Anovulatory Period Research Articles

Acute effect of suckling on gonadotropin, prolactin and glucocorticoid concentrations in serum of intact and ovariectomized beef cows

Suckling may prolong the anovulatory period postpartum by 1) a neural-mediated inhibition of luteinizing hormone-releasing hormone (LHRH)-induced gonadotropin secretion, or 2) an inhibitory effect of hormones released by suckling on gonadotropin secretion and/or action at the ovary. In the present investigation we considered whether a suckling event caused 1) acute inhibition of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion, and 2) release of glucocorticoids and/or prolactin (PRL). Six Hereford cows remained intact and six were ovariectomized (ovx) on day 7 postpartum. Calves remained with their dams continuously. Cows were bled at 10-min intervals during 6 consecutive hr on days 14, 28 and 42 postpartum. Both LH and FSH were released episodically by day 14 in intact and ovx cows, but suckling did not acutely affect LH and FSH secretion. A PRL release accompanied suckling 67, 96 and 95% of the time. However, among all instances where PRL was released on days 14, 28 and 42 postpartum, 67, 29 and 37% occurred independent of a suckling event. Glucocorticoids were not released by suckling in intact cows but were released in ovx cows. We conclude that suckling does not acutely affect LH or FSH concentrations in serum of cows postpartum, that PRL concentrations usually increase in serum coincident with suckling but can be released at other times, and suckling-induced glucocorticoid release depends upon the presence of the ovary.

Control of ovulation in farm animals.

Examination of hormonal changes occurring in farm species at the onset of puberty, during the follicular phase of the oestrous cycle, and at those times when ovarian activity is re-established after periods of seasonal or lactational anoestrus, provides circumstantial evidence that the final phases of follicular development are dependent on a pattern of tonic (episodic) LH secretion. A suppression of episodic LH secretion is associated with periods of anovulation. Stimulation of tonic LH secretion by repeated injections of small doses of synthetic Gn-RH or purified LH restores normal reproductive function in all but deeply anoestrous animals. Continuous infusion of Gn-RH is as effective as repeated injections. It is suggested that an additional inadequacy, possibly endocrine, contributes to the anovulatory state in deep anoestrus.

Influence of pre- and post-partum nutrition on LH secretion in suckled postpartum beef heifers

The influence of nutrition during the last trimester of pregnancy and the early postpartum period on postpartum LH secretion was evaluated in two-year-old Hereford and Simmental heifers maintained on a high or low plane of nutrition (experiment 1) or in Hereford heifers fed a high or low energy (150% vs 100% NRC) ration (experiment 2). Amount of LH released with 10 mg estradiol benzoate (IM) at 14 and 28 days postpartum in experiment 1 or at 14,32,50 and 74 days postpartum in experiment 2 was less (P<.01) for heifers fed the low vs high plane or energy ration and less (P<.05) at 14 days postpartum than at subsequent postpartum periods. The interval from estradiol benzoate injection to the LH peak concentration was longer (P<.05) in Simmental than Hereford heifers, longer (P<.05) in heifers fed the low rather than high energy ration, and longer (P<.01) at 14 days postpartum than at subsequent postpartum periods. The amount of LH released was inversely related to the time required for initiation of the release (r = −.62). Tonic LH secretion was higher (P<.05) in heifers fed the high energy ration and was correlated with average daily gain (r = .75), but was unaffected (P.05) by days postapartum or breed of cattle. Results indicate that increased dietary energy intake increases LH secretion and shortens the anovulatory period in suckled postpartum beef heifers.

Natural Family Planning

Departamento de Obstetncia. Ginecologia y Pennatologia. Universidad Catolica de Chile, Santiago, Chile

Effects of ingested petroleum on plasma levels of ovarian steroid hormones in photostimulated mallard ducks.

