Reduction of 5-day cycle length of female rats by treatment with bromocriptine

1983 ◽  
Vol 97 (1) ◽  
pp. 83-89 ◽  
Author(s):  
P. van der Schoot ◽  
J. Th. J. Uilenbroek
Keyword(s):  
Cycle Length ◽  
Female Rats ◽  
Corpora Lutea ◽  
Normal Numbers ◽  
Ovarian Weight ◽  
Follicular Maturation ◽  
Large Numbers ◽  
Luteal Tissue ◽  
Pattern Characteristic ◽  
High Concentrations

Rats with 5-day ovarian cycles were injected daily with 1 mg bromocriptine. This treatment resulted in a change of cycle length from 5 to 4 days and a rapid increase in ovarian weight. The increase in ovarian weight resulted from the accumulation of large numbers of corpora lutea. Normal numbers of corpora lutea were formed during each cycle but luteal bodies did not disappear subsequently. Luteolysis affected only minor foci of luteal tissue and the majority of luteal tissue remained histologically intact throughout the further period of study. The reduction of cycle length from 5 to 4 days occurred when bromocriptine was administered from the day of ovulation only. If treatment was commenced at a later time during the cycle it was not effective. Treatment with bromocriptine appeared to affect the concentrations of progesterone in the blood during dioestrus. During treatment the rats showed the pattern characteristic for 4-day cycles: typically, the high concentrations of progesterone on the day after metoestrus remained absent. These data suggest (1) that the latter part of the production of progesterone during dioestrus by 'non-functional corpora lutea' is dependent on prolactin and (2) that prolongation of high progesterone production after metoestrus plays an important role in changing the length of the cycle from 4 to 5 days. Treatment with bromocriptine did not significantly affect the rate of maturation of follicles destined for the next ovulation. It is possible that follicular maturation is not among the critical variables which determine whether normal ovulatory cycles will last for 4 or 5 days.

Luteolytic and antiluteolytic effect of the antiprogestagen RU486 in pseudopregnant rats

1995 ◽  
Vol 145 (3) ◽  
pp. 449-454 ◽  
Author(s):  
J Th J Uilenbroek ◽  
P van der Schoot ◽  
J A M Mattheij ◽  
J J M Swarts
Keyword(s):  
Plasma Concentrations ◽  
Early Morning ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Corpora Lutea ◽  
Serum Progesterone ◽  
Early Afternoon ◽  
Two Generations ◽  
Pituitary Glands ◽  
High Concentrations

Abstract To study the effects of the antiprogestagen RU486 on luteal activity in pseudopregnant rats, adult female rats made pseudopregnant by sterile copulation were given daily injections with oil vehicle or with RU486 (2 mg/day) either during the entire period of pseudopregnancy (day 1 till day 14) or during the second half of pseudopregnancy (day 8 till day 14). Blood was taken every other day to measure serum concentrations of progesterone. At autopsy, on day 15, the weights of ovaries, isolated corpora lutea and pituitary glands were recorded. In a second study using the same experimental protocol, blood was taken via a jugular vein cannula on days 8, 9, 10 and 11 after induction of pseudopregnancy; on each of these days blood samples were taken at 0700, 0800 and 0900 h, and at 1700, 1800 and 1900 h to measure plasma concentrations of prolactin, LH and progesterone. Administration of RU486 from day 1 of pseudopregnancy onwards had no effect on the increasing concentrations of serum progesterone during the first half of pseudopregnancy. Thereafter progesterone concentrations increased further in RU486-treated rats whereas they decreased in oil-treated pseudopregnant rats. Administration of RU486 from day 8 of pseudopregnancy onwards resulted in a decline in progesterone concentrations in serum on day 10 followed by ovulation on day 11. Plasma LH concentrations in rats treated with RU486 from day 1 of pseudopregnancy were higher than those in oil-treated rats on days 8, 9, 10 and 11. Treatment from day 8 of pseudopregnancy resulted in low LH concentrations at days 8 and 9 and the presence of a preovulatory surge of LH on the afternoon of day 10 (day of pro-oestrus). Plasma concentrations of prolactin measured in oil-treated rats showed two daily surges of similar magnitude in the morning and afternoon of days 8, 9, 10 and 11. In animals treated with RU486 from day 8 onwards, the afternoon surge on day 9 and the morning surge on day 10 were absent. This demonstrated that the luteolytic effect of RU486 when given during the second part of pseudopregnancy is due to a blockade in the afternoon surge of prolactin on day 9. In animals treated with RU486 from day 1 of pseudopregnancy onwards, prolactin in the early morning samples was low, while prolactin in the afternoon samples was highly elevated. At autopsy on day 15, the weights of ovaries, corpora lutea and pituitary glands in animals treated with RU486 from day 1 were larger than those in oil-treated rats; this is in line with an increased secretion of prolactin. In contrast, in animals treated with RU486 from day 8, pituitary weight was not elevated and the increase in ovarian weight was due to the presence of two generations of corpora lutea. In conclusion, whether or not RU486 is luteolytic in pseudopregnant rats depends on the time of administration: injection during the second half of pseudopregnancy inhibits prolactin secretion and induces luteolysis, while administration during the early phase of pseudopregnancy results in high concentrations of prolactin in the early afternoon and therefore prevents luteolysis. Journal of Endocrinology (1995) 145, 449–454

