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Effect of the intrauterine contraceptive device upon the biochemical composition of human endometrium
Effect of the intrauterine upon the biochemical
contraceptive
composition
device
of human
endometrium A.
ROSADO,
JUAN
PH.D.,
JOSE
HICKS,
R.
AZNAR,
J.
MARTINEZ-MANAUTOU,
Mexico
City,
M.D. M.D.
M.D. M.D.
Mexico
Biochemical composition of human endometrium was studied during the secretory and proliferative phases of 14 untreated normal young women and of 23 users of a large Lippes Coop placed between 2 and 65 months previously. In the n In-intrauterine contraceptive device (IUD) users, protein and potassium contents of the endometrium were higher and the sodium concentration and the fucosdsialic acid ratio were Cower during the CuteaC than the proliferative phase. The main changes produced by the IUD were a significant decrease of ribonucleic acid (RNA) and sodium, and a 5 times increase in calcium during the proliferative phase and an increase of calcium, sodium, and fucose and in the fucose/sialic acid ratio in the secretroy phase. Secretory phase endometrium of IUD users has amounts of RNA, protein, and potassium lower than those of the control group. The observed changes are discussed in relation to the mechanism of action of the IUD.
T H E G R o w I N G acceptability among the general population of the intrauterine contraceptive device (IUD) as a contraceptive method is pressing on scientific groups to clarify its mechanism of action and the local and systemic effects which it elicits. Definite changes have been reported in the chemical composition of the endometrium in rhesus monkeys bearing an IUD1* and in the
uterine fluid of women usersI Also, studies have been carried out on the aggregates formed around IUD’P after long use by women. The presrnt work was directed toward a study of the biochemical changes in the endometrium of women in which an IUD had been placed. Materials
From the Departamento de Investigacidn Cientifica, Instituto Mexican0 de1 Seguro Social, and the Centro de Investigacidn sobre Fertilidad y Esterilidad. This work was supported in part Grant from the Ford Foundation. for publication
November
Accepted
for publication
April
methods
For this study, a group of 37 patients attending the outpatient Department of the Gynecology and Obstetrics Hospital of the Centro Medico National, Instituto Mexican0 de1 Seguro Social in Mexico City was selected. The patients’ ages ranged from 25 to 35 years, and they had regular menstrual cycles of 28 f 2 days in duration. Twentythree women (Group A) had been wearing a large I,ippes loop placed between 2 and 65 months previously, with a mean for the group of 22 months. A group of 14 untreated nor-
by a
F;;;ived
and
29,
17, 1972.
Reprint requests: Dr. R. Amar, Divisi6n de Biologia de la Reproduction, Departamento de Investigacidn Cientifica, Institute Mexican0 deC Seguro s$ct;l, i partado Postal 73-032, Mextco 9 . .
88
Volume Number
114 1
Endometrial
ma1 women were used as controls (Group B) . During the proliferative phase of the cycle (Days 9 and lo), endometrial biopsies were obtained in 8 women of Group A and 7 in Group B, and during the luteal phase (Days 20 and 2 1) , 15 endometrial biopsies were taken from Group B and 7 in Group A. When 2 biopsies were taken from the same woman, they were always taken during different cycles. The samples, taken with either a Novak or Randall curette, were placed in 5 ml. of 5 per cent perchloric acid* and kept frozen until processing. Recuperation is not a problem because the entire homogenate was always submitted for all determinations. HOWever, we can say that fucose or sialic acid hydrolysis in frozen 5 per cent perchloric acid is negligible during the time the samples were kept, a period always less than one week. The samples were homogenized in a Potter-Elvehjem homogenizer at high speed for 2 minutes. In order to measure Ca++ and was Mg++, 40 ~1 of the total homogenate diluted to 1 ml. with 0.78 per cent ethylenediaminetetra-acetic acid.t Na* and K+ were measured in appropriate dilutions of the same homogenate. All the readings were performed with an atomic absorption spectrophotometer, Unicam Model SP-90 A. Ca++ and Mg++ were measured with the use of absorption at 422.7 and 285 nm., respectively, and Na+ and K+ with the use of emission at 589 and 766 nm., respectively. Fucose was measured in the total homogenate by the Dische and Shettles method.8 To correct for nonspecific color development resulting from the action of H,SO, on the sample, separate aliquots of each sample were heated with the H,SO,, but no cysteine hydrochloride was added after the heating. To correct for the contribution of hexoses, absorbency of the samples was measured at 396 and at 427 nm. Under these conditions, the absorption due to fucose is obtained by subtracting the optical density (O.D.) 396 to O.D. 427 of the sample analyzed without *Analytic reagent Point, Pennsylvania. +Mallinckrodt
grade,
Chemical
Merck
Sharp
Works,
St.
