Plasma human chorionic somatomammotropin deficiency in a normal pregnancy is the consequence of low concentration of messenger RNA coding for human chorionic somatomammotropin

Plasma human chorionic somatomammotropin deficiency in a normal pregnancy is the consequence of low concentration of messenger RNA coding for human chorionic somatomammotropin C. Hubert,

D. Descombey,

F. Mondon,

and

F. Daffos

Park, Fruncr Human chorionic somatomammotropin pregnancies. Presented is the case hCS was detected. The concentration

evaluated to determine the level on

(hCS) is important in the hormonal monitoring of human of a clinically normal pregnancy in which a very low plasma level of of messenger ribonucleic acid (mRNA) coding for hCS was which the deficiency occurred. (AM. J. OBSTET. GYNEC~X. 147:676,

1983.)

‘1‘0 evaluate the fetal well-being and to monitor the placental function, human chorionic somatomammotropin (hCS) has been used as a screening test.‘. ’ Plasma levels of hCS increase linearly as the pregnant) progl-esses. Verv few cases have been reported to have partial”+” 01. complete’. ’ deficiency of hCS associated or not with a defined pathologic condition. The hCS content in the plasma or in the placenta was estimated by radioimmunoassay, with only the immunologic properties of the hormone considered. No study on hCS synthesis or on the messenger RNA (mRNA) coding for hCS has been undertaken. A clinically normal pregnancy with a very low plasma level of hCS was detected. The ;:oncentration of mRNA coding for hCS was determined to establish the level on which the deficiency occuned. Case report The patient was a 25year-old primigravid lvoman. Her pregnancy had progressed normally, with a uterine si/r and a fetal biparietal diameter compatible with gestational age. At 3.4 weeks’ gestation, a routine sampling of blood showed the hCS level to be very low (I.09 pgiml). and it remained below 1.2 pg/ml un;il the end of’ pregnancy,. Prolactin, growth hormone, and estrio1 levels were found to be within the normal range for gestation. At the thirty-seventh week, the patient was spontaneously delivered of a healthy 3,300 gm boy From the Labor&o& de Chimir Harmon& Mater&i de Port-Royal, rind the Sewice Cvnkologiyue Obstbtriyw, HSpital Notre-Dame de Bon Src0ur.Y. Supported by the Crntre National de la Recherche Scie+ique (E.R. 123) and the Institut National de la Santb et de la Recherchr Wdicale ( U. 166). Rrceisvd-for publication March 22, 1983. Accepted July 11, 1983. Reprint wyuests: DT. C. Hubert, Laboratoire de Chimie Hononalr .Wutrrnit~. 123, Boulezjard de Port-Royal, 75014 Park, France.

676

with Apgar scores of 10 at 1 minute and 10 at 5 minutes. The placenta, which weighed 600 gm, showed neither macroscopic nor microscopic abnormalities. The patient chose not to breast-feed, and lactation was suppressed. Material Hormone

and methods concentrations

in

maternal

blood

and

Sequential sampling of maternal venous blood was performed throughout pregnancy. The hCS was measured directly from plasma by two distinct radioimmunoassay kits (C.I.S. Gifsur-Yvette, France; Lepetit, Milan, Italy). Respective radioimmunoassays for plasma growth hormone, prolactin, a-fetoprotein, and nonconjugated estriol were carried out. Twenty-fourhour urinary excretion of total estriol was evaluated on many occasions. In addition, fasting and postprandial plasma glucose was determined. Preparation of placental RNA. The placenta was weighed just after delivery, immediately frozen in liquid nitrogen, and stored at -80” C. To prepare total RNA. 10 gm of tissue was homogenized and processed as previously described.!’ Estimation of hCS mRNA concentration by hybridization. A specific :‘H-hCS complementary DNA (cDNA) probe was prepared by a reverse transcription of hCS mRNA, as previously reported.” The concentration of hCS mRNA in the total placental RNA fractions was estimated by hybridization with the synthesized cDNA. After incubation at 65” C for 24 hours, the extent of hybridization was determined by the resistance of the cDNA to S, nuclease. For each placental RNA preparation, the corresponding Ro . t (RNA concentration X time of incubation) was determined at 50% of maximal hybridization of the cDNA with the RNA tested. For a constant time of hybridization, the urine.