Ovarian maturation was slowed significantly when photostimulated mallard ducks were given petroleum-contaminated food. When they started to lay, oviposition occurred in erratic short sequences interrupted by long anovulatory periods, and eggs were laid during a longer-than-normal interval of the daily light phase. During the ovulatory cycle, mean daily plasma concentrations of estradiol and estrone were significantly lower in contaminated than in uncontaminated birds. Preovulatory variations in plasma estrogen concentration in uncontaminated birds consisted of two maxima separated by a well-defined nadir during mid-phase; no significant cyclical changes occurred in the contaminated birds. Consumption of contaminated food did not affect mean daily plasma progesterone concentrations during the ovulatory cycle. In both groups, preovulatory variations in plasma progesterone consisted of a single peak during the 9-hr period preceding ovulation. During short pauses in egg-laying, mean daily estradiol and estrone concentrations declined significantly in the uncontaminated but not in the contaminated birds. During longer pauses, which occurred only among contaminated birds, plasma concentrations of estradiol and progesterone were both significantly lower than they were during short pauses.

Modulation of functional capacity of small ovarian follicles in the post-partum cow by prolactin.

This study was undertaken to examine the possibility that the prolonged anovulatory period frequently experienced by the post-partum cow is due to a disruption of function at the ovarian level promoted by the high, suckling-induced, blood prolactin concentrations. Fifteen cows, less than 35 days post partum, were allocated to three groups (1, 3 and 5) and given no hormonal treatment, prostaglandin plus pregnant mare serum gonadotrophin (PMSG) treatment or injected with 2-bromo-alpha-ergocryptine to reduce circulating prolactin levels. Ten synchronized cyclic cows were allocated to two groups (2 and 4) and given prostaglandin or prostaglandin plus PMGS treatment. All cows were ovariectomized 1 or 2 days after treatment of Graafian follicles less than 9 mm in diameter were selected after dissection from the ovaries. The follicles were cultured for 18 h with or without prolactin (1 microgram/ml) and steroid accumulation in the culture medium estimated. The follicles were then separated into theca and granulosa which were incubated for 40 min with LH (1 microgram/ml) or FSH (5 micrograms/ml). Cyclic AMP concentrations were estimated as an indication of tissue responsiveness to gonadotrophins. The secretion of oestradiol-17 beta, progesterone, testosterone or androstenedione during 18 h culture did not differ between follicles isolated from post-partum or cyclic cows. The presence of prolactin in the culture medium had no overall effect on steroid secretion although some specific effects within each group were noticed. Incubation with LH increased cyclic AMP levels in the theca but the granulosa did not respond. Likewise FSH increased cyclic AMP levels in granulosa preparations but not in theca. There were no differences in response between post-partum and cyclic cows, but exposure of the follicles to prolactin in vitro did significantly reduce the LH-induced increase in cyclic AMP levels in isolated theca. We have concluded that endogenous prolactin may modify but does not inhibit the resumption of ovarian function following parturition in the beef cow.

Some observations concerning the role of progesterone in the control of ovulation.

Pre-ovulatory LH-surges in 4-day cyclic rats (4d-r) were postponed 1,4, or 8 days by treatment with progesterone (P), or 1 day by treatment with pentobarbitone just prior to the onset of the 'critical period' on pro-oestrus. P-delayed LH-surges tend to become higher with increasing duration of the preceding anovulatory period: 1 day-delayed surges were as high as 5d-r surges (i.e. about twice as high as spontaneous 4d-r surges); 8 days-delayed surges were significantly higher. Compared with 4d-r surges the time of onset and zenith of P-delayed surges is significantly advanced. The 1 day-pentobarbitone-delayed surges too were as high as 5d-r surges, but still timed as 4d-r surges. On no 'artificial' pro-oestrus day did the responsiveness of the pituitary differ from the 'normal' pro-oestrus responsiveness. It is concluded that P influences the timing but not the height of pre-ovulatory LH-surges.

"INCESSANT OVULATION" AND OVARIAN CANCER

A case-control study of 150 ovarian cancer patients under the age of 50 and individually matched controls was done to study the influence of fertility and oral contraceptive use on the risk of ovarian cancer. The risk decreased with increasing numbers of live births, with increasing numbers of incomplete pregnancies, and with the use of oral contraceptives. These three factors can be amalgamated into a single index of protection—"protected time"—by considering them all as periods of anovulation. The complement of protected time—viz., "ovulatory age", the period between menarche and diagnosis of ovarian cancer (or cessation of menses) minus "protected time"—was strongly related to risk of ovarian cancer. Other factors found to be associated with increased ovarian cancer risk were obesity, cervical polyps, and gallbladder disease. Women who had an "immediate" intolerance to oral contraceptive use had a fourfold increased risk of ovarian cancer. 7 patients, but no controls, could recall a family history of ovarian cancer.

