275
PLASMA ESTROGENS, PROGESTERONE AND CHORIONIC GONADOTROPIN IN PREGNANT RHESUS MONKEYS (Macaca mulatta) AFTER OVARIECTOMY Gary D. Hodgen and William W. Tullner Section on Endocrinology, Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md. 20014 Received:
12/3/74 ABSTRACT
Maternal peripheral plasma concentrations of estrone (El) , estradiol-17~ (E2) , and progesterone (P) were determined in 4 rhesus monkeys ovariectomized in early pregnancy (22-24 days). After ovariectomy, plasma concentrations of E I and E 2 were basal for i to 2 weeks. In contrast, slightly higher estrogen levels, which may be attributed to the ovaries, were found in intact pregnant monkeys. E 2 levels increased rapidly after this and exceeded those of E~ until the 5th month of gestation. From that time until parturition, E1 levels equaled or exceeded those of E2 in most instances. The pattern of P concentrations was similar to that observed in intact monkeys. Urinary chorionic gonadotropin (MCG) levels in ovariectomized monkeys were not significantly different from those found in normal pregnancies. Thus, the patterns for circulating El, E2 and P, as well as for the excretion of MCG, after ovariectomy were remarkably similar to those found in intact, pregnant rhesus monkeys, indicating minimal ovarian influence. INTRODUCTION The demonstration that ovariectomy of rhesus monkeys as early as the twenty-first day of gestation did not interfere with the normal course of gestation,
delivery of young, or lactation
(i), raised ques-
tions regarding the hormonal status of these primates.
More recently,
the finding that the corpus luteum of pregnancy undergoes rejuvenation shortly before parturition
in this species
lems with regard to understanding gestation.
(2) presented further prob-
the role of the ovaries throughout
The present report describes alterations in plasma levels
of estradiol-17~
(E2), estrone
(El) , and progesterone
excretion patterns of macaque chorionic gonadotropin of monkeys ovariectomized
Volume 25, Number 2
(P) and urinary (MCG) in a group
at 22-24 days of pregnancy.
~
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R
o
x ~
s
February,
1975
276
8
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MATERIALS AND METHODS Five pregnant adult monkeys were bilaterally ovariectomized at 2224 days gestation using surgical procedures described previously (i). Details of mating and determination of pregnancy have been reported (3). Heparlnized blood samples ( 5 ml) were collected at intervals throughout pregnancy. Plasma was frozen at -10C until assayed. Radioimmunoassay methods for determination of plasma progesterone, estradiol-178, and estrone were described in (4). Twenty-four hr urine specimens were collected, extracted (3), and quantified for MCG activity in a biological assay as previously reported (5). Urine samples were obtained from 5 monkeys ovariectomlzed early in pregnancy. However, one female aborted on the 143rd day and data on plasma steroids from this animal were not included in this report. RESULTS Concentrations of P, El, and E~ were determined throughout pregnancy in the peripheral plasma of four rhesus monkeys which were ovariectomized in early gestation.
Except for a single value (monkey C143) at
the time of conception, El concentrations equaled or exceeded those of E2 during the first 3 weeks of gestation.
After ovariectomy, El and E2
abruptly declined to basal levels for a period of one to two weeks.
El
and E2 levels began rising between 35 to 40 days after conception but E2 concentrations exceeded those of El until the fourth or fifth month (Fig i and 3a).
At that time, El levels rose rapidly until they equaled
or exceeded those of E2 in the pre-partum period.
Levels of both estro-
gens declined markedly soon after parturition. Plasma P patterns in ovariectomized monkeys (Fig 2 and 3b) were similar to those previously reported for intact pregnant rhesus monkeys (3,6,7), although P levels in one animal (monkey 248) were markedly elevated for several days after ovariectomy.
Parturition was followed
by a rapid decline in P levels (Fig 2). Chorionic gonadotropin excretion in 24 hour urine samples from 7 normal and 5 ovariectomized monkeys are shown in Fig 4.
No significant
S
1000
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1~.0
= : Est rodiol- 17/~ 0----0 Estrone
I
I)
ll
277
~ 686-V
Deli-i-, ~
800
o.