Postovulatory steroidogenesis after PMS-induced ovulation in immature female rats

1981 ◽  
Vol 241 (3) ◽  
pp. E221-E225 ◽  
Author(s):  
K. Taya ◽  
G. S. Greenwald
Keyword(s):  
Serum Levels ◽  
Female Rats ◽  
Corpora Lutea ◽  
Adult Rats ◽  
Rat Serum ◽  
Follicular Maturation ◽  
Adult Rat ◽  
Serum Lh

Thirty-day-old rats given a single subcutaneous injection of 5 IU pregnant mare serum gonadotropin (PMS) at 0900 h ovulated on the morning of day 33 (= estrus). However, the second ovulation did not occur until 9.4 days later. To determine the mechanism responsible for the delay in the second ovulation, in vivo and in vitro determinations of steroid and peptide hormones were compared between PMS-primed immature rats and adult cyclic rats. In PMS-primed rats, the corpora lutea (CL) produced progesterone for 2 days longer (until day 36) than the CL of the adult rat. Serum levels of 20 alpha-dihydroprogesterone, testosterone, and estradiol in PMS-primed rats were significantly lower than the corresponding values in adult rats. Serum LH was consistently lower in the PMS-primed rats. An increase in serum FSH occurred on days 36–37, which may be responsible for maturation of the follicles destined to ovulate at the second ovulation. On day 37, the nonluteal ovary of the PMS-primed rats also began to produce in vitro appreciable amounts of testosterone and estradiol. These findings suggest that the greater levels of prolactin and/or low levels of luteinizing hormone during estrus in PMS-primed rats may be responsible for the prolonged secretion of progesterone by the CL. This in turn inhibits follicular maturation, indirectly by lowering serum LH, which is reflected in reduced ability of the follicles in vitro to produce testosterone and estradiol until the CL regress.

THE EFFECT OF PROMETHAZINE AND CLOMIPHENE ON GONADOTROPHIN SECRETION IN THE RAT

1971 ◽  
Vol 49 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Y. KOCH ◽  
S. DIKSTEIN ◽  
E. SUPERSTINE ◽  
F. G. SULMAN
Keyword(s):  
Mechanism Of Action ◽  
Clomiphene Citrate ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Corpora Lutea ◽  
Ovarian Weight ◽  
Gonadotrophin Secretion ◽  
Small Doses ◽  
Releasing Factors ◽  
Higher Doses

SUMMARY Promethazine and promethazine sulphoxide selectively inhibited gonadotrophin secretion in female rats. The effects obtained were: decrease in ovarian weight, reduction in the number of follicles and corpora lutea in the ovary, prolongation of the oestrous cycle and reduced amounts of gonadotrophin-releasing factors in the hypothalamus. Very small doses of clomiphene citrate (1–100 ng/kg) increased gonadotrophin secretion in female rats, as shown by an increase in ovarian weight, increase in the number of corpora lutea, shortening of the oestrous cycle and increased amounts of gonadotrophin-releasing factors in the hypothalamus. Higher doses of clomiphene citrate (1 μg—2 mg/kg) produced the well-known inhibition of gonadotrophin secretion. The possible mechanism of action of these drugs is discussed.

