Study on maternal, fetal, and amniotic human prolactin at term

Relationship between the amniotic fluid prolactin level at early second trimester and pregnancy outcome

Aim: The aim of this study was to determine whether early second trimester amniotic fluid prolactin level were associated with pregnancy outcome. Material and Method: This study included 125 women who underwent amniocentesis for variable indications. Healthy subjects with no history of drug use were included in this study. The gestational age was determined by ultrasonic examination before 10 weeks in all cases. Amniotic fluid specimens were taken while performing amniocentesis for other indications. Amniotic fluid was collected by transabdominal amniocentesis. Amniotic fluid prolactin concentrations were utilized to predict pregnancy complication among women who underwent amniocentesis due to the variable indications. Results: Among all study population, pregnancy was unremarkable in 102 (81.6%) cases, on the other hand, most common fetal abnormality was found to be the fetal hydrops fetalis and the second most commonly encountered fetal anomaly was trisomy, intrauterine growth restriction and intrauterine fetal demise. All study population was divided into two groups as complicated (n=23) and uncomplicated (n=102) pregnancies. Amniotic fluid prolactin concentration did not have any predictive value for complicated pregnancies (AUC=0.479). Conclusion: Our data showed; there is no relationship between early second trimester amniotic fluid prolactin level and pregnancy outcome.

Hormone replacement therapy and changes on pituitary function

The aim of this study is to know how the pituitary function is affected by several delivery systems of estrogen replacement therapy. 116 menopausal women (54 natural and 62 surgical) were placed into three groups that received replacement therapy and in one control group. We determined prolactine (PRL), gonadotropins and 17 beta-estradiol (E2). We found a decrease in gonadotropin levels in treated patients with a natural menopause, and an increase in gonadotropin levels in the groups treated with conjugated estrogens in surgical menopausal women. 17 beta-E2 was found to be increased in all treated groups, mainly in the continuous therapy group (P less than 0.05). PRL was found to be decreased in patients treated with conjugated estrogens (oophorectomized and not oophorectomized) (P less than 0.05). Although these differences can not be attributed to the presence of the ovaries, we think that they may be the result of the treatment.

Prolactin and cortisol levels during spontaneous and oxytocin induced labour and the effect of meperidine

The effect of stress during labour on the plasma concentration of prolactin and cortisol was studied in 30 healthy multiparous women. The plasma concentrations of prolactin and cortisol were measured by radioimmunoassay during oxytocin induced labour, spontaneous labour, delivery and postpartum 24 h. The parturients were divided into three groups. The first group was given oxytocin for the induction of labour, the second group was also given oxytocin for the induction of labour and 100 mg of meperidine was administered intramuscularly for relief of pain and anxiety, and the third group was the control group with normal parturients who did not receive any medication. The prolactin levels showed a fall during labour in all the groups, but this fall was more marked in the first group where stress was evident. The concentrations of cortisol tended to increase during labour and reached a maximum at delivery in all three groups but in the meperidine group this level was significantly lower than the first and control groups. These results give further support to the hypothesis that maternal stress leads to a reduced concentration of prolactin and increased concentration of cortisol whereas relief of pain and maternal anxiety with meperidine lessens both effects.

Cervical mucus prolactin levels in normal fertile and infertile women

Cervical mucus and serum samples were obtained from 42 anovular women and 20 normal ovular fertile women (controls) for the determination of prolactin concentration by a solid phase radioimmunoassay. The former group was subgrouped into 14 galactorrhoeic (9 with oligohypomenorrhea and 5 with amenorrhea) and 28 non-galactorrhoeic (19 with oligohypomenorrhea and 9 with amenorrhea). The level of prolactin in cervical mucus of normally menstruating women was significantly higher than that of serum at P less than 0.0125 (11.68 +/- 0.77 ng/ml and 16.09 +/- 1.65 ng/ml, mean +/- SE, respectively). Serum prolactin level in galactorrhoeic amenorrhea cases was 8.2 times that of controls, while cervical mucus prolactin amounted to 32 times its control value. The rise of cervical mucus prolactin in cases of galactorrhea oligohypomenorrhea was 21 times its control value which is markedly higher than that of serum (1.9 times). The average rise of serum prolactin in the whole group of galactorrhea with abnormal menstrual function was about 4 times the control value, while the average rise of cervical mucus prolactin was about 41 times the corresponding control value. In the cases of galactorrhea with menstrual dysfunction, serum prolactin level may be normal in 50% of cases, while cervical mucus prolactin is strikingly elevated in 100% of cases. The possibility of pituitary adenoma should be considered if the level of serum or cervical mucus prolactin exceeds 100 ng/ml and 600 ng/ml respectively. The possible physiological role of cervical mucus prolactin and its source are discussed.