Plasma

Volume Number

147 6

Table

I. Hormone

concentrations

in maternal

serum and urine

during

hCS deficiency

in normal

pregnatwy

677

the last 4 weeks of pregnancy V?ilWZry

Weeks of

Pregnav

&El)

34 35

Pro/a&z (nglml)

Growth hormone (nglml)

1.09

120

6.1

1.04

99

9.0

a-Feto-

protein Wml) 204 204

Plasma estriol

h&d) 4.04

6WiOl

(mgl.24 hrlgm creatinine)

Glucose (pm

14.7

Fasting 0.82

Postprandial 1.33 36 37

1.00

Normal range (34 to 37 wk, 10th to 90th percentile)

1.20

116 112

7.9 7.3

4.30-15.00

94-360


concentration of RNA sequences coding for hCS can be thus expressed as 1 Ro.t% in M-’ . set-‘. RNA determination. RNA after purification was quantitated by spectrophotometric analysis. One milligram of purified RNA has an absorption of 20 at 260 nm. Results The levels of plasma hCS were determined repeatedly from the thirty-fourth week until delivery, as shown in Table I. The values were steadily under the lower limit of normal range. These results were considered to be in the abnormally low zone in both radioimmunoassay systems. Unfortunately. there was no determination of other specific proteins from the placenta. Plasma a-fetoprotein concentration was in the normal range. In the same interval of pregnancy, serum growth hormone and prolactin were also normal. The urinary estriol production showed normal levels. Both fasting and postprandial glucose were normal. Table I clearly shows normal concentrations, in the range of the tenth to ninetieth percentile, for all parameters, with the exception of hCS. To test messenger activity of RNA in a translating cell-free system, fresh placenta must be processed immediately. The thawing of frozen material released large amount of RNases, destroying the biologic activity of mRNA, determined in vitro. First, we verified that the integrity of mRNA was still available to permit enough hybrid extent with a cDNA probe and to quantify the mRNA concentration coding for hCS. The specificity of the reaction was assessed as previously described.g The concentration of 1.19 M-’ x set-’ for hCS mRNA in a RNA preparation obtained from a frozen term placenta was comparable to the concentrations obtained from fresh tissues (1.24 M-’ X set-‘).‘”

5.92 7.12

loo-360

2.4-15

20.8 23.0 >6.0

Gl

The concentration of mRNA coding for hCS in the placenta of the patient was 0.29 M-’ x set-‘, corresponding to four times less specific mRNA per RNA unit. The difference found in the concentration of hCS mRNA was not found in the quantity of total RNA per milligram of tissue, which remained similar to normal term placentas. Comment We are uncertain of the physiologic properties of hCS, but its importance in the hormonal monitoring of human pregnancies is well established. However, in extremely rare pregnancies which otherwise seemed to be normal, there was a deficiency of plasma hCS.“-* The incidence of this defect was one in 12,000 or 20,000 pregnancies. The structure and biologic properties of hCS, hGH, and prolactin show great similarities, and correlations between the hormone concentrations have been postulated. In the present case, a compensatory role of growth hormone and prolactin was suggested, but both growth hormone and prolactin levels during the third trimester of pregnancy were steadily in the normal range, so that no such adjustment was indicated. However, it is possible that other substances compensated for the low levels of plasma hCS or that hormone concentration was high enough to achieve an uneventful pregnancy. Furthermore, hCS is considered to have a role in maternal metabolism, and many studies have attempted to correlate hCS levels and plasma glucose levels. Consequently, in this case of hCS deficiency, blood glucose levels were investigated, but no abnormality was detected. In spite of a very low level of hCS, the outcome of pregnancy can be uneventful, without any other noticeable changes in substances which are thought to be involved in hCS regulation. Histologically, each of the six placentas associated with reported hCS deficiency appeared to be normal,

Hubert

et al

November

15, 1983

Am. J. Obstet. Gynecd

thereby suggesting rather a defect at the molecular level. Principally, the immunologic properties of hCS were concerned, and, recently, a pregnancy associated with a complete, rather than partial, deficiency of hCS was characterized by a deletion of the hCS gene.x In these cases, no studies were carried out on hCS synthesis or on the concentration of the messenger RNA coding for the hormone. In this report, we demonstrated that the partial deficit of plasma hCS was due to a low concentration of the specific mRNA, on the assumption that protein synthesis remained normal. At present, the patient is in the thirtieth week of pregnancy and has a normal plasma hCS concentration. This fact contributes to Wurzel’s report that suggests a heterozygosity for the abnormal hCS gene cluster in the parents.

