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A selective increase in circulating inhibin and inhibin pro-alphaC at the time of ovulation in the mare.

The relationship between a selective increase in circulating immunoreactive (ir)-inhibin and the time of ovulation was investigated in mares. Concentrations of plasma ir-inhibin were measured every 4 h during the periovulatory period. Inhibin pro-alphaC, a precursor protein of the inhibin alpha-subunit, was also measured. The changes in ir-inhibin and inhibin pro-alphaC in circulation were parallel. Concentrations of both ir-inhibin and inhibin pro-alphaC in the plasma increased at the same time when ovulatory follicles ruptured, and the peak levels of circulating ir-inhibin and inhibin pro-alphaC were maintained for 4-8 h. There was no selective increase in plasma concentrations of estradiol-17beta during the process of ovulation. These results suggest that the selective increase in ir-inhibin and inhibin pro-alphaC was caused by the absorption of follicular fluid after the rupture of ovulatory follicles. These results also suggest that the measuring of plasma concentrations of ir-inhibin or inhibin pro-alphaC in mares might be a useful method for detecting the time of ovulation.

Animals↗

A comparison of the female reproductive cycles of autumn-spawning and winter-spawning strains of rainbow trout (Salmo gairdneri Richardson).

Annual changes in the plasma concentration of testosterone, 17 beta-estradiol, 17 alpha-hydroxy-20 beta-dihydroprogesterone, vitellogenin, and gonadotrophin were monitored by radioimmunoassay in females of autumn- and winter-spawning strains of rainbow trout. The annual profile of steroids and of vitellogenin, and the relationships between these parameters, were similar in the two strains, except that most changes occurred 2 months later in the winter-spawning strain than they did in the autumn-spawning strain. The times during which most fish ovulated in each strain were approximately 3 months apart, while gonadotrophin peaks, which were only detected about the time of ovulation, were 4 months apart. This phase shifting between the strains is discussed in terms of the environmental control of the reproductive cycle.

Animals↗

Distribution of spermatozoa in the female reproductive tract of the domestic cat in relation to ovulation induced by natural mating.

The purposes of this study were to demonstrate the localization of spermatozoa in the reproductive tract of female domestic cats before (30 min and 3 h after mating) and after ovulation (48 and 96 h after mating), and to evaluate the efficiency of two techniques for studying sperm distribution. Estrus was induced in twenty-four female cats using 100 IU eCG and the females were divided into four groups with six females per group. The same male cat was used for mating with all the females. One group of six females was mated once; the others were mated four times in 1 h. Ovariohysterectomy was performed at 30 min, 3 h, 48 h, and 96 h after mating and the excised reproductive tracts were divided into seven segments on each side: infundibulum, ampulla, isthmus, uterotubal junction (UTJ), cranial and caudal uterine horn, and uterine body. The vagina and the lumina of the segments from one side were flushed with 0.5 ml PBS. The flushed and the non-flushed segments from the contralateral side were then fixed in 3% neutral buffered formalin and processed for routine histology. The numbers of spermatozoa in the flushings and in 40 histological sections from each segment were counted. Before ovulation, the majority of spermatozoa was detected in the vagina and the uterine segments, whereas after ovulation, significantly higher numbers of spermatozoa were present in the uterine tubal segments. The decreasing gradient in sperm numbers at 30 min and 3 h after mating between the vagina, the uterine segments, including the UTJ, and the uterine tubal segments indicated that the cervix and the UTJ served as barriers for sperm transport in the cat. The UTJ and the uterine crypts acted as sperm reservoirs before ovulation whereas the isthmus was a sperm reservoir around the time of ovulation. There was no difference in sperm numbers in the tissue sections between flushed and non-flushed segments, implying that the flushing technique only recovered some intraluminal spermatozoa while most of the spermatozoa remained in the epithelial crypts. This was further supported by the finding that significantly higher numbers of spermatozoa were recovered in the flushings at 30 min and 3 h after mating, when more spermatozoa were free in the lumina, than at 48 and 96 h after mating, when the majority of the spermatozoa were entrapped in the uterine epithelial crypts.