Ovorieclomy 2O0
~0 M
800[-
l
20 - -
40
60
80 I00 GESTATION (DAYS)
: Estrcld,ol- ;7~ o--- -o Eslrone
120
)40
160
)80
? 704-W
600 L
ery
p --d/
#0 M
800
¢
20
40
¢ £sTrodlOl"17~
c.---oE.,o.e
60
80 I00 GESTATpON(DAYS)
120
o
140
160
180
?CJ43
~
Da,~.,y
6OO
400
2OO ~p
~0 M
20
40
60
80 I00 GESTATION(DAYS)
120
140
160
180
Fig. i. Maternal peripheral plasma levels of estradiol and estrone in a series of rhesus monkeys before and after ovariectomy in early gestation
278
~
'~- 1=, : R o
i
-n~
Ovoriectomy
~og6v
w4
~2 Q I
I
~0 M
I
20
40
I
60
I
80 I00 GESTATION (DAYS)
Ovariect0my
I
I
I
120
140
I
160
180
? 704 W
i 6
~0 M
20
40
60
80 JO0 GESTATION (DAYS)
120
140
r60
180
9 cf43
----'6
~2 I
/
I
I
0
2'0
40
60
I
l
1
80 I00 GESTATION(DAYS)
I
120
I
L
140
~60
•
I
J80
Fig. 2. Maternal peripheral plasma levels of progesterone in a series of rhesus monkeys before and after ovariectomy in early gestation.
8
I " ]El ] B , O
I
I)
ll
279
ISG7 1400 I
(~248
12OO~-
ISIAl
Oebvery
~. ~ Esfr0d~01"17~ O- ---0 Eslrone
/
I I
,ooo F
~1 I
oooF
of
........
400
//
R
~'o
M
so
,~
GESTATION(DAYS)
/
,2o,;,:o,so,~,,o
' "O IB
Fig. 3a. Plasma levels of estradiol and estrone before and after ovariectomy in early gestation.
23;2
~248
I0 Parturit~n
8
l
/
~6
4
(X~rec~om I
2O
40
60
I
I
I
80 I00 120 GESTATION (DAYS)
I
I
I
140
160
180
Fig. 3b. Plasma levels of progesterone before and after ovariectomy in early gestation.
S
280
~
~" ~R, O I
~'j~
differences in hormone output were found after ovariectomy throughout the limited period of chorionic gonadotropin excretion.
300
•
[] --
Intocl Monkeys Ovo.ectomlzed Monkeys
25O
~200 ~ ~50 Q_
ioo N 50 16
17
18
19 20 21
22
23
24
25 26
27
28
29
30
31
32
DAY OF PREGNANCY
Fig. 4. Daily urinary MCG excretion ~HCG equivalents) in a series of 7 intact and 5 ovariectomized rhesus monkeys. Ovariectomy between 22nd to 24th day of pregnancy.
DISCUSSION In normal pregnant animals in this colony, both E2 and El decline tc levels approximating 50 pg/ml plasma at about 30-35 days after conceptiol This diminution is followed by a rise in E2, with Ez remaining at low cot centrations for the ensuing 2 months (3,4,7).
The low levels of Ez and
E2 found in intact animals, as compared with the almost complete absence of measurable estrogens shortly after ovariectomy, indicate that the ovaries are the principal source of these estrogens up to about 5 to 6 weeks of pregnancy.
Except for the decrease in plasma E I and E2 soon
after ovariectomy, the pattern of estrogen production is similar to that of intact pregnant animals at comparable stages of gestation.
Data fro=
the present study, as well as previous reports (3,4,8), suggest that th~
~
TXZ~.OX]t~m
281
feto-placental complex assumes the major role in estrogen production at about 6 weeks gestation.
After the 5th or 6th week, a rise in plasma E2
concentration occurs and continues until term.
El, on the other hand,
undergoes a slow but continuous rise which is accelerated during the 4th or 5th month.
Results presented here demonstrate
in estrogen level are independent of the ovaries.
that these increases In a related study of
fetectomized monkeys, we have shown that the fetus is the major source of E I and E2 or their precursors during the last 3 months for E2 and, the final month prior to parturition for El (4). Although one monkey exhibited a sharp rise in plasma P levels shortly after ovariectomy,
the usual pattern for P production remained similar
to that previously reported for intact animals
(3,6,7).
It should be
noted that there is a peak in plasma P levels in most intact monkeys during the 4th or 5th week of gestation study were ovariectomized
(3,6,7) and that the monkeys in this
about one week before that time.
Despite ova-
riectomy early in the 4th week, rising P levels were observed in all four monkeys during the week in~nediately
following surgery.
This confirms an
earlier report suggesting a predominantly placental origin for P at this stage of pregnancy
(6).
The rise in E2 levels which occurs several days
after this progesterone peak can be conclusively dissociated from the ovaries on the basis of the present experiments and shown
to be of fetal
origin (4). The transient rise and fall in plasma P in the presence or absence of the ovaries during weeks 4 and 5 could possibly arise from stimulation of placental P synthesis by MCG, since MCG levels are at maximum several days before the rise in P is observed.