Vaginal fluid prolactin: a reliable marker for the diagnosis of prematurely ruptured membranes. Comparison with vaginal fluid alpha-fetoprotein and placental lactogen

The aim of this study is the evaluation of the reliability of vaginal fluid (VF) prolactin (PRL) for detecting prematurely ruptured membranes (PROM) and the comparison of this marker with vaginal fluid alpha-fetoprotein (AFP) and placental lactogen (HPL). In 21 pregnant women with recent or prolonged PROM from 20 to 41 weeks' gestation, in whom intact membranes were never found subsequently VF- and MS-PRL, -AFP and -HPL were measured by enzyme immunoassays, which are sensitive and very rapid. The same markers were also measured in MS, VF and urine samples (U) in 12 pregnant women of the same gestational age, without PROM, in whom the membranes were ruptured later during labor. In PROM, independently of prematurity and duration of PROM VF-PRL levels were significantly higher (2-10-fold) than the paired MS-PRL (p less than 0.0001) and ranged from 130 to 2315 ng/ml. In contrast, VF-PRL and urine PRL concentrations in pregnancies without PROM were very low or undetectable (range: 0-5 ng/ml and 0.15-1 ng/ml, respectively). Vaginal fluid AFP values in PROM from 20th to the 33rd week of pregnancy were significantly higher (5-50-fold) than the paired MS-AFP (p less than 0.01) and ranged from 103 to 5500 ng/ml. In PROM after the 33rd week of pregnancy, VF-AFP values were either lower (1/3), or equal to, or even higher (up to 2-fold) than MS-PRL. On the contrary in pregnancies with intact membranes, VF-AFP were always less than 9 ng/ml and urine AFP was undetectable (range: 0.2-1.1 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and characterization of cyclo(His-Pro)-like immunoreactivity in amniotic fluid

Amniotic fluid (AF) from 25 term pregnancies was analyzed for cyclo(His-Pro)-like immunoreactivity (CHP-LI). CHP-LI was detected in all AF samples and was indistinguishable from synthetic CHP by immunoidentity, by gel chromatography on Sephadex G-25, and by high pressure liquid chromatography. The mean concentration of CHP-LI in AF was 13,622 +/- 1288 pg/ml (+/- SE) and concentrations were not altered by maternal labor. Plasma concentrations of CHP-LI were similar in 4 pregnant and 4 control subjects [2260 +/- 432 pg/ml vs. 2162 +/- 419 pg/ml (+/- SE), respectively]. We conclude that 1) CHP-LI is readily detected in AF from term pregnancies and is indistinguishable from synthetic CHP, and 2) concentrations of CHP-LI in human AF are significantly higher than concentrations of maternal plasma CHP-LI, suggesting CHP AF originates by mechanisms other than diffusion from maternal plasma.

Role of placental lactogen and prolactin in human pregnancy

In summary, studies from our and other laboratories strongly suggest that placental lactogen has direct effects on fetal growth and metabolism as well as on maternal metabolism. Prolactin may be important in the regulation of water and ion transport across the amnion, the production of surfactant by the fetal lung, and the immune response during pregnancy. A summary of the postulated effects of placental lactogen on maternal and fetal physiology is depicted in Figure 9 and a summary of the postulated effects of prolactin during pregnancy is shown in Table 6. Undoubtedly, future studies of the physiology of placental lactogen and prolactin will uncover new functions for these hormones during gestation.