& Dohme, Louis,
Missouri.
West
composition
and
IUD
89
cysteine from the O.D. 396 to O.D. 427 of the sample analyzed with cysteine.” n-Acetylneuraminic acid was measured by the method of WarrenZ4 in the supernatant obtained after boiling the homogenate for 60 minutes and centrifuging the digest at 1,000 x g for 15 minutes. Dry weight was measured by the dichromate method.3 Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and proteins were isolated from 2 ml. of the total homogenate with the method of Munro.” DNA was measured by the method of Burton modified by Giles and Myers,s RNA by the Mejbaum method,21 and protein by the method of Lowry and associates.16 All readings were performed with a spectrophotometer (Unicam Model SP-800 B) . The statistical analysis was made by the twotailed nonpaired t test. Results
In the control group (Table I), no change was found in DNA, RNA, calcium, magnesium, sialic acid, or fucose between the proliferative and luteal phases of the menstrual cycle. Higher concentrations in the protein and potassium content of the endometrium were found during the luteal phase in comparison with those found during the proliferative phase. Sodium concentration was lower during the luteal phase, and the ratio of fucose/ sialic acid in the luteal phase was 40 per cent of that found in the proliferative phase. Table II shows a statistical comparison of the results found during the proliferative phase in the control subjects and the IUD users. No significant changes were observed in the endometrial content of protein, magnesium, sialic acid, and the ratio of fucose/ sialic acid. In the IUD users, RNA and sodium were significantly decreased, and calcium was 5 times higher than in the controls. Potassium and fucose were significantly increased. During the luteal phase (Table III), no significant variation between Groups A and B was observed in sialic acid, but increased values of calcium, sodium, fucose, and the ratio of fucose/sialic acid were found in IUD
90
Rosado
September 1, 1972 Am. J. Obstet. Gynecol.
et al.
Table I. Comparative secretory
phases
biochemical constituents of the human endometrium
in the proliferative and in the control group (B)
Proliferative NO. of cases
Constituent* DNA RN.4
(m)f (P&
7 7 7 7 7
Protein (fig) Calcium (pg) Magnesium ( pg) Sodium ( pg ) Potassium (pg) Sialic acid (pg) Fucose =
*Expressed tExpressed
Not
4.130
acid
Secretory
S.E.
0.490 40.00 0.10 0.034
0.965 0.043 0.097 0.022 0.026
15.20 10.54
0.200 0.012
0.105 0.454 4.996
0.026 0.126 0.884
6 7 6
(pg.)
Fucose/sialic N.S.
:
Mean
phase NO. of cases 7 7 7 7
: 7 5 7 5
phase
Mean
S.E.
P
8.560 0.600 64.80 0.14 0.027
1.889 0.072 0.060
N.S. N.S.
14.18 11.12 0.378 0.412
1.992
0.012 0.011 0.112 0.027 0.123 0.089 0.215
0.001 N.S. N.S. 0.001 0.001 N.S. N.S.
0.010
significant. per
microgram
per milligram
of
DNA.
of dry weight.
users. In these same groups of women, RNA, protein, and potassium were lower than in untreated women. Comment
Studies of the modifications in biochemical composition of the endometrium by the IUD in animals have been numerous and contradictory. Modifications in histamine,lg mucopolysaccharides,5 beta glucuronidase,13 calcium, and acid phosphatase14 have been mentioned. However, no study on the biochemical changes of the human endometrium has been reported up to now. Hilf and colleaguesl’ indicate that the RNA/DNA ratio reflects the functional capacity of the cell. An increase of this ratio indicates a more active cell metabolism. Albaum and Zahal” have reported results in accord with this hypothesis. The increase in the RNA/DNA ratio found in estrogeninduced uterine hypertrophy17 may indicate a more active cel1 metabolism in the tissues of this organ. The significant decrease of RNA found by us in the endometrium of women wearing an IUD in both the proliferative and luteal phases indicates that the metabolic and synthetic activities of the tissue are lower than in control subjects. This decrease in the RNA/DNA ratio may suggest an interference with hormonal action upon the endometrium.