We have presented data
282
~
T ~'
~ o
x mmm
showing that ovariectomy had no measurable influence on the rate of excretion of MCG. The rapid decline in P levels after parturition confirms the earlier studies which emphasized the dominant role of the placenta in P production after the third week in pregnancy.
It appears that failure
to maintain pregnancy after ovariectomy earlier than the 3rd week in gestation, unless exogenous progesterone is administered, is related to the inability of the placenta to provide an adequate quantity of P (9). In conclusion, present findings show that, except for a decrease in estrogen levels shortly after ovariectomy, the general pattern observed for El, E2 and P concentrations in maternal plasma throughout gestation cannot be differentiated from those found in intact pregnant rhesus monkeys and confirm the dispensability of the ovaries for maintenance of pregnancy in this species. ACKNOWLEDGMENTS We gratefully acknowledge the expert technical assistance of Don Barber, Charles Turner, and Louise Metz. REFERENCES i. 2. 3. 4. 5. 6. 7. 8. 9.
Tullner, W. W. and Hertz, R., ENDOCRINOLOGY 78, 1076 (1966). Treloar, O. L., Wolfe, R. C. and Meyer, R. K., ENDOCRINOLOGY 91, 665 (1972). Hodgen, G. D., Dufau, M. L., Catt, K. J. and Tullner, W. W., ENDOCRINOLOGY 91, 896 (1972). Tullner, W. W. and Hodgen, G. D., STEROIDS 24 (in press). Nixon, W. E., Hodgen, G. D., Niemann, W. H., Ross, G. T. and Tullner, W. W., ENDOCRINOLOGY 90, 1105 (1972). Neill, J. D., Johansson, E. D. B. and Knobil, E., ENDOCRINOLOGY 84, 45 (1969). Hodgen, G. D. and Tullner, W. W. Abstract 56th ANNUAL MEETING of the ENDOCRINE SOC. p. A-248 (1974). Bosu, W. T. K., Johansson, E. D. B., and Gemzell, C. ACTA ENDOCR. (Kbh.) 75, 601 (1974). Meyer, R. K., Wolf, R. C. and Arslan M., PROC. 2nd INT. CONGR. PRIMAT. ATLANTA, GA. 1968, ed. H. O. Hofer, Vol 2, Karger, Basel/New York, 1969, p. 30.
PLASMA ESTROGENS, PROGESTERONE AND CHORIONIC GONADOTROPIN IN PREGNANT RHESUS MONKEYS (Macaca mulatta) AFTER OVARIECTOMY Gary D. Hodgen and William W. Tullner Section on Endocrinology, Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md. 20014 Received:
12/3/74 ABSTRACT
Maternal peripheral plasma concentrations of estrone (El) , estradiol-17~ (E2) , and progesterone (P) were determined in 4 rhesus monkeys ovariectomized in early pregnancy (22-24 days). After ovariectomy, plasma concentrations of E I and E 2 were basal for i to 2 weeks. In contrast, slightly higher estrogen levels, which may be attributed to the ovaries, were found in intact pregnant monkeys. E 2 levels increased rapidly after this and exceeded those of E~ until the 5th month of gestation. From that time until parturition, E1 levels equaled or exceeded those of E2 in most instances. The pattern of P concentrations was similar to that observed in intact monkeys. Urinary chorionic gonadotropin (MCG) levels in ovariectomized monkeys were not significantly different from those found in normal pregnancies. Thus, the patterns for circulating El, E2 and P, as well as for the excretion of MCG, after ovariectomy were remarkably similar to those found in intact, pregnant rhesus monkeys, indicating minimal ovarian influence. INTRODUCTION The demonstration that ovariectomy of rhesus monkeys as early as the twenty-first day of gestation did not interfere with the normal course of gestation,
delivery of young, or lactation
(i), raised ques-
tions regarding the hormonal status of these primates.
More recently,
the finding that the corpus luteum of pregnancy undergoes rejuvenation shortly before parturition
in this species
lems with regard to understanding gestation.
(2) presented further prob-
the role of the ovaries throughout
The present report describes alterations in plasma levels
of estradiol-17~
(E2), estrone
(El) , and progesterone
excretion patterns of macaque chorionic gonadotropin of monkeys ovariectomized
Volume 25, Number 2
(P) and urinary (MCG) in a group
at 22-24 days of pregnancy.