Immunohistochemical identification of prolactin and 24K protein in secretory endometrium

Inadequate endometrial differentiation is a cause of infertility and recurrent pregnancy loss. Diagnostic histologic dating criteria may be supplemented by the immunohistochemical identification of protein markers in late secretory endometrium. Late secretory endometrium has been shown to contain prolactin. The authors report the immunohistochemical localization of prolactin and 24K protein in late secretory endometrium using monoclonal antisera and the dinitrophenyl hapten sandwich-staining technique. The appearance of these proteins in decidualized stromal cells of late secretory endometrium may provide a more specific indicator of endometrial development and differentiation, if their late appearance or absence can be correlated with pregnancy wastage.

Immunohistochemical localization of follicle-stimulating hormone, luteinizing hormone, growth hormone, adrenocorticotrophic hormone and prolactin in the human placenta

The sites of localization of luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), adrenocorticotrophic hormone (ACTH) and prolactin (PRL) within placental tissues have been studied by an immunoperoxidase technique. The syncytiotrophoblast is the sole significant site of localization of LH, FSH, GH and ACTH; PRL is found both in syncytiotrophoblast and in decidual cells. It is highly probable that the sites of localization of these peptide hormones represents their sites of synthesis in the placenta and thus that the syncytiotrophoblast is the sole site of synthesis of LH, FSH, LH and ACTH. PRL appears to be synthesized both in syncytiotrophoblast and decidua, but the latter is probably not the major site of synthesis of this hormone. Whether these placental peptide hormones have any physiological role to play during pregnancy or whether the placental capacity to synthesize such hormones is an atavistic phenomenon of no functional importance is currently a moot point.

Prolactin levels in hypothyroid and euthyroid infants during the first week of life

A radioimmunoassay (RIA) procedure was devised for the estimation of PRL in eluates of dried whole blood from filter paper. Levels of PRL were measured in newborn blood obtained during the first week of life from 530 infants of normal birthweight (greater than 2500 g) with normal T4 values, 114 infants of normal birthweight with low T4 values (T4 less than 6.0 micrograms/dl), 47 infants with congenital hypothyroidism, 57 infants of low birthweight (less than 2500 g) with normal T4 values, and 114 infants of low birthweight with low T4 values. Examination of PRL concentrations among comparably aged infants from the various groups revealed that the mean PRL values of the hypothyroid group were consistently greater than those of any of the other groups of infants regardless of the mean T4 levels. With the exception of the hypothyroid infants, the groups with both the lowest mean T4 concentrations and mean body weights also had the lowest mean PRL values.

Prolactin bioactivity following decidual synthesis and transport by amniochorion

Current evidence suggests that high concentrations of prolactin in human amniotic fluid result from the transport of human decidual prolactin across reflected amniochorion. In this study, tritiated leucine placed on the isolated maternal side of amniochorion with adherent decidua was incorporated into newly synthesized tritiated human decidual prolactin. Identification of tritiated decidual prolactin on the fetal side of suspended membranes was confirmed within 4 hours of incubation. A heterologous species of human decidual prolactin identified on the maternal side of membranes was also detectable on the fetal side, and its bioactivity was found to be equivalent in both fetal and maternal chambers separated by amniochorion. These results confirm the de novo synthesis of human decidual prolactin and transport by amniochorion to the fetal side. Subsequent to transport, the biologic activity of human decidual prolactin is retained. Thus concentrations and biologic activity of amniotic-fluid prolactin can be accounted for by the transport of newly synthesized human decidual prolactin by the reflected amniochorion.

Studies on the nature of prolactin-like immunoreactivity in bromelin-treated cervical mucus

Prolactin has been reported to be present in cervical mucus at concentrations higher than those found in blood. Our initial findings appeared to confirm this and the material fulfilled criteria of validity generally applied when an immunoassay is employed on a new biological matrix, i.e. parallelism and chromatographic identity. Further experiments demonstrated that prolactin concentrations in cervical mucus were less than 40 mU/L and the prolactin-like immunoreactivity originally detected was due to the action of the enzyme bromelin which was used to liquefy the mucus. Bromelin has a similar molecular weight to prolactin and appeared to digest prolactin tracer and reduce its ability to bind antiserum in a manner paralleling the effect of adding pituitary prolactin.