The increased concentration of calcium in the human endometrium of IUD wearers found by us is in accord with the findings in monkeys reported by Kar and co-worker?” and also agrees with the finding of calcium salt deposits on the IUD after prolonged presence in women. 25 It has been suggested that these high calcium levels may be an expression of an inflammatory reaction to a foreign body, but our findings tend to indicate also a hormonal participation since calcium levels were significantly higher in the proliferative than in the secretory phase. Recently, we have shownzO that relatively small concentrations of calcium ions interfere with some important metabolic processes in human spermatozoa, such as oxygen uptake and pyruvate and adenylate kinase activities and with the activity of some hydrolytic enzymes which have been related to capacitation.23 If human spermatozoa require capacitation as the works of Brackett and associates4 and Hicks and colleagues*O suggest, then the significant increase in calcium found in IUD users may modify the microenvironment through which spermatozoa must travel and thereby inhibit the capacitation process. If this is true, our findings will support the hypothesis advanced by Husseis and Ledger.l? Uterine sialic acid concentration tends to increase in the secretory phase of the menstrual cycle in normal women, although the
Volume Number
114 1
Endometrial
Table II. Effect of the IUD
on the biochemical
constituents
composition
and
IUD
91
of the human
endometrium Control
IUD No.
NO.
RNA (pg) Protein (pg) Calcium (fig) Magnesium (89) Sodium (pg) Potassium (pg) Sialic acid (pg) Fucose ( pg) Fucose/sialic acid *Expressed
per
of
of
Constituent*
microgram
cases
Mean
S.E.
cases
Mean
S.E.
P
7 7 7 7 7 7
0.490 40.00 0.10 0.034 15.20 10.54 0.105 0.454 4.996
0.043 0.097 0.022 0.026 0.200 0.012 0.026 0.126 0.884
8
0.338 37.80 0.50 0.039 13.00 11.82 0.242 0.790 5.727
0.036 0.064 0.010 0.019 0.282 0.019 0.073 0.110 1.219
0.025 N.S. 0.001 N.S. 0.001 0.001 N.S. 0.050 N.S.
; 6
; 5 5 5 7 7 8
of DNA.
Table III. Comparative biochemical constituents in the secretory human endometrium of IUD users and the control group
phase of
Control
IUD
No.
of
Constituent*
cases 7
RNA k’5) Protein (ng) Calcium (pg) Magnesium (pg 9) Sodium ( pg) Potassium (pg) Sialic acid (gg) Fucose (fig) Fucose/sialic acid *Expressed
per
No.
microgram
: 7 7 7 : 5
fJf ! Mean 0.600 64.80 0.14 0.0'27 14.18 11.12 0.378 0.412 1.992
REFERENCES Albaum, H. G., 17: 139, 1957.
S.E.
cases
Mean
S.E.
P
0.072 0.060 0.012 0.011 0.112 0.027 0.123 0.089 0.215
11 10 12 11 11 11 7 10 6
0.428 60.60 0.36 0.030 16.13 10.18 0.644 0.750 5.668
0.037 0.048 0.022 0.013 0.147 0.038 0.279 0.152 0.290
0.050 0.010 0.001 N.S. 0.001 0.010 N.S. 0.050 0.010
of DNA.
values do not reach statistical significance due to the large dispersion of the data. However, the fucose/sialic acid ratio shows a significant decrease, reflecting changes in the surface polarity of the endometrium during the secretory phase. In the IUD users, this difference in the fucose/sialic acid ratio is abolished, and we can observe a highly significant increase of this ratio in IUD wearers over that in control subjects (P < 0.01) in the secretory phase. It is known that the fucose and, particularly, the sialic acid concentration of the endometrium are under careful endocrino-
1.
I
and
Zahal,
A.:
Cancer
Res.