Animals↗

[Prediction of ovulation].

Predicting ovulation is the basis on which the fertile period is determined. When we carried out observations on 60 spontaneous cycles it was possible to detect with precision the discharge of LH which would produce ovulation by taking series of plasma levels of LH. The start is defined as the time when the level of LH becomes 180% greater than the mean level observed in the previous 24 hours. Ovulation occurs between 37 and 39 hours after this threshold has been crossed. The discharge of LH is the most constant criterion and the most precise one, and it does make it possible to work out the chronology of the events that precede ovulation. Ultrasound and estimation of levels of oestradiol in the plasma or in the urine do allow one to appreciate how the follicle is maturing.

Body Temperature↗

[Rapid determination of plasma progesterone. Its value in ovarian stimulation for in vitro fertilization].

Plasma Progesterone levels show definite variations during the periovulatory period of the superovulated cycle similar to those of the physiological cycle. The question arises whether the pattern of these variations is of significance with regard to the success rate of the IVF cycle. This prospective study was conducted with a rapid and highly sensitive radioimmunoassay of plasma progesterone labelled with Iodine 125. A total of 452 cycles were initiated in 328 patients (280 cycles using a clomiphene citrate-HMG regimen, 272 cycles using an association of LHRH analogues with HMG according to three different protocols). Ovarian response was monitored with sonography and rapid plasma radioimmunoassays of 17 beta-estradiol, progesterone and LH (in non-analogue cycles). Plasma progesterone in particular was assayed 17 hours before, at the time, and 7 hours after the administration of HCG. 10,000 UI IM for triggering ovulation. During the Clomiphene-HMG therapy when LH levels are instable, the plasma progesterone assay is highly discriminant between the beginning of a true LH peak (with concomitant rise of progesterone greater than 1 ng/ml, 15.7% of the cycles) and hectic variations of LH (no concomitant rise of progesterone, 4.3% of the cycles); the progesterone assay was also able to detect the occurrence of ovulation in 3 cycles without sensible variation of plasma LH (1.1% of the cycles). Pre- and post-ovulatory levels of plasma progesterone also demonstrate a prognosis significance with regard to the chances of success of the cycle, with all the different types of ovarian stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Use of estradiol cypionate as a substitute for GnRH in protocols for synchronizing ovulation in dairy cattle.

Our purpose was to determine whether estradiol cypionate (ECP) could be substituted for the second GnRH injection of the standard Ovsynch protocol (injection of GnRH given 7 d before and 48 h after PGF(2alpha), with timed AI [TAI] 12 to 20 h after the second GnRH injection). Lactating dairy cows ranging from 61 to 82 d in milk at TAI were studied in 14 replicates. Main effects were hormone (ECP vs. GnRH) to induce ovulation and exposure to progesterone (P4) or not during the week preceding PGF(2alpha)-induced luteolysis. Four treatments were: 1) 100 microg of GnRH at 48 h after PGF(2alpha) (Ovsynch; n = 27); 2) same as Ovsynch, plus a P4-releasing intravaginal insert (CIDR) placed for 7 d beginning at the first GnRH injection (Ovsynch + CIDR, n = 20); 3) same as Ovsynch, but substituting 1 mg of ECP for GnRH, and injecting ECP at 24 h after PGF(2alpha) (Heatsynch; n = 33); or 4) Heatsynch + CIDR (n = 26). The largest follicle was identified by ultrasonography 24 h after PGF(2alpha) and was monitored every 6 h until ovulation. Incidence of estrus was less after GnRH (54%) than after ECP (87%), but more GnRH-treated cows had LH surges detected (95 vs. 65%) and ovulated (100 vs. 86%). Duration of LH surges, but not peak concentrations, was less after GnRH than after ECP (6.1 +/- 0.7 vs. 12.2 +/- 0.9 h). Pre-treatment with P4 reduced the incidence of LH surges but had no effects on incidence of estrus or ovulation. Intervals to the LH surge and ovulation were less after GnRH than after ECP, but intervals between onset of the LH surge and ovulation did not differ (26 +/- 2 vs. 30 +/- 3 h). We concluded that substituting ECP for GnRH resulted in more cows in estrus and slightly fewer ovulating.