Prolactin binding in the developing rat fetal liver

The binding of prolactin by fetal rat liver cell membrane fractions from 17 to 21 days gestation was studied. Particulate liver membranes were prepared in Dulbecco's Phosphate Buffered Saline (PBS) by ultracentrifugation and incubated at 22 degrees C for 16 hours with [125I] iodo-human growth hormone (hGH). Non-specific binding was assessed by parallel incubations in the presence of a 2000-fold excess ovine prolactin. Specific prolactin binding sites were detected only at 21 days gestation (2932 +/- 401 cpm/mg protein) in freshly prepared membranes. On freezing at -20 degrees C for 24 to 48 hours, the membranes of 20 days gestation animals were able to specifically bind prolactin (1295 +/- 239 cpm/mg protein). Freezing led to a 45 +/- 7% increase (4270 +/- 701 cpm/mg protein) in prolactin binding at 21 days gestation. No hormonal binding was detected from 17 through 19 days gestation in either fresh or freeze-thawed membranes. Scatchard analysis revealed a high affinity binding site with a Ka of approximately 1.4 X 10(8)M-1 in both fresh and freeze-thawed membrane preparations. The data show that 1) prolactin receptors appear in liver only during late fetal life and that 2) freezing of membranes may unmask binding sites that are initially unavailable to specifically bind prolactin.

The clinical significance of endometrial prolactin

Prolactin (PRL) is produced not only by the anterior pituitary gland but also by human endometrium. That decidual stromal cells secrete PRL from day 22 of the menstrual cycle is demonstrated by: 1) nett accumulation of PRL during in vitro culture; 2) PRL accumulation is prevented by inhibitors of protein synthesis; and 3) identification of PRL mRNA within endometrial decidua. Endometrial PRL is biologically and immunologically equipotent with pituitary PRL and its amino acid sequence is very similar. In human pregnancy, decidual PRL binds to receptors on the fetal chorion and amnion and thereby passes into amniotic fluid in high concentration. Three putative functions of uterine PRL are suggested from current studies: a) a PRL receptor defect is present in the chorion laeve of patients with pregnancies complicated by chronic polyhydramnios and this deficiency in chorionic receptors for endometrial PRL may result in the development of excessive amniotic fluid; b) decidual PRL may modulate prostaglandin synthesis not only within the endometrium prior to menstruation, but also within the chorion and amnion to allow labour to proceed in a timely manner; and c) amniotic fluid PRL may pass into the fetal tracheo-bronchial system to promote surfactant production. Unlike pituitary PRL with distant target organs, decidual PRL appears to have paracrine or cybernetic functions in the human uterus, placental membranes and the fetus.

Study on maternal, fetal and amniotic prolactin in gestational diabetic women, at term

In order to determine whether prolactin secretion was affected in diabetic pregnancy, maternal, fetal and amniotic fluid prolactin (PRL) concentrations were measured in gestational non treated diabetic women at parturition. Amniotic fluid PRL levels, though higher than those in maternal and fetal serum, were significantly lower than those of the controls (p less than 0.005); no case of respiratory distress syndrome or congenital malformation was found at birth.

Size heterogeneity of immunoreactive prolactin in hyperprolactinaemic serum

Thirty-five samples of serum with levels of immunoreactive prolactin greater than 500 mu/l have been fractionated by gel filtration. In samples from seven normal subjects with elevated prolactin levels following TRH or insulin stimulation and samples from twelve patients with prolactin levels greater than 1500 mu/l, over 8% of the immunoreactive material eluted in the position of native or 'little' prolactin. In eleven out of sixteen samples containing 500 to 1500 mu/l the proportion of 'little' prolactin was less than 80% and more than 20% eluted as 'big-big' prolactin. It appears therefore that patients with moderately elevated levels of immunoreactive prolactin may not have genuine hyperprolactinaemia.

Unusual heterogeneity of circulating prolactin in an acromegalic

Plasma from a 69-year-old acromegalic woman with hyperprolactinemia (350-570 ng/ml) was chromatographed on dextran gel. Three components of immunoactive prolactin were observed. Component I eluted with an apparent molecular weight (MWapp) of greater than 100,000, Component II with MWapp of 45,000 and Component III with MWapp of 21,500 daltons (indistinguishable from monomeric pituitary prolactin). Components I and II comprised more than 70% of the total circulating prolactin. All components had similar activities in immunoassays and in receptor assays. Components II and III maintained their elution positions on re-chromatography. Component I whether frozen or stored at 4 C eluted in the position of Component II on rechromatography, suggesting that Component I is a loosely-bound oligomer of Components II or III, or Component III loosely-bound to another constituent of plasma. The gel chromatography pattern for immunoactive growth hormone was indistinguishable from that of other acromegalic patients.