EFFECTS OF OESTRADIOL BENZOATE ON CORPORA LUTEA IN RATS BEARING PITUITARY AUTOGRAFTS

1969 ◽  
Vol 60 (2) ◽  
pp. 184-198 ◽  
Author(s):  
Sidney J. Stolzenberg ◽  
Robert G. Eggert ◽  
Wayne H. Linkenheimer
Keyword(s):  
Pituitary Gland ◽  
Term Treatment ◽  
Female Rats ◽  
Corpora Lutea ◽  
Short Term Treatment ◽  
Subcutaneous Injections ◽  
Ovarian Weight ◽  
Long Term Treatment ◽  
Oestradiol Benzoate ◽  
Hypophysectomized Rats

ABSTRACT Female rats received pituitary autotransplants beneath the kidney capsule at 11 to 12 weeks of age or were hypophysectomized only at the metoestrous stage of the cycle. Subcutaneous injections of oestradiol benzoate (OB) were started 30 to 40 days following surgery in the first 3 experiments. In Experiments 1 and 2, Series 1 injections consisted of 50, 50 and 25 μg of OB given subcutaneously on days 0, 3 and 5. Series 2 injections were the same as Series 1 but given on days 16, 19 and 21. Pituitary grafts were removed from half of the rats on day 15 in Experiment 1. Ovarian weights were obtained on day 28. In Experiment 3, the dose of OB was raised to 100 μg per injection giving a total of 300 μg for each series. In Experiment 4, hypophysectomized rats without pituitary autotransplants were given Series 1 and 2 OB injections at the level of 125 μg per series. In Experiment 5, subcutaneous injections of OB were started 5 to 7 days following pituitary autotransplant. Rats were injected daily with 50 μg for 5, 10, 20, 40 and 80 days, with autopsies following 4 or 5 days after the last injection. In Experiment 6, 50 μg was injected daily in hypophysectomized rats without pituitary transplants for 5 and 20 days. The immediate effect of OB injections into rats bearing pituitary autografts was a significant (P < 0.01) increase in ovarian weight. Long term treatment (> 40 days) caused a significant (P < 0.05) decrease in ovarian weight. Short term treatment followed by a 23 or 35 day period of no treatment gave an even greater decrease in ovarian weight (P < 0.01). Hypophysectomized rats showed no effect on ovarian weights with similar OB treatments, indicating the importance of the pituitary gland in this response. Removal of the autotransplanted pituitary gland 10 days after the first series was completed, had no apparent effect on regression of the corpora lutea. There was no effect on adrenal weight in any of the experiments. It is suggested that oestrogens initiate a process which ultimately results in luteal regression in rats bearing pituitary autografts.

Reproduction in the mountain possum, Trichosurus caninus (Ogilby), in captivity

1973 ◽  
Vol 21 (3) ◽  
pp. 321 ◽  
Author(s):  
MJ Smith ◽  
RA How
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Hormone Secretion ◽  
Vaginal Smear ◽  
Corpora Lutea ◽  
Ovarian Weight ◽  
Luteal Cells ◽  
In Captivity ◽  
Luteal Tissue ◽  
The Mean

Reproduction was studied in eight female T. caninus held in captivity in Armidale, N.S.W., for up to 5 yr. Oestrus was diagnosed from the vast increase in epithelial cells in the vaginal smear, post-oestrus being detected by the appearance of many leucocytes and of some elongate epithelial cells. The mean of 17 oestrous cycles was 26.4+- 1.0 days and the mean of 10 gestation periods was 16.2+-0.2 days. The teats evert and the female first ovulates at the end of her 2nd year, but no captive female gave birth till near the end of her 3rd year. In the anatomy of the uteri and vaginae, T. caninus resembles T. vulpecula but the ovaries of T. caninus are markedly distinguished by the presence of up to seven large corpora lutea. Although the weight of the luteal tissue may contribute as much as 83.9 % of the total ovarian weight, there is no evidence from the uteri that these large corpora lutea are functional in hormone secretion. The luteal cells are large but vacuolated and are separated by a well developed network of connective tissue. As the corpora lutea persist throughout the life of the animal, it is suggested that their number be used to indicate the maximum age of the animal.