1ogic contro1,G and it can be postulated that the special polarity of the membrane may play a role on some mechanism of reproduction such as sperm transport, nidation, etc. RecentIy, Cuatrecasas and Illiano’ have shown that membrane sialic acid participates in the hormone-mediated regulation of tissue metabolism, and Sosaz2 has shown that human spermatozoa have a high content of membrane sialic acid. The relation that all these findings have with the contraceptive action of the IUD through the modification of the fucose/sialic acid ratio is open to speculation.
2.
Ashwell, G.: In Colowick, N. S., editors: Methods
S. P., and Kaplan, in Enzymology. New
92
Rosado
September Am. J. Obstet.
et al.
York, 1957, vol. 3, Academic Press, Inc., p. 81. M.D. Thesis, 1967, Universidad 3. Bernal, A.: National Autonoma de Mexico. 4. Brackett, B. G., Seitz, H. H., Jr., and Mastroianni, L., Jr.: Proc. VII World Congress on Fertility and Sterility, Tokyo/Kyoto, 1971, New York, 1971, Abst. 468. Excerpta Medica Foundation, No. 234. 5. Cooper, B. S., and Hawk, H. W.: Fertil. Steril. 19: 310, 1968. 6. Coppola, J. A., and Ball, J. L.: Steroids 8: 345, 1966. 7. Cuatrecasas, P., and Illiano, G.: J. Biol. Chem. 246:~ 4938, 1971. 8. Dische. Z.. and Shettles. L. B.: T. Biol. Chem. 175: 595, ‘1948. ’ ” 9. Giles, K. W., and Myers, A.: Nature 206: 93, 1965. 10. Hicks, J. J., Pedron, N. N., Martinez-Manautou, J., and Rosado, A.: Fertil. Steril. 23: 172, 1972. 11. Hilf, R., Johnson, J., Brenner, C., and Borman, A.: J. Natl. Cancer Inst. 31: 541, 1963. 12. Husseis, M., and Ledger, W. J.: AM. J. OBSTET. GYNECOL. 108: 221, 1969. 13. Joshi, S. G.: J. Reprod. Fertil. 18: 170, 1969. 14. Kar, A. B., Chandra, H., Kamboj, V. P., Chowdhury, S. R., and Roy, S. K.: AM. J. OBSTET. GYNECOL. 106: 103. 1970.
15.
16.
17. 18.
19. 20.
21.
22. 23.
24. 25.
1, 1972 Gynecol.
Kar, A. B., Engineer, A. D., Gael, R., Kamboj, V. P., Dasgupta, P. R., and Chowdhury, S. R.: AM. J. OBSTET. GYNECOL. 101: 966, 1968. Lowry, O., Rosenbrough, N. J., Farr, A. J., and Randall, R. J.: J. Biol. Chem. 193: 265, 1951. Moore, R. J., and Hamilton, T. H.: Proc. Natl. Acad. Sci. U. S. A. 52: 439, 1964. Munro, H. N.: In Glick, D., editor: Methods of Biochemical Analysis, New York, 1966, vol. 14, Interscience Publishers, Inc., p. 113. Parr, E. L.: J. Reprod. Fertil. 14: 321, 1967. Rosado, A., Hicks, J. J., Martinez-Zedillo, G., Bondani, A., and Martinez-Manautou, J.: Contracention 2: 259. 1970. Schneider, W. C.: Z& Colowick, S. P., and Kaplan, N. S., editors: Methods in Enzymology, New York, 1957, vol. 3, Academic Press, Inc., p. 680. Sosa, A. : Unpublished observations. Srivastava, P. N., Zaneveld, J. D., and Williams, W. L.: Biochem. Biophys. Res. Commun. 39: 575, 1970. Warren, J.: J. Biol. Chem. 234: 1971, 1959. Yang, T., and Yang, W.: AM. J. OBSTET. GYNECOL. 109: 664, 1971.
contraceptive
composition
device
of human
endometrium A.
ROSADO,
JUAN
PH.D.,
JOSE
HICKS,
R.
AZNAR,
J.
MARTINEZ-MANAUTOU,
Mexico
City,
M.D. M.D.
M.D. M.D.