Amniotic fluid prolactin levels and lecithin/sphingomyelin ratios during the third trimester of human gestation

Prolactin levels in amniotic fluid during the third trimester of human pregnancy showed a wide range of values. There was no apparent correlation between amniotic fluid prolactin concentrations (AF PRL) and lecithin/sphingomyelin (L/S) ratios nor was there a prolactin concentration associated with a mature L/S ratio. There was no correlation between AF PRL concentration and estimated gestational age or neonatal birth weight. In patients with diabetes mellitus (White Classes A to C), AF PRL were higher prior to 37 weeks, or when the L/S ratio was less than 2, than after 37 weeks, or when the L/S ratio was greater than 2.

Decidual production of prolactin in late gestation: further evidence for a decidual source of amniotic fluid prolactin

The capacity of human decidual tissue to synthesize prolactin de novo throughout late gestation was investigated and correlated with the levels of prolactin (PRL) in amniotic fluid. Maximal concentrations of PRL in both amniotic fluid and samples of decidua were found prior to the thirtieth week of gestation and declined simultaneously until term. A high correlation (r = 0.90, p < 0.00005) was found when the levels of PRL in amniotic fluid and the initial (preincubation) content of PRL in decidua from the same patient were compared. A very high correlation (r = 0.96, p < 0.00005) was seen between the ability of the decidua to produce prolactin in vitro and the corresponding levels of prolactin in amniotic fluid. No significant difference in any parameter tested was noted with respect to either the sex of the fetus or the mode of delivery (p > 0.05). These data are interpreted as indicating (1) that decidual tissue varies throughout late gestation, in both its initial content of prolactin and its ability to synthesize prolactin de novo, in a manner which correlates to a high degree with variations in amniotic fluid prolactin levels and (2) that the decidual tissue is the major source of amniotic fluid prolactin.

Metabolic clearance and production rates of prolactin in man

Metabolic clearance rates (MCR) and production rates (PR) of prolactin (PRL) have been determined by the constant infusion to equilibrium technique in 11 normal subjects, 6 patients with hyperthyroidism, 4 patients with hypothyroidism, and 9 patients with hyperprolactinemia. PRL MCR was also determined tin four patients during dopamine infusion. Mean PRL MCR was 46 +/- 1 ml/min per m2 in women and 44 +/- 3 ml/min per m2 in men, and was significantly correlated with body mass (r = 0.84, P less than 0.001). In contrast with controls, PRL MCR was higher in hyperthyroidism (MCR = 52 +/- 8 ml/min per m2, P less than 0.05), was slightly lower in hypothyroidism (MCR = 38 +/- 10 ml/min per m2, P = NS), and was significantly correlated with serum thyroxine (r = 0.46, P less than 0.02). PRL MCR was lower than controls in hyperprolactinemia (MCR = 40 +/- 5 ml/min per m2, P less than 0.01) and was inversely correlated with serum PRL (r = -0.72, P less than 0.001). PRL MCR was not significantly changed by dopamine infusion. Mean PRL PR for women and men was 211 +/- 74 and 187 +/- 44 micrograms/d per m2, respectively (P = NS). In hyperthyroidism the PRL PR was elevated (PR = 335 +/- 68 micrograms/d per m2, P less than 0.02), but in hypothyroidism the increase (PR = 233 +/- 159 micrograms/d per m2) was not significant. In hyperprolactinemia the PRL PR was extremely high (PR = 31,000 +/- 29,000 micrograms/d per m2). Dopamine infusion decreased RPL PR from 270 to 66 micrograms/d per m2 indicating that its effect was on pituitary PRL secretion and not PRL metabolism. To evaluate possible circulating PRL heterogeneity that might arise during infusion, gel filtration of infusate and serum obtained during the MCR procedure was performed. Labeled monomeric PRL (peak III, Kav (partition coefficient) = 0.4) was partially converted to two larger forms (peaks I and II) in vivo. Peak I (Kav = 0) was 30--40% immunoprecipitable, although peak II (Kav = 0.2) was not immunoprecipitable. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of peak I resulted in greater than or equal to 90% conversion to peak III and restoration of full immunoactivity. Thus, peak I is a noncovalently linked aggregate that is partially immunoactive, and therefore able to alter MCR determinations. These studies demonstrate the impact of hormone heterogeneity on MCR estimations and suggest that gel filtration of immunoprecipitable material be an integral part of future MCR measurements.