REFERENCES 1. Spellacy. McCreary,

W. N., Teoh, S. S., Buhi, W. C., Birk. S. A., and S. A.: Value of hCS in managing high-risk pregnancies, AM. J. OBSTET. GYNECOL. 109:588, 197 1. 2. Daffos, F., Freund. M., Sarrot, G., Zimmer, R., Feinstein, M. C.. and Chartier. M.: In&& des dosages de hCS au

tours des grossesses compliquCes de maladie vasculor&ale, Pathol. Biol. (Paris) 29:384, 1981. D., and Pepersen, H.: Extremely low 3. Gaede, P., Trolle, hPL values in an otherwise uneventful pregnancy preceding delivery of a normal baby, Acta Obstet. Gynecol. Stand. 57:203, 1978. J., Bernet& A., McCarrick, J., and Allerhand, 4. Moshirpur, J.: hPL deficiency with normal estriol levels in a normal pregnancy, Obstet. Gynecol. 57:6, 1981. I. B., and Carlton, M. A.: Isolated defect in hPL 5. Borody, synthesis in a normal pregnancy, Br. J. Obstet. Gynaecol. 88:447, 1981. 6. Anthony, A. F., and Letchworth, A. T.: Placental protein profile and glucose studies in a normal pregnancy with extremely low levels of hPI+ Br. J. Obstet. Gynaecol. 89:241, 1982. 7. Nielsen, P. V., Pedersen, H., and Kampmann, E. M.: Absence of hPL in an otherwise uneventful pregnancy, AM. J. OBSTET. GYNECOL. 135:322, 1979. 8. Wurzel, J. M., Parks, J. S., Herd, J. E., and Nielsen, P. V.: A gene deletion is responsible for absence of hCS, DNA 1:251, 1982. 9. Hubert, C., Mondon, F., and Cedard, L.: Distribution quantification and biological activity of messenger RNA coding for hCS during normal pregnancy, Mol. Ceil. Endocrinol. 24:339, 1981. 10. Hubert, C., Mondon, F., and Cedard, L.: Biologic activity and quantification of messenger RNA coding for hCS in normal and intrauterine growth-retarded pregnancies, AM. J. OBSTET. GYNECOL. 144~722, 1982.

Spurt release of oxytocin during surgical induction of labor in women T. Chard London,

and G. L. D. Gihbens England

Oxytocin levels were measured in closely spaced samples of maternal blood from 10 women who underwent amniotomy for induction of labor. The procedure was associated with a spurt release of oxytocin, the highest frequency being found during sweeping and rupture of the membranes. It was concluded that the main stimulus to this release was vaginal distention (Ferguson’s reflex) and that the same mechanism probably accounts for the increase in maternal oxytocin during the expulsive phase of labor. (AM. J. OBSTET. GYNECOL. 147:678, 1983.)

Distention of the vagina can induce uterine contractions in a variety of species. This is thought to be mediated by a spinal reflex (Ferguson’s reflex),’ of which oxytocin

forms

the

afferent

arm.

Direct

evidence

for

this, by measurement of circulating oxytocin, has been presented in the cow,’ the ewe,“. 4 and the goat.‘, fi From the Departments of Reproductive Physiology and Obstetrics and Gynaecology, St.Bartholomew’s Hospital Medical College and The London Hospital Medical College. Received for publication November 8, 1982. Revised May 2, 1983. Accepted July I 1, 1983. Rqtnint requests: Dr. T. Chard, Department of Reproductive Physiology, St. Bartholomew’s Hospital, 51-53 Bartholomew Close, West Smitfzfield, London EClA 7BE, England.

67%

However, information in women is limited, and the only significant study’ claimed no increase in oxytocin associated with amniotomy for the induction of labor-a process which would be expected to provide a very strong stimulus for the reflex. We now report that the frequency of spurt release of oxytocin is substantially increased during the procedure of amniotomy in the human.

Subjects and methods Ten patients (aged 18 to 23 years) gave informed consent to the procedure. All were 5 to 10 days beyond term by certain dates and were undergoing routine induction of labor for this indication. All had uncompli-