Mexico
Biochemical composition of human endometrium was studied during the secretory and proliferative phases of 14 untreated normal young women and of 23 users of a large Lippes Coop placed between 2 and 65 months previously. In the n In-intrauterine contraceptive device (IUD) users, protein and potassium contents of the endometrium were higher and the sodium concentration and the fucosdsialic acid ratio were Cower during the CuteaC than the proliferative phase. The main changes produced by the IUD were a significant decrease of ribonucleic acid (RNA) and sodium, and a 5 times increase in calcium during the proliferative phase and an increase of calcium, sodium, and fucose and in the fucose/sialic acid ratio in the secretroy phase. Secretory phase endometrium of IUD users has amounts of RNA, protein, and potassium lower than those of the control group. The observed changes are discussed in relation to the mechanism of action of the IUD.
T H E G R o w I N G acceptability among the general population of the intrauterine contraceptive device (IUD) as a contraceptive method is pressing on scientific groups to clarify its mechanism of action and the local and systemic effects which it elicits. Definite changes have been reported in the chemical composition of the endometrium in rhesus monkeys bearing an IUD1* and in the
uterine fluid of women usersI Also, studies have been carried out on the aggregates formed around IUD’P after long use by women. The presrnt work was directed toward a study of the biochemical changes in the endometrium of women in which an IUD had been placed. Materials
From the Departamento de Investigacidn Cientifica, Instituto Mexican0 de1 Seguro Social, and the Centro de Investigacidn sobre Fertilidad y Esterilidad. This work was supported in part Grant from the Ford Foundation. for publication
November
Accepted
for publication
April
methods
For this study, a group of 37 patients attending the outpatient Department of the Gynecology and Obstetrics Hospital of the Centro Medico National, Instituto Mexican0 de1 Seguro Social in Mexico City was selected. The patients’ ages ranged from 25 to 35 years, and they had regular menstrual cycles of 28 f 2 days in duration. Twentythree women (Group A) had been wearing a large I,ippes loop placed between 2 and 65 months previously, with a mean for the group of 22 months. A group of 14 untreated nor-
by a
F;;;ived
and
29,
17, 1972.
Reprint requests: Dr. R. Amar, Divisi6n de Biologia de la Reproduction, Departamento de Investigacidn Cientifica, Institute Mexican0 deC Seguro s$ct;l, i partado Postal 73-032, Mextco 9 . .
88
Volume Number
114 1
Endometrial
ma1 women were used as controls (Group B) . During the proliferative phase of the cycle (Days 9 and lo), endometrial biopsies were obtained in 8 women of Group A and 7 in Group B, and during the luteal phase (Days 20 and 2 1) , 15 endometrial biopsies were taken from Group B and 7 in Group A. When 2 biopsies were taken from the same woman, they were always taken during different cycles. The samples, taken with either a Novak or Randall curette, were placed in 5 ml. of 5 per cent perchloric acid* and kept frozen until processing. Recuperation is not a problem because the entire homogenate was always submitted for all determinations. HOWever, we can say that fucose or sialic acid hydrolysis in frozen 5 per cent perchloric acid is negligible during the time the samples were kept, a period always less than one week. The samples were homogenized in a Potter-Elvehjem homogenizer at high speed for 2 minutes. In order to measure Ca++ and was Mg++, 40 ~1 of the total homogenate diluted to 1 ml. with 0.78 per cent ethylenediaminetetra-acetic acid.t Na* and K+ were measured in appropriate dilutions of the same homogenate. All the readings were performed with an atomic absorption spectrophotometer, Unicam Model SP-90 A. Ca++ and Mg++ were measured with the use of absorption at 422.7 and 285 nm., respectively, and Na+ and K+ with the use of emission at 589 and 766 nm., respectively. Fucose was measured in the total homogenate by the Dische and Shettles method.8 To correct for nonspecific color development resulting from the action of H,SO, on the sample, separate aliquots of each sample were heated with the H,SO,, but no cysteine hydrochloride was added after the heating. To correct for the contribution of hexoses, absorbency of the samples was measured at 396 and at 427 nm. Under these conditions, the absorption due to fucose is obtained by subtracting the optical density (O.D.) 396 to O.D. 427 of the sample analyzed without *Analytic reagent Point, Pennsylvania. +Mallinckrodt
grade,
Chemical
Merck
Sharp
Works,
St.