~
~" ~
R
o
x ~
s
February,
1975
276
8
T
~, ~ o
x ~m
MATERIALS AND METHODS Five pregnant adult monkeys were bilaterally ovariectomized at 2224 days gestation using surgical procedures described previously (i). Details of mating and determination of pregnancy have been reported (3). Heparlnized blood samples ( 5 ml) were collected at intervals throughout pregnancy. Plasma was frozen at -10C until assayed. Radioimmunoassay methods for determination of plasma progesterone, estradiol-178, and estrone were described in (4). Twenty-four hr urine specimens were collected, extracted (3), and quantified for MCG activity in a biological assay as previously reported (5). Urine samples were obtained from 5 monkeys ovariectomlzed early in pregnancy. However, one female aborted on the 143rd day and data on plasma steroids from this animal were not included in this report. RESULTS Concentrations of P, El, and E~ were determined throughout pregnancy in the peripheral plasma of four rhesus monkeys which were ovariectomized in early gestation.
Except for a single value (monkey C143) at
the time of conception, El concentrations equaled or exceeded those of E2 during the first 3 weeks of gestation.
After ovariectomy, El and E2
abruptly declined to basal levels for a period of one to two weeks.
El
and E2 levels began rising between 35 to 40 days after conception but E2 concentrations exceeded those of El until the fourth or fifth month (Fig i and 3a).
At that time, El levels rose rapidly until they equaled
or exceeded those of E2 in the pre-partum period.
Levels of both estro-
gens declined markedly soon after parturition. Plasma P patterns in ovariectomized monkeys (Fig 2 and 3b) were similar to those previously reported for intact pregnant rhesus monkeys (3,6,7), although P levels in one animal (monkey 248) were markedly elevated for several days after ovariectomy.
Parturition was followed
by a rapid decline in P levels (Fig 2). Chorionic gonadotropin excretion in 24 hour urine samples from 7 normal and 5 ovariectomized monkeys are shown in Fig 4.
No significant
S
1000
"I" ~
1~.0
= : Est rodiol- 17/~ 0----0 Estrone
I
I)
ll
277
~ 686-V
Deli-i-, ~
800
o.
Ovorieclomy 2O0
~0 M
800[-
l
20 - -
40
60
80 I00 GESTATION (DAYS)
: Estrcld,ol- ;7~ o--- -o Eslrone
120
)40
160
)80
? 704-W
600 L
ery
p --d/
#0 M
800
¢
20
40
¢ £sTrodlOl"17~
c.---oE.,o.e
60
80 I00 GESTATpON(DAYS)
120
o
140
160
180
?CJ43
~
Da,~.,y
6OO
400
2OO ~p
~0 M
20
40
60
80 I00 GESTATION(DAYS)
120
140
160
180
Fig. i. Maternal peripheral plasma levels of estradiol and estrone in a series of rhesus monkeys before and after ovariectomy in early gestation
278
~
'~- 1=, : R o
i
-n~
Ovoriectomy
~og6v
w4
~2 Q I
I
~0 M
I
20
40
I
60
I
80 I00 GESTATION (DAYS)
Ovariect0my
I
I
I
120
140
I
160
180
? 704 W
i 6
~0 M
20
40
60
80 JO0 GESTATION (DAYS)
120
140
r60
180
9 cf43
----'6
~2 I
/
I
I
0
2'0
40
60
I
l
1
80 I00 GESTATION(DAYS)
I
120
I
L
140
~60
•
I
J80
Fig. 2. Maternal peripheral plasma levels of progesterone in a series of rhesus monkeys before and after ovariectomy in early gestation.
8
I " ]El ] B , O
I
I)
ll
279
ISG7 1400 I
(~248
12OO~-
ISIAl
Oebvery
~. ~ Esfr0d~01"17~ O- ---0 Eslrone
/
I I
,ooo F
~1 I
oooF
of
........
400
//
R
~'o
M
so
,~
GESTATION(DAYS)
/
,2o,;,:o,so,~,,o
' "O IB
Fig. 3a. Plasma levels of estradiol and estrone before and after ovariectomy in early gestation.
23;2
~248
I0 Parturit~n
8
l
/
~6
4
(X~rec~om I
2O
40
60
I
I
I
80 I00 120 GESTATION (DAYS)
I
I
I
140
160
180
Fig. 3b. Plasma levels of progesterone before and after ovariectomy in early gestation.
S
280
~
~" ~R, O I
~'j~
differences in hormone output were found after ovariectomy throughout the limited period of chorionic gonadotropin excretion.
300
•
[] --
Intocl Monkeys Ovo.ectomlzed Monkeys
25O
~200 ~ ~50 Q_
ioo N 50 16
17
18
19 20 21
22
23
24
25 26
27
28
29
30
31
32
DAY OF PREGNANCY
Fig. 4. Daily urinary MCG excretion ~HCG equivalents) in a series of 7 intact and 5 ovariectomized rhesus monkeys. Ovariectomy between 22nd to 24th day of pregnancy.
