Timing of Post-partum Ovulation in the Rat1

Hoffmann, Joan C.; Schwartz, Neena B.

doi:10.1210/endo-76-4-620

Cited by 45 publications

(33 citation statements)

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“…The tendency for the T/S ratio to be higher following progesterone delayed ovulation may be related to the fact that the 'critical period' of LRF release is more prolonged than normal when ovulation has been delayed (Everett, 1951;Hoffman & Schwartz, 1965b). Similarly, a prolonged period of LRF release appears to occur on the evening preceding post-partum ovulation in the rat (Hoffman & Schwartz, 1965a) (Hoffman & Schwartz, 1965b) which may account for the moderate rise in T/S ratio despite a prolonged period of LRF release. Towards the end of pseudo-pregnancy it is also high but there is a suggestion that an abrupt fall in LH content may occur the day before ovulation under these conditions (Schwartz & Rothchild, 1964).…”

Section: Discussionmentioning

confidence: 99%

The effects of a single injection of progesterone on the oestrous cycle, thyroid gland activity and uterus‐plasma concentration ratio for radio‐iodide in the rat

Brown-Grant¹

1967

The Journal of Physiology

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SUMMARY1. A single subcutaneous injection of 5 mg, 1-25 mg or 625 ,tg, but not 312 jtg, of progesterone in oil delayed ovulation in the rat by 1 or more days, when injected at the dioestrous stage of a 4-day oestrous cycle.2. When ovulation was delayed in this way the expected increase in the thyroid-serum concentration ratio for 1311 was also delayed but the ratio did increase when delayed ovulation occurred.3. A single injection of progesterone resulted in an increase in the uterusplasma and oviduct-plasma concentration ratios for 1311; the increase was greatest when steroid was injected at the dioestrous stage of the cycle and was delayed and least when the steroid was given at the pro-oestrous stage. 4. Ovulation was advanced by 1 day when progesterone was injected on the second day of dioestrus in rats showing regular 5-day cycles; this ovulation was not accompanied by an increase in the thyroid-serum concentration ratio. In these experiments a dose of progesterone that failed to advance ovulation produced a rise in uterus-plasma and oviductplasma ratio for 1311 but no rise was seen when ovulation was induced, suggesting that oestrogen secretion had been stimulated. 5. 20a-Dihydroprogesterone (pregn-4-en-20ax-ol-3-one) was not effective in delaying or advancing ovulation at a dose level of 2-5 mg per rat and had no effect on the uterus-plasma concentration ratio for radio-iodide.6. These results are discussed in relation to the hypothesis that the increase in thyroid gland activity at the oestrous stage of the cycle is related to the neuro-endocrine changes that lead to ovulation.

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Section: Discussionmentioning

confidence: 99%

The effects of a single injection of progesterone on the oestrous cycle, thyroid gland activity and uterus‐plasma concentration ratio for radio‐iodide in the rat

Brown-Grant¹

1967

The Journal of Physiology

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“…The advantage of a mesh floor is that it enables the copulatory plugs to be easily recovered. The dam and the pups are reunited in their own cages the following morning at 0800 h. A certain number of rats, especially those which litter during the late afternoon or evening, do not ovulate during the first night post partum (Hoffman & Schwartz, 1965). These animals have negative vaginal smears the following morning.…”

Section: Recommended Technique For Post-par Tum Matingmentioning

confidence: 99%

“…Rats ovulate during the 1st or 2nd night following parturition (Hoffman & Schwartz, 1965). Subsequently, oestrus is not usually observed during lactation.…”

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confidence: 99%

Effect of removing pups when mating lactating rats at the post-partum oestrus

Kali

Amir

Morag³

1971

Lab Anim

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“…Female albino rats usually ovulate during the dark period following parturi¬ tion (Hoffmann & Schwartz, 1965;Johnson, 1972). The relationship of par¬ turition to ovulation is of interest since it has been shown that the time of day of parturition has an important influence on the subsequent timing of gonadotrophin release and ovulation (Johnson, 1972).…”

Section: Introductionmentioning

confidence: 99%