& Dohme, Louis,
Missouri.
West
composition
and
IUD
89
cysteine from the O.D. 396 to O.D. 427 of the sample analyzed with cysteine.” n-Acetylneuraminic acid was measured by the method of WarrenZ4 in the supernatant obtained after boiling the homogenate for 60 minutes and centrifuging the digest at 1,000 x g for 15 minutes. Dry weight was measured by the dichromate method.3 Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and proteins were isolated from 2 ml. of the total homogenate with the method of Munro.” DNA was measured by the method of Burton modified by Giles and Myers,s RNA by the Mejbaum method,21 and protein by the method of Lowry and associates.16 All readings were performed with a spectrophotometer (Unicam Model SP-800 B) . The statistical analysis was made by the twotailed nonpaired t test. Results
In the control group (Table I), no change was found in DNA, RNA, calcium, magnesium, sialic acid, or fucose between the proliferative and luteal phases of the menstrual cycle. Higher concentrations in the protein and potassium content of the endometrium were found during the luteal phase in comparison with those found during the proliferative phase. Sodium concentration was lower during the luteal phase, and the ratio of fucose/ sialic acid in the luteal phase was 40 per cent of that found in the proliferative phase. Table II shows a statistical comparison of the results found during the proliferative phase in the control subjects and the IUD users. No significant changes were observed in the endometrial content of protein, magnesium, sialic acid, and the ratio of fucose/ sialic acid. In the IUD users, RNA and sodium were significantly decreased, and calcium was 5 times higher than in the controls. Potassium and fucose were significantly increased. During the luteal phase (Table III), no significant variation between Groups A and B was observed in sialic acid, but increased values of calcium, sodium, fucose, and the ratio of fucose/sialic acid were found in IUD
90
Rosado
September 1, 1972 Am. J. Obstet. Gynecol.
et al.
Table I. Comparative secretory
phases
biochemical constituents of the human endometrium
in the proliferative and in the control group (B)
Proliferative NO. of cases
Constituent* DNA RN.4
(m)f (P&
7 7 7 7 7
Protein (fig) Calcium (pg) Magnesium ( pg) Sodium ( pg ) Potassium (pg) Sialic acid (pg) Fucose =
*Expressed tExpressed
Not
4.130
acid
Secretory
S.E.
0.490 40.00 0.10 0.034
0.965 0.043 0.097 0.022 0.026
15.20 10.54
0.200 0.012
0.105 0.454 4.996
0.026 0.126 0.884
6 7 6
(pg.)
Fucose/sialic N.S.
:
Mean
phase NO. of cases 7 7 7 7
: 7 5 7 5
phase
Mean
S.E.
P
8.560 0.600 64.80 0.14 0.027
1.889 0.072 0.060
N.S. N.S.
14.18 11.12 0.378 0.412
1.992
0.012 0.011 0.112 0.027 0.123 0.089 0.215
0.001 N.S. N.S. 0.001 0.001 N.S. N.S.
0.010
significant. per
microgram
per milligram
of
DNA.
of dry weight.
users. In these same groups of women, RNA, protein, and potassium were lower than in untreated women. Comment
Studies of the modifications in biochemical composition of the endometrium by the IUD in animals have been numerous and contradictory. Modifications in histamine,lg mucopolysaccharides,5 beta glucuronidase,13 calcium, and acid phosphatase14 have been mentioned. However, no study on the biochemical changes of the human endometrium has been reported up to now. Hilf and colleaguesl’ indicate that the RNA/DNA ratio reflects the functional capacity of the cell. An increase of this ratio indicates a more active cell metabolism. Albaum and Zahal” have reported results in accord with this hypothesis. The increase in the RNA/DNA ratio found in estrogeninduced uterine hypertrophy17 may indicate a more active cel1 metabolism in the tissues of this organ. The significant decrease of RNA found by us in the endometrium of women wearing an IUD in both the proliferative and luteal phases indicates that the metabolic and synthetic activities of the tissue are lower than in control subjects. This decrease in the RNA/DNA ratio may suggest an interference with hormonal action upon the endometrium.