Administration, Intravaginal↗

Plasma concentrations of immunoreactive (ir)-inhibin, gonadotropins and steroid hormones during the ovulatory cycle of the duck.

The present study was undertaken to determine changes in circulating levels of immunoreactive (ir)-inhibin, FSH, LH, estradiol-17beta, progesterone, and testosterone during the ovulatory cycle of Shao ducks. Serial blood samples were taken from two groups of laying ducks for measurement of ir-inhibin, gonadotropins, and steroid hormones at 2 h intervals for 24 h. Plasma concentrations of ir-inhibin did not change significantly during the ovulatory cycle. The highest level of plasma ir-inhibin was observed 6 h prior to ovulation, which coincided with a decreased level of plasma FSH. One FSH surge was found 12 h after ovulation. Estradiol-17beta, progesterone, and testosterone were also determined during the ovulatory cycle. Two peak values were detected for estradiol-17beta 8 h before ovulation and 4 h after ovulation, while progesterone started to increase 4 h before ovulation and reached a peak at ovulation. The highest level of plasma testosterone was detected around the time of ovulation. These results suggest that inhibin may be involved in the control of FSH secretion during the ovulatory cycle. In addition, both LH and progesterone are of importance in the ovulation process of Shao ducks.

Animals↗

[Use of a technic of bioluminescence for determining estrogens and LH during static and dynamic study of the ovary].

Estrogens and LH are necessary among other assays for ovulation diagnostic and ovarian monitoring during stimulations. They can be both measured with a method based on a bioluminescent reaction. This method measures, with a standard luminometer, the reduced NAD produced and accumulated by the reaction of two dehydrogenase enzymes: the estradiol dehydrogenase for direct assay of estrogens (estrone + estradiol), the glucose-6-phosphate dehydrogenase for gonadotrophin determination. These techniques can be applied to all biological fluids. They are simple and straightforward, do not need extraction and can be automated. Urinary assays are very useful in clinical practice to appreciate ovarian function, either during a spontaneous cycle or under stimulation, and are mandatory to decide the timing of hCG injection. The reported studies can be listed as follows: determination of preovulatory LH rise (LH greater than 10 Ul/g of creatinine) prior to embryo transfer after cryopreservation and thawing, detection of LH surges during ovarian stimulation, either premature surges causing premature luteinization, either normal surges when follicular maturation is adequate (296 cycles), confirmation of pituitary desensitization when using GnRH agonists (43 cycles), study of the initial stimulatory effect of GnRH agonists (13 patients). This effect can be responsible for the inadequate results obtained with the so-called "short protocol" in this experience when compared with the "long protocol" in the author's experience with compared with the "long protocol" (8 p. cent pregnancy rate per stimulation cycle versus 20 p. cent respectively, intrafollicular LH in 129 follicular fluids (86 with GnRH agonists and 43 without) has no correlation with the fecundability of the ovum. These results lead to extend bioluminescent techniques to the study of other parameters, and in particular FSH.

Buserelin↗

Cyclic changes in salivary lactate dehydrogenase, peroxidase and leucine aminopeptidase during menstrual cycle.

