotrophin-releasing hormone content and processing

Prior studies have shown that levels of corticotrophin-releasing hormone (CRH) in the umbilical cord blood of infants born after pregnancies complicated by pre-eclampsia are significantly higher than fetal plasma CRH concentrations in uncomplicated pregnancies. In the present study we have measured CRH by radioimmunoassay in the placenta and fetal membranes from 13 pregnancies complicated by pre-eclampsia and compared them to 24 uncomplicated pregnancies. In addition we have investigated the effect of chronic intrauterine fetal stress on the processing of CRH in the placenta and fetal membranes. Placental CRH peptide content was significantly higher in the pregnancies complicated by pre-eclampsia, 12,900 +/- 4230 pg/g tissue, than in the uncomplicated pregnancies, 3130 +/- 430 pg/g of tissue (P < 0.01). Gel filtration of the homogenates of normal placenta revealed a major peak of CRH immunoactivity eluting in the same position as synthetic human CRH. A second smaller molecular weight peak of CRH-immunoactivity was also present and in both the amnion and the chorion, the CRH eluted in the position of the smaller molecular weight peak. In contrast, the bulk of the CRH immunoactivity in the placenta and fetal membranes obtained after pregnancies complicated by pre-eclampsia eluted in the position of intact synthetic human CRH. Thus, in pregnancy complicated by pre-eclampsia, both placental CRH release into fetal plasma and CRH peptide content is higher than in uncomplicated pregnancy.

Neuroendocrinology of the hypothalamo-pituitary-adrenal axis in pregnancy and the puerperium

Plasma cortisol, adrenocorticotrophic hormone (ACTH), beta-endorphin and corticotrophin releasing hormone or factor (CRF) all rise progressively as pregnancy advances, and fall postnatally. The placenta produces large amounts of CRF in the third trimester and this is released into the maternal circulation. Present evidence suggests that it stimulates the maternal pituitary to produce ACTH while desensitizing the maternal pituitary to further stimulation with CRF. Maternal control of ACTH production is retained, allowing a persistent response to stress and a diurnal rhythm, perhaps through the secretion of vasopressin. The placenta also produces pro-opiomelanocortin peptides; however, the nature of the fragments produced from the precursor differs from that formed in the anterior pituitary of the mother and the role of these fragments in the control of maternal adrenal function is unclear. These changes in the hypothalamo-pituitary-adrenal axis during pregnancy are associated with loss of the normal suppression of cortisol by dexamethasone and elevated basal levels of cortisol with preservation of a diurnal rhythm, features also found in some patients with endogenous depression. Several studies have suggested a relationship between alterations in maternal concentrations of cortisol and beta-endorphin and the development of postnatal mood disturbances.

Urinary corticotropin-releasing hormone immunoreactivity is elevated during human pregnancy

Plasma corticotropin-releasing hormone immunoreactivity (CRH IR) rises with gestational age in women. In order to investigate the physiological changes of the hormone in pregnant women's urine, CRH IR was measured by radioimmunoassay in urine collected over a 24-hour period, a blood sample and a subsequent single collection of urine after the 24-hour collection (spot urine). Plasma CRH IR in pregnant subjects, 8682.8 +/- 2063.0 pg CRH IR/ml plasma (mean +/- SEM, n = 25), was significantly higher than that in the non-pregnant controls (7.2 +/- 1.6 pg/ml, n = 5; separate t = 4.21, p = 0.0003, d.f. = 24). Similarly, pregnant women had higher spot urine CRH IR - 54.6 +/- 15.5 pg/mumol creatinine (Cr) versus 5.0 +/- 0.5 pg/mumol Cr (separate t = 3.20, p = 0.0038, d.f. = 24.0) - and 24-hour urine CRH IR - 13.7 +/- 1.2 pg/mumol Cr compared with 7.7 +/- 0.8 pg/mumol Cr (separate t = 4.28, p = 0.003, d.f. = 24.4) than the non-pregnant cohort. The difference between urinary excretion of CRH IR as estimated by 24-hour urine (13.7 +/- 1.2 pg/mumol Cr) and spot urine (54.6 +/- 15.5 pg/mumol Cr) indicated that CRH IR in 24-hour urine may be degraded during storage. The weak associations between plasma and 24-hour urine CRH IR of pregnant women (correlation coefficient r = 0.34, p greater than 0.1), and total 24-hour urine and spot urine CRH IR (r = 0.25, p less than 0.1) further indicate CRH degradation. Plasma and spot urinary CRH IR, however, were strongly correlated (r = 0.80, p = 0.001). The total CRH IR excreted as estimated from the spot urine value (0.5 +/- 0.1 micrograms/day) compared with the total filtered load of CRH IR in the pregnant group (1306.9 +/- 324.6 micrograms/day) showed that 99.97% of the filtered CRH IR was reabsorbed or metabolized by the kidneys. Acidic gel chromatography of spot and 24-hour urine samples showed a CRH IR peak at CRH41 standard elution position (Kd = 0.5), indicating that the molecular form in urine is similar to the 41-residue standard. Pregnancy-induced hypertension correlated positively with plasma CRH IR (r = 0.62, p less than 0.001) and spot urine CRH IR (r = 0.46, p less than 0.01), and negatively with parity (r = -0.60, p less than 0.001). Plasma CRH IR and parity also negatively correlated (r = -0.41, p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)