Influence of bromocriptine on plasma levels of prolactin and steroid hormones in the 20th week of pregnancy

The influence of bromocriptine, a prolactin antagonist, on maternal plasma and amniotic fluid prolactin (PRL) was investigated in two pregnancies at the 20th week with medical indication for abortion. Voluntary consensus of the patients was obtained. Blood sample determinations demonstrated that bromocriptine inhibits the secretion of PRL both in plasma and amniotic fluid. Since no changes were observed in peripheral maternal steroid concentrations of dehydroepiandrosterone, dehydroepiandrosterone-sulfate, delta 4-androstene-3, 17-dione, testosterone, estradiol, estriol, and cortisol, it is concluded that PRL does not seem to affect maternal and fetal adrenal cortex as supposed in amenorrhoic patients with hyperprolactinemia.

Gel chromatographic properities of human prolactin released from decidua tissue in vitro

Human decidua tissue releases immunoactive prolactin into the medium upon incubation in vitro. The prolactin secreted is indistinguishable from pituitary prolactin in its binding and displacement characteristics, using two different antisera. By gel chromatographic criteria more than 90% of the prolactin is monomeric.

Maternal serum prolactin and its response to TRH in normal and complicated early pregnancy

Maternal serum prolactin levels (PRL) were measured by radioimmunoassay in thirty-four women with either normal or complicated early pregnancy. The basal PRL level (mean +/- S.D.) of 33.4 +/- 16.4 ng/ml in normal pregnancy (n = 15) was similar to the level of 32.7 +/- 18.8 ng/ml in threatened abortion (n = 11) and 32.8 +/- 16.9 ng/ml in hyperemesis gravidarum (n = 8). Two patients, one with blighted ovum and the other with subsequent spontaneous abortion, demonstrated PRL levels lower than the range of 20-63 ng/ml in the control group. The PRL response to 200 microgram of synthetic thyrotropin releasing hormone (TRH) administered intravenously was similar throughout the patient groups. The basal level of PRL in the whole series was more closely related to the level of serum oestradiol (r = 0.778, P less than 0.001) than to that of serum progesterone (r = 0.442, P less than 0.05). However the increments of PRL following TRH administration did not correlate with either oestradiol or progesterone.

Elevated plasma prolactin concentration in cholestasis of pregnancy

The plasma concentrations of prolactin and estradiol-17 beta were measured by specific radioimmunoassays in 150 women with normal pregnancies and 76 women with cholestasis of pregnancy. At 33 to 34 weeks of gestation plasma prolactin concentrations were 187 +/- 23 ng/ml (mean +/- S.E.M.) for normal pregnancy and 341 +/- 38 ng/ml for cholestasis (p less than 0.001). At 35 to 36 weeks they were 254 +/- 24 and 355 +/- 26 ng/ml (p less than 0.01), and at 37 to 38 weeks 175 +/- 14 and 365 +/- 34 ng/ml (p less than 0.001), respectively. Higher prolactin levels in the cholestasis group were not related to differences in plasma estradiol-17 beta concentrations. No correlation was found between plasma prolactin and serum aminotransferase levels, or between prolactin levels and placental weight. The mechanisms by which plasma prolactin levels become elevated in cholestasis of pregnancy remain to be elucidated.