Salivary lactate dehydrogenase (LDH), peroxidase (Px) and leucine aminopeptidase (LAP) activities were scanned in both normally ovulating and anovulating women during entire menstrual cycle. In ovulating women, all the three enzymes exhibited significant increase in the activity on or before the onset of ovulation which was monitored by the shift of the basal body temperature (BBT) as well as the ferning pattern of the cervical mucus. The peak maximum at the midcycle was several times higher than the previous day value in all the six normal women. In anovulatory women, no such remarkable change in the enzyme activities was found throughout the cycle. Salivary LDH and LAP showed peak at the midcycle and at the same time required short time for assay, so the present results are strongly suggestive that the determination of salivary enzyme content may be a convenient method for detecting the day of ovulation.

Female↗

In situ morphologic dynamics of ovaries, uterus, and cervix in llamas.

The morphologic appearance of the ovaries, uterus, and cervix of nonpregnant and pregnant (less than 50 days) llamas (n = 21) were monitored daily by transrectal ultrasonography, and uterine tone was monitored by transrectal digital palpation. Follicle size and the presence or absence of corpora lutea were recorded and related to changes in morphology of uterus and cervix. Emphasis was given to the dynamics of curling of uterine horns and changes in uterine tone. For statistical purposes, uterine and cervical characteristics were scored 1 to 4 (minimal to maximal). Data were placed into 1 of the following reproductive statuses: 1) follicular dominance, 2) luteal dominance, and 3) pregnancy. Follicles were characteristically arranged along the periphery of the ovary, and large follicles and the corpus luteum protruded distinctly from the ovarian surface. The preovulatory follicle grew at a mean rate of 0.7 mm/day and the average diameter on the day before ovulation was 10.6 +/- 0.9 mm. Ovulation (Day 0) was detected an average of 1.8 days after a single mating. The mature corpus luteum was 11-13 mm in diameter and was characteristically hypoechogenic with a white (echogenic) horizontal area in the center. Pregnancy was detected as early as 11 days post-mating and all (7/7) singleton embryonic vesicles were detected in the left uterine horn. Uterine and cervical echotexture was darker (p less than 0.01) during follicular dominance than during luteal dominance and pregnancy, indicating a decrease in tissue interfaces or an increase in intercellular fluid during follicular dominance. The cervical folds became echogenic and prominent during luteal dominance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

SHORT INTEGUMENTS1/SUSPENSOR1/CARPEL FACTORY, a Dicer homolog, is a maternal effect gene required for embryo development in Arabidopsis.

The importance of maternal cells in controlling early embryogenesis is well understood in animal development, yet in plants the precise role of maternal cells in embryogenesis is unclear. We demonstrated previously that maternal activity of the SIN1 (SHORT INTEGUMENTS1) gene of Arabidopsis is essential for embryo pattern formation and viability, and that its postembryonic activity is required for several processes in reproductive development, including flowering time control and ovule morphogenesis. Here, we report the cloning of SIN1, and demonstrate its identity to the CAF (CARPEL FACTORY) gene important for normal flower morphogenesis and to the SUS1 (SUSPENSOR1) gene essential for embryogenesis. SIN1/SUS1/CAF has sequence similarity to the Drosophila melanogaster gene Dicer, which encodes a multidomain ribonuclease specific for double-stranded RNA, first identified by its role in RNA silencing. The Dicer protein is essential for temporal control of development in animals, through the processing of small RNA hairpins that in turn inhibit the translation of target mRNAs. Structural modeling of the wild-type and sin1 mutant proteins indicates that the RNA helicase domain of SIN1/SUS1/CAF is important for function. The mRNA was detected in floral meristems, ovules, and early embryos, consistent with the mutant phenotypes. A 3.3-kb region 5' of the SIN1/SUS1/CAF gene shows asymmetric parent-of-origin activity in the embryo: It confers transcriptional activation of a reporter gene in early embryos only when transmitted through the maternal gamete. These results suggest that maternal SIN1/SUS1/CAF functions early in Arabidopsis development, presumably through posttranscriptional regulation of specific mRNA molecules.

5' Untranslated Regions↗

Postpartum ovarian activity in dairy cows: Correlation between behavioral estrus, pedometer measurements and ovulations.