THE EFFECT OF VASOPRESSIN AND OXYTOCIN ON THE FUNCTION OF PITUITARY AUTOGRAFTS IN RATS

1968 ◽  
Vol 58 (1) ◽  
pp. 101-115 ◽  
Author(s):  
Sidney J. Stolzenberg ◽  
Lloyd C. Faulkner ◽  
William Hansel
Keyword(s):  
Female Rats ◽  
Adrenal Weight ◽  
Corpora Lutea ◽  
Zona Fasciculata ◽  
Obvious Effect ◽  
Kidney Capsule ◽  
Ovarian Weight ◽  
Hypophysectomized Rats ◽  
Secretory Pattern ◽  
Thyroid Histology

ABSTRACT Mature cycling female rats received pituitary autografts beneath the kidney capsule or were hypophysectomized only. Intraperitoneal injections of vasopressin at the level of 3 or 4 IU twice daily into rats with autografts caused an increase in adrenal weights after 45 (P < 0.01) and 70 (P < 0.01) days of treatment. There was an increase in the width of the combined zona fasciculata and reticularis observed after 70 days (P < 0.01). These results were accompanied by a decrease in ovarian weight after 45 (P < 0.01) and 70 (P < 0.01) days of vasopressin treatment. The decrease in ovarian weight was due to histologic regression of corpora lutea. Similar injections of vasopressin into hypophysectomized rats for 45 days were without effect on the ovaries or adrenals. Intraperitoneal injections of 3 or 4 IU oxytocin twice daily for 45 days in rats bearing pituitary autografts had no effect on adrenal weight or histology and caused a non-significant decrease in ovarian weight but had no effect on ovarian histology. However, after 70 days of treatment with oxytocin, there was an increase in adrenal weight (P < 0.01) which could not be attributed to an effect on the zona fasciculata-reticularis. There was a decrease in ovarian weight (P < 0.01), similarly attributable to a regression of the corpora lutea. None of the treatments affected uterine weight or histology or thyroid histology in either rats with pituitary autografts or in animals that were simply hypophysectomized. None of the treatments had any obvious effect on the cytologic appearance of the pituitary graft. It is suggested that effective treatments modified the secretory pattern of pituitary grafts.

Ovarian response to gonadotrophins after pretreatment with diethylstilbestrol

1963 ◽  
Vol 204 (6) ◽  
pp. 1023-1027 ◽  
Author(s):  
B. D. Smith ◽  
J. T. Bradbury
Keyword(s):  
Ovarian Response ◽  
Female Rats ◽  
Corpora Lutea ◽  
Follicular Growth ◽  
Immature Female ◽  
Ovarian Weight ◽  
Hypophysectomized Rats ◽  
Follicular Stimulation ◽  
Prior Administration ◽  
Intact Rats

Hypophysectomized or intact immature female rats were given follicle-stimulating hormone (FSH), pregnant mare's serum gonadotrophin (PMS), human chorionic gonadotrophin (HCG), or luteinizing hormone (LH) for 3 days, with or without prior administration of diethylstilbestrol for 2 days. Priming with estrogen augmented the ovarian weight response produced by FSH or PMS in both hypophysectomized and intact animals. In contrast, estrogen pretreatment enhanced ovarian growth in intact rats given HCG or LH, but not in hypophysectomized animals similarly treated. Longer periods of priming also failed to augment the ovarian response to HCG in hypophysectomized rats. The ovaries of intact rats given diethylstilbestrol and FSH contained many corpora lutea, whereas luteinization was never noted in hypophysectomized animals similarly treated. Ovarian weight augmentation in the latter was due to enhanced follicular growth throughout the ovary. Estrogen and HCG produced cystic, luteinized follicles in intact rats, in contrast to the lack of such follicular stimulation in hypophysectomized animals. It is concluded that estrogen increases the ovarian response to gonadotrophins by 1) directly stimulating granulosal proliferation, and 2) effecting the release of endogenous gonadotrophins from the pituitary gland.

Oxytocin can affect follicular development in the adult mouse

1985 ◽  
Vol 108 (2) ◽  
pp. 273-276 ◽  
Author(s):  
G. Robinson ◽  
J. J. Evans ◽  
M. E. Forster
Keyword(s):  
Adult Mouse ◽  
Follicular Development ◽  
Antral Follicle ◽  
Normal Adult ◽  
Corpora Lutea ◽  
Antral Follicles ◽  
Follicular Maturation ◽  
Ovarian Histology ◽  
Large Numbers ◽  
Experimental Group

Abstract. Injection of oxytocin into normal adult cycling mice caused alterations in ovarian histology. Oxytocin was administered early on the day of pro-oestrus and it induced the appearance of large numbers of corpora lutea by late pro-oestrus, suggesting oxytocin stimulated ovulation. When mice were examined very early on the day of normal oestrus the ovarian population of follicles was different in the experimental group from that in the control mice, there being increased numbers of preantral and antral follicles in treated animals. As oxytocin can cause an alteration in the timing of follicular maturation and ovulation processes study of communications between the adenohypophysis and areas containing oxytocin might be important for understanding physiological details of ovulation. The relative times at which, for instance, antral follicle and corpora lutea populations increased suggested that oxytocin might have more than one activity which affects ovarian behaviour.