Evidence for a nonpituitary source of amniotic fluid prolactin

Prolactin levels were determined during a gonadotropin-induced pregnancy following hypophysectomy for a chromophobe adenoma. Maternal plasma prolactin concentrations did not vary significantly from prepregnancy values throughout gestation, remaining between 25 and 35 ng/ml. Fetal prolactin levels were 55 ng/ml and maternal levels were 29 ng/ml at delivery. Amniotic fluid prolactin concentration was approximately 100 ng/ml. Decidual tissue isolated from the maternal surface of the chorion released significant amounts of prolactin into the medium during a 24-hour incubation. Final concentrations of prolactin in the incubation medium were as high as 196 ng/ml. It is concluded that after hypophysectomy (1) prolactin is present in the maternal circulation during pregnancy, and the concentration does not change significantly throughout gestation; (2) fetal and amniotic fluid prolactin concentrations near term do not differ significantly from those reported for normal pregnancy; and (3) the capacity of the decidua to release prolactin in vitro is not diminished compared with normal term decidua, suggesting a nonpituitary source of amniotic fluid prolactin.

Hypothesis: placental membranes produce prolactin

Orthodox views for the origin of the high concentration of prolactin (PRL) present in amniotic fluid suggest it is derived from maternal or fetal serum. However, the data on which these conclusions are based can also be interpreted to indicate that this hormone may be a product of placental or periplacental tissues. Trophoblast or amnion do not appear to produce PRL, while PRL synthesis by decidua-chorion is suggested from experiments in the rhesus monkey and by in vitro incubation of human tissue. Production of PRL by an extrapituitary cell is not without precedent and would be a simple explanation for high amniotic fluid PRL concentrations. Moreover, decidual-chorionic PRL would be strategically placed to mediate local functions of this hormone such as osmoregulation and myometrial inhibition.

Cushing's syndrome due to adrenal adenoma with persistent diurnal cortisol secretory rhythm

A 41-yr-old female with presumed Cushing's syndrome was found to have a diurnal cortisol rhythm characterized by low values of 8:00 a.m. and consistently high values at 4:00 p.m. and midnight. Hourly sampling of plasma cortisol over 24 hr confirmed this rhythm, as did measurement of urinary free cortisols in samples collected every 6 hr over 24 hr. Hypercortisolemia was not suppressed by 2 mg of dexamethasone given every 6 hr for 24 hr. The adrenal tissue was responsive to ACTH. Iodocholesterol scanning revealed unilateral activity, and the patient's syndrome was cured by resection of an adrenal adenoma. In this patient a diurnal cortisol secretory pattern was present due to the secretory activity of the adenoma. The cause of the abnormal but persistent diurnal pattern is unknown.

Isolation of prolactin from human amniotic fluid

Amniotic fluid, obtained from women at term, was centrifuged and concentrated by ultrafiltration. The concentrated amniotic fluid was purified by gel filtration on Sephadex G-100 and ion-exchanged chromatography on DEAE-cellulose. The fractions obtained during purification procedures were assayed for prolactin and somatotropin activities by respective radioimmunoassays. The prolactin-rich fraction obtained from ion-exchange chromatography was further purified by isoelectric focusing. A yield of 0.21 mg of highly pruified prolactin containing 40 units/mg was obtained from 1 liter of the amniotic fluid. The prolactin was free of somatotropin and human placental lactogen.

Decidua: a possible source of amniotic fluid prolactin

The source of amniotic fluid prolactin was investigated with the use of amnion, chorion, placenta, and decidual tissue taken from term human pregnancy. Decidua alone of these tissues contained significant quantities of prolactin. The release of decidual prolactin was affected by the presence or absence of oxygen and protein, and the amount of prolactin released far exceeded the decrease in tissue content during incubation. It is concluded that: (1) decidua may be a major source of amniotic fluid prolactin, (2) synthesis of prolactin occurs during incubation of decidua, and (3) sufficient prolactin is present in the decidua to account for that found in amniotic fluid at term.

Prolactin in amniotic fluid: its correlation with maternal plasma prolactin

Prolactin concentrations in amniotic fluid from 319 women with normal pregnancies and 29 women with complicated pregnancies were determined by radioimmunoassay. Prolactin levels varied from 36 ng/ml to 1800 ng/ml mean +/- S.D. = 408 +/- 297) in the normal pregnancy group but showed no definite pattern of rise or fall during pregnancy. No difference in levels was found in complicated pregnancies. Prolactin concentrations in the plasma from 203 of these women were also assayed. The levels in the amniotic fluid were about 9 fold higher than those in the plasma. There was no significant correlation between amniotic fluid and plasma levels of prolactin.