Endocrinol.

1975, 22 (3),

Japon.

261•`264

NOTE The

Size

*NOBORU

of

the

Corpus Luteum and Pregnancy

MIYAGAWA

, KUNIO AND

during Pseudopregnancy in the Rat

NOGUCHI,

MOTOI

RYOHEI

OKAMOTO

SAITO

Department of Obstetrics and Gynecology, Tokyo Medical and Dental University, Yushima, Tokyo 113

Synopsis The stages

corpus

of

1.0•}0.10mg, 2 of

luteum

on

respectively.

days

The

exposure on

days

of

14

of

secreted

more,

it

larger

than

was

continued

14

of

in

the

corpus

that

pregnancy,

14,

14 on

the

stage

of

was

larger

size

ovary

seems

of

the

was

10

that As

further there

when

was

the

size

of

14

on

day

of

of

the

was

days

secreted

corpus

luteum This

of

of of

corpus on

placental

pregnancy. 20

of from

pregnancy.

Furtherpregnancy

placental

remarkable

in

10-15 drive

that

the

day

pregnancy,

days

amounts

secretion a

of

placenta

of

large

and

size than

was

on

to

average

ovariectomy

indispensable

on

9-10

of

20

thought

that

days

luteum

and

larger

average

various

lutea

decrease performed

maintaining

was lactogen in on

the day

pregnancy

rat.

Pregnancy could be maintained in hypophysectomized pregnant rats, when hypophysectomy was performed before the 12th day of gestation, by providing progesterone treatment and failed without it (Alloiteau, 1957; Rothchild, 1960). Pseudopregnancy could also be induced and maintained in the regular cyclic rat with progesterone treatment (Rothchild and Schwartz, 1965). Progesterone is secreted from the corpus luteum in response to prolactin stimulation Received * present

The

on

days

suggests

considered

is

presence

corpus

pregnancy

luteum

demonstrate

that

14,

corpus

be

the

corpora

4.37•}0.50mg

9-10,

to

at

these

diestrus

of

The

than

the

days

prolactin.

pregnancy.

weighed

of and

the 2

to

pregnancy. 20

was

size

tendency

between of

which

of

day

a

to

placenta

the

day

day

fetuses

the

that

of

this

of day

to

had

attributed

from noted

after of

be

on

luteum

and this

on size

that

pregnancy

rats

average

3.69•}0.36mg,

average

the of

might

lactogen

the than

of

by

Dawley The

pseudopregnancy,

larger

pregnancy

phenomenon

number

that

9-10

lactogen

day

of

pseudopregnancy

placental on

10-15

was

prolonged

Sprague

pregancy.

1.90•}0.25mg,

fact

pseudopregnancy

10-15

mature and

1.61 •}0.69mg,

diestrus,

luteum

in

pseudopregnancy

for publication adress:

August

Department of Gynecology Toritu komagome hospital Honkomagome, Bunkyo-ku,

30, 1974.

and Obsterics Tokyo,

113

in the rat. During pseudopregnancy, prolactin is secreted from the pituitary gland. During pregnancy, in addition to prolactin secreted from the pituitary gland, the placenta secretes lactogenic hormone which has the luteotrophic activity. Therefore, it seems reasonable to assume that the change in the size of the corpus luteum reflects the luteotrophic activity of these prolactin and placental lactogen. This experiment was carried out to see how the corpus luteum changed in weight during pseudopregnancy and pregnancy in the rat.

262

MIYAGAWA

et al.

Endocrinol. June 1975

Japon.

luteotrophic activity of prolactin. The luteotrophic activity of prolactin in the rat was Materials

and

Methods

Mature Sprague Dawley female rats were used. Five animals were kept in a cage in an air conditioned room with controlled lighting, which provided 14 hours of light (5 A.M. to 7 P.M.) and 10 hours of darkness daily. HMF solid food (Oriental Enzyme Industry Co. Ltd.) and water were supplied ad libitum. Vaginal smears were checked daily throughout the experiments. All the rats used in the experiment showed at least three consecutive regular 4 or 5 day estrus cycles prior to use. Pseudopregnancy (psp.) was induced by mechanical stimulations of the cervix on successive proestrus and estrus days. Since psp. is the condition of a prolonged physiologically active luteal phase without implantation, we defined psp. as the diestrus period lasting for more than 9 days in the paper. The first day of diestrus following cervical stimulations was designated day 1 of psp., and day 0 of pregnancy (preg.) was designated the day when sperms were found in the smear. Ovariectomy was performed on day 2 of diestrus, on day 10 or 11 of psp., on day 14 or 15 of psp., on day 9 or 10 of preg., on day 14 of preg., and on day 20 of preg. All ovaries were fixed with Bouin's fluid immediately after being removed. Each corpus luteum of the particular set was dissected and cleaned of as much non-luteal tissue as possible with the aid of a pair of very fine curved forceps and a knife fashioned from a dental pick after being fixed for 7 days in Bouin's fluid, and weighed on a librar balance (Shimazu Co., Ltd.), to the nearest 0.01 mg, after being blotted by clean filter paper. The mean corpus luteum weight for each rat was then calculated from the weight of the total set and number of corpora lutea in the set (Rothchild and Schwartz, 1965). In animals ovariectomized on day 14 of preg., number of fetuses per one rat was counted both at the time of ovariectomy and on day 20 of preg. in the same rat.

Results

and

firstshown by Astwood (Astwood,1941) and Evans et al. (Evans et al., 1941). In psp. rats, corpora lutea did not regress, and continued to grow by luteotrophic hormone (Rothchild, 1965a), and reached the maximum size by day 14 (Rothchild and Schwartz, 1965). As shown in Table 1, there were a few psp. rats which showed the luteal phase for more than 14 days after the cervical stimulation. Four and 1 of those rats showed the luteal phase for 14 and 15 days, respectively. The average size of the corpus luteum of these rats and that on days 10-11 of psp. rats was 1.62+0.33mg and 1.61+0.54mg (Mean+ SD), respectively. Since there was no significant difference between the size of the corpus luteum on days 10-11 of psp. and that on days 14-15 of psp., the data were combined. The average size of the corpus luteum on days 10-15 of psp. was 1.61+ 0.69mg. The average number of corpora lutea in one rat on days 10-15 of psp. was 11.5+2.0. The average size and number of the corpus luteum on day 2 of Table 1.

Average size of the corpus luteum (mg)/ rat.(Number of corpora lutea in one rat)

Discussion

In the regular cyclic rat, the growth of the corpus luteum and progesterone secretion were low and lasted for no more than 4 or 5 days (Rothchild, 1965a). Following the mechanical stimulation of the cervix, their growth was accelerated and its secretory activity increased and lasted for approximately 15 days. This phase of increased luteal activity seemed to result from the

No significant difference between *2 and *3 Significant difference between *1 and *4. (p

The size of the corpus luteum during pseudopregnancy and pregnancy in the rat.

The corpus luteum in mature Sprague Dawley rats was weighted at the various stages of pseudopregnancy and pregancy. The average size of these corpora ...
472KB Sizes 0 Downloads 0 Views