Normal and blocked pregnancy in the collared lemming: morphometrical and histological changes

1989 ◽  
Vol 67 (6) ◽  
pp. 1363-1371 ◽  
Author(s):  
Nicolle P. Rathmann ◽  
Frank F. Mallory
Keyword(s):  
Corpora Lutea ◽  
Uterine Weight ◽  
Wild Stock ◽  
Histological Changes ◽  
Full Size ◽  
Ovarian Weight ◽  
Large Numbers ◽  
Supportive Role ◽  
Dicrostonyx Groenlandicus ◽  
Very High

Normal and blocked pregnancy were studied in the collared lemming, Dicrostonyx groenlandicus, in the laboratory with individuals bred from wild stock caught at Eskimo Point, N.W.T. Morphometrical changes (corpora luteal area, ovarian weight, uterine weight, fetal crown–rump lengths, spleen and adrenal weights) during normal and blocked pregnancy were documented and found to be similar to those of other microtines. Mean maximum corpora luteal area, and ovarian and uterine weights increased continuously throughout gestation, as did the fetal crown–rump lengths. Spleen and paired adrenal weights increased similarly; however, they were not significantly different when corrected for body weight. Ovulation occurred between 9 and 12 h post coitum, as evidenced by the presence of ovulated follicles with stigmata, and luteinization was observed within 24 h. No identifiable differences were observed in the histology of corpora lutea and corpora albicantia of normal and blocked females although significant differences in size occurred. Accessory luteal structures (accessory corpora lutea and luteinized follicles) were found in very high numbers in this species compared with other microtines, peaking by day 4 post coitum and declining in number and size towards the end of gestation. It is concluded that the accessory luteal structures function in a supportive role to the corpora lutea of pregnancy during the early stages of gestation but undergo atrophy towards parturition, when the corpora lutea of pregnancy reach their full size and functional capacity. The presence of large numbers of accessory luteal structures and the similarity of histology between ovarian structures in normal and blocked pregnancy makes the identification of these conditions in the field impractical at present.

Localization of oxytocin and neurophysin in baboon (Papio anubis) corpus luteum by immunocytochemistry

1986 ◽  
Vol 113 (4) ◽  
pp. 570-575 ◽  
Author(s):  
Firyal S. Khan-Dawood
Keyword(s):  
Corpus Luteum ◽  
Rabbit Serum ◽  
Corpora Lutea ◽  
Positive Staining ◽  
Normal Rabbit Serum ◽  
Fallopian Tubes ◽  
Papio Anubis ◽  
Luteal Cells ◽  
Luteal Tissue ◽  
Immunocytochemical Reaction

Abstract. Immunoreactive oxytocin is detectable in the corpora lutea of women and cynomolgus monkeys by radioimmunoassay. To localize the presence of oxytocin and neurophysin I in ovarian tissues of subhuman primates, three corpora lutea and ovarian stromal tissues and two Fallopian tubes obtained during the menstrual cycle of the baboon and decidua from two pregnant baboons were examined using highly specific antisera against either oxytocin or neurophysin I and preoxidase-antiperoxidase light microscopy immunohistochemistry. Oxytocin-like as well as neurophysin I-like immunoreactivities were found in some cells of all the corpora lutea only, but could not be demonstrated in ovarian stromal tissues, Fallopian tubes and decidua. Specificity of the immunocytochemical reaction was further confirmed by immunoabsorption of the antiserum with excess oxytocin or neurophysin, after which the immunoreactivities for both oxytocin and neurophysin in the luteal tissue were negative. Similar controls using normal rabbit serum gave no positive staining for either oxytocin or neurophysin. Counterstaining of the positive immunoreactivities for oxytocin and neurophysin I with Mayer's haematoxylin and eosin demonstrated clearly that the oxytocin and neurophysin I appeared as granular material mainly within the cytoplasm of the luteal cells. The localization of immunoreactive oxytocin and neurophysin I in the corpus luteum of the baboon demonstrates directly the presence of these two neurohypophysial peptides within primate luteal cells and suggests their local production.

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