Pharmacokinetic and pharmacodynamic effects of small doses of norethisterone released from vaginal rings continuously during 90 days

The pharmacokinetic and pharmacodynamic effects of norethisterone (NET) released continuously from vaginal devices at a rate of 50 μ g 24 h and 200 μ g 24 h , respectively, were investigated during a 90-day period in two groups of 7 women each with regular menstrual periods. Blood samples were taken three times weekly (Mondays, Wednesdays and Fridays) during a control cycle and during the entire study period for the estimation of estradiol, progesterone and NET levels, and hourly blood samples were collected throughout a 24-hour period after 6 weeks of exposure to assess the short-term variation in NET levels. In addition, an endometrial biopsy was taken on days 21–23 of the control cycle and after 6 and 10 weeks with the device in situ . There was little, if any, initial “burst” effect on the plasma levels of NET following the insertion of the devices, and a statistically significant linear relationship was found in each case when the NET levels were plotted against the 90 days of exposure. However, the average slope of the regression lines with the 50 μg-releasing devices (−0.44) was significantly flatter than that with the 200 μg-releasing devices (−1.63). Also the mean plasma level in the former group (283 pg/ml) was significantly lower than that (666 pg/ml) observed in the latter group. The average daily decline in plasma NET levels was 0.16% and 0.24%, respectively, and the 95% confidence limits of the hour-to-hour variation in NET levels were at 92 and 106%. All control cycles were of normal length (26–35 days) and exhibited a normal luteal activity. There were a total of 16 cycles with normal luteal function among the 7 subjects with 50 μg-releasing devices; each of them had a minimum of 2 such cycles. However, 11 of these 16 cycles were of abnormal length, indicating a significant effect of norethisterone on the follicular phase. Only 9 cycles were found with a normal luteal activity in the group with the devices releasing 200 μ g 24 h ; 3 of the subjects in this group had anovulation throughout the entire study, and 2 of them had prolonged anovulatory periods alternating with normal cycles. Thirteen of the 14 biopsies taken with the 50 μg-releasing devices in situ after 6 and 10 weeks of exposure showed normal cyclic changes, whereas 11 of the 14 biopsies taken in the group exposed to a release rate of 200 μ g 24 h indicated predecidual and atrophic changes. These were associated with a significantly diminished number of endometrial glands per microscopic field and with a significant increase in the number of days with bleeding and spotting. Hence, the increased frequency of intermenstrual bleeding may be associated with the predecidual and atrophie changes induced by the administration of NET. No correlation was found between the individual plasma levels of NET and the following parameters: weight, height and ponderal index of the subjects, individual release rate of NET from the devices, effects on ovarian function, the appearance of the endometrium and the number of days with bleeding and spotting. It is concluded that the vaginal rings studied provide a near zero order release of norethisterone and represent an ideal experimental model for the study of the effects of constant blood levels of contraceptive steroids.

Pituitary-Ovarian Relationships in Polycystic Ovary Syndrome

The spontaneous pattern of pituitary gonadotropins and ovarian steroids and their response to dynamic tests were measured in 12 women with polycystic ovarian syndrome (PCO) and the results compared to those from 6 normal women during the early follicllar phase of the cycle (controls). As judged by serial measurements of urinary total estrogen and pregnanediol over a 12-week period, in PCO patients 75% of cycles were anovulatory (anovulatory PCO) as compared to 100% ovulatory in controls. The basal concentrations of LH, androstenedione and estrone were significantly higher and the concentration os FSH significantly lower in anovulatory PCO than in the controls (P less than .05). In PCO patients the concentration of LH was lower following an ovulatory cycle than that following a period of anovulation. Negative and positive feedback responses to an estrogen provocation test (200 microgram ethinyl estradiol per day for 3 days) were normal in anovulatory PCO although the LH peak occurred 24 h earlier than in the controls. The amplitude of the pulses of LH was significantly greater in anovulatory PCO than in the controls and was suppressed in both groups after ethinyl estradiol. The peak release of LH in response to 56 microgram LRF in ovulatory PCO was similar in controls but LH responses in anovulatory PCO were significantly greater. It is suggested that the abnormalities in gonadotropin secretion in PCO are secondary to excessive and prolonged extraglandular production of estrogen from androstenedione.

