Effect of Bovine Endometrial Extracts, Vasopressin and Oxytocin on the Duration of Pseudopregnancy in Hysterectomized and Intact Rats

Malven, P.V.; Hansel, William

doi:10.1530/jrf.0.0090207

Cited by 12 publications

(4 citation statements)

References 20 publications

(20 reference statements)

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“…Table 1 summarizes the experiments in which prolactin was administered to intact and hysterectomized rats during pseudopregnancy. The mean duration of pseudopregnancy in intact and hysterectomized controls agrees well with the findings of previous investigations (Malven & Hansel, 1965). Prolactin admini¬ stered once or twice daily to intact rats significantly lengthened (by 2 to 3 days, prolactin is administered to hypophysectomized rats possessing only non¬ functional corpora (Malven & Sawyer, 1966a).…”

Section: Introductionsupporting

confidence: 89%

A Mechanism Antagonizing the Luteotrophic Action of Exogenous Prolactin in Rats

Malven¹,

Hansel²,

Sawyer³

1967

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Summary. The luteotrophic action of injected prolactin appears to be antagonized by an endogenous luteolytic mechanism to such an extent that the functional life-span of the corpora lutea cannot be lengthened more than 3 days beyond that of the non-injected control. This type of antagonism was seen in both intact and hysterectomized pseudopregnant rats and in lactating rats deprived of their litters. The antagonism was not observed in hypophysectomized rats, in which prolactin injections maintained functional corpora lutea for at least 20 days after ovulation. These results suggest the existence of a hypophysial hormone capable of antagonizing endogenous as well as exogenous prolactin.Hysterectomy may affect the timing of the luteolytic mechanism, but the latter seems to operate effectively in the absence of uterine stimuli. Luteolysis is apparently inhibited during lactation, but removal of the suckling stimulus results in a prompt activation of the process.In control experiments with untreated lactating rats, litter removal 8 or 12 days post partum terminated luteal secretory function on Day 14 regardless of when the litters were removed. These results suggest that 7-day-old corpora lutea of lactation respond less quickly than 11-day\x=req-\ old corpora to the endogenous hormonal alterations resulting from litter removal.

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Section: Introductionsupporting

confidence: 89%

A Mechanism Antagonizing the Luteotrophic Action of Exogenous Prolactin in Rats

Malven¹,

Hansel²,

Sawyer³

1967

Reproduction

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“…Vaginal cycles averaged 20-6 and 20-4 days for the rats injected with ether-soluble extracts and lyophilized homogenates, respectively. These data are in agreement with those of Malven & Hansel (1965) who failed to demonstrate a luteolysin in pseudopregnant rats given aqueous and ether extracts of bovine endome¬ trium. This investigation was supported by funds provided in Grant HD-00392 from the National Institutes of Health.…”

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confidence: 92%

Effect of Parabiosis or Uterine Extracts on Pseudopregnancy in Hysterectomized Rats

Kiracofe¹,

Spies²

1966

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Regression of the corpora lutea was hastened in hysterectomized-pseudopregnant rats by parabiotic union with ovariectomized partners. Hysterectomized-pseudopregnant rats paired either with hysterectomized-pseudopregnant or with normal cycling partners had periods of pseudopregnancy similar in length to those in unpaired hysterectomized-pseudopregnant control females. Injections of ether-soluble extracts or of lyophilized homogenates of oestrous rat uteri did not shorten pseudopregnancy in hysterectomized rats.The technique of parabiosis (Bunster & Meyer, 1933) was employed to test for presence of a luteolysin from normal or ovariectomized rats that could cross the parabiotic union and influence the life-span of corpora lutea in pseudopregnant or hysterectomized-pseudopregnant partners. Sprague-Dawley females, 60 to 80 days old, were paired as follows: In Group 1, rats ovari¬ ectomized in di-oestrus were combined 4 or 5 days later with intact pseudo¬ pregnant ones which were in oestrus (Day 1) at the time of the operation; in Group 2, intact rats in oestrus were combined with hysterectomized-pseudo¬ pregnant ones on Day 4 or 5; in Group 3, pseudopregnant females hysterecto¬ mized immediately before parabiosis on Days 3, 4 or 5 were combined with rats ovariectomized 4 or 5 days previously; and in Group4, both pseudopregnant partners were hysterectomized and paired on Day 5. Pseudopregnancy was induced by cervical stimulation with a glass rod at late pro-oestrus or early oestrus. Rats showing vaginal cornification before Day 7 were discarded. Several of the largest corpora lutea in the hysterectomized-and intact-pseudopregnant partners were marked with India ink before joining, using the method described by Spies, Gier & Wheat (1964). Most rats were killed on the day after the first vaginal cornification following pairing or at the expected end of pseudopregnancy for the experimental parabiont; however, in a few cases repeated vaginal smears were followed. At autopsy ovaries were fixed in Bouin's fluid for histological study. Sections were cut at 8 µ and stained with Mallory's triple stain. The presence of India ink verified the age of the corpus * Present address :

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“…In rats with hypophysial autografts, persistent corpora lutea regress after prolonged administration of either oxytocin or vasopressin (Faulkner & Hansel, 1962). In hysterectomized pseudopregnant rats, vasopressin decreases the duration of vaginal diestrous and hastens ovulation, apparently by causing luteal regression (Malven & Hansel, 1965) (Fig. 10).…”

Section: Role Of Neurohypophysial Hormones In the Uterus-pituitary-mentioning

confidence: 99%