The increased concentration of calcium in the human endometrium of IUD wearers found by us is in accord with the findings in monkeys reported by Kar and co-worker?” and also agrees with the finding of calcium salt deposits on the IUD after prolonged presence in women. 25 It has been suggested that these high calcium levels may be an expression of an inflammatory reaction to a foreign body, but our findings tend to indicate also a hormonal participation since calcium levels were significantly higher in the proliferative than in the secretory phase. Recently, we have shownzO that relatively small concentrations of calcium ions interfere with some important metabolic processes in human spermatozoa, such as oxygen uptake and pyruvate and adenylate kinase activities and with the activity of some hydrolytic enzymes which have been related to capacitation.23 If human spermatozoa require capacitation as the works of Brackett and associates4 and Hicks and colleagues*O suggest, then the significant increase in calcium found in IUD users may modify the microenvironment through which spermatozoa must travel and thereby inhibit the capacitation process. If this is true, our findings will support the hypothesis advanced by Husseis and Ledger.l? Uterine sialic acid concentration tends to increase in the secretory phase of the menstrual cycle in normal women, although the
Volume Number
114 1
Endometrial
Table II. Effect of the IUD
on the biochemical
constituents
composition
and
IUD
91
of the human
endometrium Control
IUD No.
NO.
RNA (pg) Protein (pg) Calcium (fig) Magnesium (89) Sodium (pg) Potassium (pg) Sialic acid (pg) Fucose ( pg) Fucose/sialic acid *Expressed
per
of
of
Constituent*
microgram
cases
Mean
S.E.
cases
Mean
S.E.
P
7 7 7 7 7 7
0.490 40.00 0.10 0.034 15.20 10.54 0.105 0.454 4.996
0.043 0.097 0.022 0.026 0.200 0.012 0.026 0.126 0.884
8
0.338 37.80 0.50 0.039 13.00 11.82 0.242 0.790 5.727
0.036 0.064 0.010 0.019 0.282 0.019 0.073 0.110 1.219
0.025 N.S. 0.001 N.S. 0.001 0.001 N.S. 0.050 N.S.
; 6
; 5 5 5 7 7 8
of DNA.
Table III. Comparative biochemical constituents in the secretory human endometrium of IUD users and the control group
phase of
Control
IUD
No.
of
Constituent*
cases 7
RNA k’5) Protein (ng) Calcium (pg) Magnesium (pg 9) Sodium ( pg) Potassium (pg) Sialic acid (gg) Fucose (fig) Fucose/sialic acid *Expressed
per
No.
microgram
: 7 7 7 : 5
fJf ! Mean 0.600 64.80 0.14 0.0'27 14.18 11.12 0.378 0.412 1.992
REFERENCES Albaum, H. G., 17: 139, 1957.
S.E.
cases
Mean
S.E.
P
0.072 0.060 0.012 0.011 0.112 0.027 0.123 0.089 0.215
11 10 12 11 11 11 7 10 6
0.428 60.60 0.36 0.030 16.13 10.18 0.644 0.750 5.668
0.037 0.048 0.022 0.013 0.147 0.038 0.279 0.152 0.290
0.050 0.010 0.001 N.S. 0.001 0.010 N.S. 0.050 0.010
of DNA.
values do not reach statistical significance due to the large dispersion of the data. However, the fucose/sialic acid ratio shows a significant decrease, reflecting changes in the surface polarity of the endometrium during the secretory phase. In the IUD users, this difference in the fucose/sialic acid ratio is abolished, and we can observe a highly significant increase of this ratio in IUD wearers over that in control subjects (P < 0.01) in the secretory phase. It is known that the fucose and, particularly, the sialic acid concentration of the endometrium are under careful endocrino-
1.
I
and
Zahal,
A.:
Cancer
Res.
1ogic contro1,G and it can be postulated that the special polarity of the membrane may play a role on some mechanism of reproduction such as sperm transport, nidation, etc. RecentIy, Cuatrecasas and Illiano’ have shown that membrane sialic acid participates in the hormone-mediated regulation of tissue metabolism, and Sosaz2 has shown that human spermatozoa have a high content of membrane sialic acid. The relation that all these findings have with the contraceptive action of the IUD through the modification of the fucose/sialic acid ratio is open to speculation.
2.
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