Prolonged Breastfeeding as a Birth Spacing Method

Studies of European populations rural Punjab India and Taiwan have shown that women who nursed for 1-2 years and did not practice contraception had birth intervals 5-10 months longer than those who did not nurse. Lactation has a fertility reducing effect that lasts a little less than a year. Conception rates are also reduced during a period of lactation amenorrhea. Comparisons with newly married women show that after the onset of menstruation fecundity is reduced as a consequence of nursing. The duration of lactation was directly related to the length of the anovulatory period. Partial breastfeeding is not as effective in delaying ovulation as full breastfeeding. Where family planning services are available there should be no reliance on lactation as a birth spacing method.

The effect of lactation on the length of the post partum anovulatory period: An application of a bivariate stochastic model

A model of the effects of lactation on the post partum anovulatory period is presented. Parameters are estimated and the model is seen to fit the data of Perez et al. (1971) very well. Models of this type can be used to study other situations in which individuals change randomly over time in characteristics which affect a dependent behavioral process. It is hypothesized that the relative effects of nursing on post partum sterility are constant across societies, although the absolute effects vary from society to society. The hypothesis is shown to be in agreement with a variety of apparently inconsistent studies in the literature.

Effect of breast-feeding on postpartum menstruation, ovulation, and pregnancy in Alaskan Eskimos

Use of life-table analysis for measurement of the conception rate among Alaskan Eskimos substantiates the findings previously reported that two factors serve to differentiate nursing from nonnursing women in relation to conception post partum. The first is the anovulatory period of postpartum amenorrhea which is found to be longer for nursing women than for nonnursing women. The second is that the number of anovulatory cycles after menstruation recurs is greater for nursing women than for nonnursing women. Both of these factors, being additive, result in a longer interval between pregnancies for nursing women than for nonnursing women where contraceptive methods are not used. The consistency of the findings for the Alaskan Eskimos with those reported for women in India show that the physiologic effect of nursing on the rate of conception is independent of climate.

Ovulation inhibition with a long-acting injectable contraceptive: IV. Return of reproductive function after discontinuation

Thirty-one patients who completed 24 monthly injections with a long-acting injectable estrogen-progestogen contraceptive were followed with basal body temperature and regular urinary pregnanediol determinations until return of ovulatory function was established. Selected patients were studied for plasma gonadotropin patterns and for pituitary reserve by Metopirone tests. Sixteen patients who had received 24 consecutive montly injections required from 12 to 42 weeks to establish spontaneous ovulation. Three patients who received clomiphene citrate after 20 weeks of anovulation promptly ovulated and subsequently maintained regular ovulation. Six patients who discontinued the injections prior to 2 years demonstrated a correlation between the number of injections and the length of posttreatment anovulation. Six patients who received their injections bimonthly during the last 6 months of treatment returned to ovulatory cycles within 8 to 16 weeks. These patients had unacceptable irregularity of their withdrawal flow while taking injections bimonthly. Serial determinations of FSH and LH by radioimmunoassay on selected patients showed depression of FSH and lack of an LH peak during the period of anovulation, but normal patterns once ovulation recurred. All patients studied showed normal response to Metopirone tests after discontinuation of the drug. All patients ultimately returned to normal ovulatory cycles.

Births averted by contraception: An approach through renewal theory

Of critical interest to family planning administrators are estimates of births averted per segment of contraception. By a “segment” of contraception is meant the period of usage of a method between its initiation (or resumption after a period of nonuse) and its next interruption owing to accidental pregnancy, switch to another method, or stopping contraception. Several attempts to estimate births averted per IUD inserted have been pub1ished.l These analyses have been too tailored to specific data and too empirical to provide an ideal vehicle for clarifying the conditions under which births averted per segment of contraception is high or low. Nevertheless, these applied analyses have served to establish some of the factors that deserve place in a theory of family planning impact. Because they provide such efficient protection against pregnancy, modern contraceptives such as the IUD or the antiovular pills have an impact that is limited less by accidental pregnancy than by high discontinuation rates for other reasons. Another qualifying factor is the amount of overlap between practice of the contraceptive and the anovulatory period following childbirth when the woman is protected anyway. Even when all these factors are held

Reduction of Variability in the Anovulatory Period Following Medroxyprogesterone Acetate Injection by Using Jet Injectors