DISCUSSION In normal pregnant animals in this colony, both E2 and El decline tc levels approximating 50 pg/ml plasma at about 30-35 days after conceptiol This diminution is followed by a rise in E2, with Ez remaining at low cot centrations for the ensuing 2 months (3,4,7).
The low levels of Ez and
E2 found in intact animals, as compared with the almost complete absence of measurable estrogens shortly after ovariectomy, indicate that the ovaries are the principal source of these estrogens up to about 5 to 6 weeks of pregnancy.
Except for the decrease in plasma E I and E2 soon
after ovariectomy, the pattern of estrogen production is similar to that of intact pregnant animals at comparable stages of gestation.
Data fro=
the present study, as well as previous reports (3,4,8), suggest that th~
~
TXZ~.OX]t~m
281
feto-placental complex assumes the major role in estrogen production at about 6 weeks gestation.
After the 5th or 6th week, a rise in plasma E2
concentration occurs and continues until term.
El, on the other hand,
undergoes a slow but continuous rise which is accelerated during the 4th or 5th month.
Results presented here demonstrate
in estrogen level are independent of the ovaries.
that these increases In a related study of
fetectomized monkeys, we have shown that the fetus is the major source of E I and E2 or their precursors during the last 3 months for E2 and, the final month prior to parturition for El (4). Although one monkey exhibited a sharp rise in plasma P levels shortly after ovariectomy,
the usual pattern for P production remained similar
to that previously reported for intact animals
(3,6,7).
It should be
noted that there is a peak in plasma P levels in most intact monkeys during the 4th or 5th week of gestation study were ovariectomized
(3,6,7) and that the monkeys in this
about one week before that time.
Despite ova-
riectomy early in the 4th week, rising P levels were observed in all four monkeys during the week in~nediately
following surgery.
This confirms an
earlier report suggesting a predominantly placental origin for P at this stage of pregnancy
(6).
The rise in E2 levels which occurs several days
after this progesterone peak can be conclusively dissociated from the ovaries on the basis of the present experiments and shown
to be of fetal
origin (4). The transient rise and fall in plasma P in the presence or absence of the ovaries during weeks 4 and 5 could possibly arise from stimulation of placental P synthesis by MCG, since MCG levels are at maximum several days before the rise in P is observed.
We have presented data
282
~
T ~'
~ o
x mmm
showing that ovariectomy had no measurable influence on the rate of excretion of MCG. The rapid decline in P levels after parturition confirms the earlier studies which emphasized the dominant role of the placenta in P production after the third week in pregnancy.
It appears that failure
to maintain pregnancy after ovariectomy earlier than the 3rd week in gestation, unless exogenous progesterone is administered, is related to the inability of the placenta to provide an adequate quantity of P (9). In conclusion, present findings show that, except for a decrease in estrogen levels shortly after ovariectomy, the general pattern observed for El, E2 and P concentrations in maternal plasma throughout gestation cannot be differentiated from those found in intact pregnant rhesus monkeys and confirm the dispensability of the ovaries for maintenance of pregnancy in this species. ACKNOWLEDGMENTS We gratefully acknowledge the expert technical assistance of Don Barber, Charles Turner, and Louise Metz. REFERENCES i. 2. 3. 4. 5. 6. 7. 8. 9.
Tullner, W. W. and Hertz, R., ENDOCRINOLOGY 78, 1076 (1966). Treloar, O. L., Wolfe, R. C. and Meyer, R. K., ENDOCRINOLOGY 91, 665 (1972). Hodgen, G. D., Dufau, M. L., Catt, K. J. and Tullner, W. W., ENDOCRINOLOGY 91, 896 (1972). Tullner, W. W. and Hodgen, G. D., STEROIDS 24 (in press). Nixon, W. E., Hodgen, G. D., Niemann, W. H., Ross, G. T. and Tullner, W. W., ENDOCRINOLOGY 90, 1105 (1972). Neill, J. D., Johansson, E. D. B. and Knobil, E., ENDOCRINOLOGY 84, 45 (1969). Hodgen, G. D. and Tullner, W. W. Abstract 56th ANNUAL MEETING of the ENDOCRINE SOC. p. A-248 (1974). Bosu, W. T. K., Johansson, E. D. B., and Gemzell, C. ACTA ENDOCR. (Kbh.) 75, 601 (1974). Meyer, R. K., Wolf, R. C. and Arslan M., PROC. 2nd INT. CONGR. PRIMAT. ATLANTA, GA. 1968, ed. H. O. Hofer, Vol 2, Karger, Basel/New York, 1969, p. 30.