First 5 different types of jet injectors were tested in 4 mammalian species including man with medroxyprogesterone acetate (MPA). Penetration was generally good with the Dermo-jet Press-o-jet and Hypospray but inadequate with the Syrijet. Because the Dermo-jet allowed administration of a small volume it was employed in further rat studies. Larger aggregates of MPA consistently occurred in fascial planes and within muscle bundles when 5 mg of MPA were given by needle rather than Dermo-jet. In fact in animals needle-injected large deposits of crystals could still be found after animals resumed estrous cycles. Within 24 hours after administration by either needle or Dermo-jet leukocytic infiltration occurred around the microcrystal mass; a mononuclear inflammation occurred afterwards. When 2.5 mg or more of MPA were injected both the first and third cycles after the effects of the drug wore off occurred significantly sooner in the Dermo-jet rats (p less than .01). Women should be more receptive to the form of contraception represented by the Dermo-jet than to the needle injection since there is more certainty as to when menstruation should begin again with the use of the former method. The finer distribution of MPA crystals after Dermo-jet injection may hasten absorption.

NDT—‘Sound’ reasons for the use of ultrasonics

The Catalonian donkey breed is in danger of extinction, and much needs to be learned about the reproductive features of its females if breeding and conservation programmes are to be successful. This study reports the oestrous behaviour, oestrus cycle characteristics and dynamic ovarian events witnessed during 50 oestrous cycles (involving 106 ovulations) in 10 Catalonian jennies between March 2002 and January 2005. These jennies were teased, palpated transrectally and examined by ultrasound using a 5 MHz linear transducer—daily during oestrus and every other day during dioestrus. Predictors of ovulation were sought among the variables recorded.The most evident signs of oestrus were mouth clapping (the frequent vertical opening and closing of the mouth with ears depressed against the extended neck) and occasional urinating and winking of the vulval lips (homotypical behaviour). Interactions between jennies in oestrus were also recorded, including mounting, herding/chasing, the Flehmen response, and vocalization (heterotypical behaviour).Nine jennies ovulated regularly throughout the year; one had two anovulatory periods (54 and 35 days). The length of the oestrus cycle was 24.90 ± 0.26 days, with oestrus itself lasting 5.64 ± 0.20 days (mean ± S.E.M.) and dioestrus 19.83 ± 0.36 days. The incidence of single, double and triple ovulations was 55.66% (n = 59), 42.45% (n = 45) and 1.89% (n = 2), respectively. No significant difference was seen in the number of ovulations involving the left and right ovaries (52.63% [n = 70] compared to 47.37% [n = 63] respectively; P > 0.05). The mean interval between double ovulation was 1.44 ± 3.98 days. The mean diameter of the preovulatory follicle at day −1 was 44.9 ± 0.5 mm; the mean growth rate over the 5 days before ovulation was 3.7 mm/day.Data on preovulatory changes in oestrous behaviour, follicle size, follicle texture, the echographic appearance of the follicle and uterus, and uterine tone were subjected to stepwise logistic regression analysis to detect predictors of ovulation. The logit function showed the best predictors to be follicle size, follicular texture and oestrous behaviour. Certain combinations of these three variables allow the prediction of ovulation within 24 h with a probability of >75%.

Modification of the mentrual cycle in rhesus monkeys by reserpine.

8 rhesus monkeys were given reserpine 1 mg/kg (maximal tranquilizing dose) daily except Sundays 5 monkeys for 8-19 days and 3 monkeys for 100 days or more. Observations were made of cycle length ovulation by rectal palpation histology of ovary and uterus and vaginal lavage. Except for the first menstruation expected after the summer anovulatory period menstruation was delayed 47-140 days in the 3 monkeys given chronic reserpine. In 2 monkeys given reserpine from Cycle days 8-18 ovulation was normal but in 3 treated on Days 2-10 or 12 ovulation was delayed at least until Day 23. Cycle length was 15-39 days in 94% of the colony.

Presacral neurectomy

Presacral neurectomy is an often neglected method of alleviating dysmenorrhea which will give uniformly excellent results in selected cases. The selection of suitable cases can be removed from the realm of speculation as to the outcome by testing the patient beforehand by either intravenous sodium amytal or by producing an anovulatory period. Reports of fifteen patients completely relieved of all menstrual complaints by this type of surgery are included.