The efficacy of pedometers as estrus detection aids was tested in a group of 47 Holstein cows during the postpartum period. Pedometers were strapped on the left front leg of each cow on the day of parturition and pedometer measurements were recorded twice daily for 60 days. The cows were also observed twice a day for behavioral signs of estrus. Daily blood samples were collected during Days 1-30, and thereafter once every two days from Days 30-60 after parturition for progesterone assay. Rectal palpations of the ovaries were carried out once every four days during the first month after parturition. Based on the progesterone profiles and rectal palpation findings, 91 ovulations were recorded in 42 cows and 5 cows remained acyclic during the observation period. Seventy-six percent (69 91 ) of the ovulations were associated with pedometer indications of estrus, while only 35% (32 91 ) of the ovulations were associated with observed estrus. Fifty-seven percent (24 42 ) of the first postpartum ovulations were associated with pedometer measurements, but only 19% (8 42 ) of the first postpartum ovulations were associated with behavioral signs of estrus. Similarly, pedometers were superior to observations as a method of detection of estrus associated with the second and third postpartum ovulations (91% vs 37%, 92% vs 78% respectively). It is concluded that pedometers are useful aids for estrus detection, particularly in the immediate postpartum.

Journal Article↗

Interrelationship of plasma and urinary luteinizing hormone preovulatory surge.

The only reliable method of predicting spontaneous ovulation relies on the detection of the preovulatory luteinizing hormone (LH) surge in urine or plasma. The efficiency of the detection by means of plasma LH radioimmunoassay, urine LH radioimmunoassay or urine LH agglutination inhibition immunoassay were compared in 33 patients. The detection of the onset of LH surge was simultaneous in plasma and urine in only 11 cases. In two thirds of the patients, the urine LH surge onset is delayed by 3 to 21 h as compared with plasma LH surge onset. In some of these cases the oocyte would probably be missed if the laparoscopy had been scheduled according to urine data.

Adult↗

The effect of eCG or estradiol at or after norgestomet removal on follicular dynamics, estrus and ovulation in early post-partum beef cows nursing calves.

In post-partum anestrous beef cows suckling calves, neither the choice of hormonal regime to ensure the presence of a healthy dominant follicle at the end of a progestagen treatment nor the optimum hormone to induce estrus and ovulation is clear. Twenty-eight beef cows, in good body condition, 25-30 days post-partum, were assigned to one of four treatments: (i) 3mg norgestomet (N) implant with 5mg estradiol valerate (EDV) and 3mg N injection at the time of insertion (Crestar) for 5 days followed by 600 IU eCG at the time of implant removal; (ii) Crestar for 5 days as in (i) followed by 0.75 mg estradiol benzoate (EDB) 24h later; (iii) Crestar for 9 days followed by 600 IU eCG at the time of implant removal; and (iv) Crestar for 9 days followed by 0.75 mg EDB 24h later. Ovarian scanning was preformed from 4 days before implant insertion until ovulation and 4 days postovulation to detect the CL. Daily blood samples were collected from day 20 post-partum until second ovulation for FSH and E(2) assay. Data were analyzed using analysis of variance. There was no effect of the stage of follicle wave at the time of implant insertion on interval to new follicle wave emergence (range 1-7 days; mean 4.7 days). FSH concentrations were decreased to 5.9+/-2.0 and 7.7+/-1.1 ng/ml for pre- and post-selection cows 1 day after start of treatment; thereafter, they increased on Day 2 to 7.9+/-2.0 and 11.0+/-1.1 ng/ml and on Day 3 to 10.3+/-2.7 and 11.4+/-1.7 ng/ml for pre- and post-selection cows, respectively, despite high-estradiol concentrations at that time. There was no effect of treatment on the interval from implant removal to ovulation (3.2-4.0 days) or on the number of cows detected in estrus (26 of 27 cows). The size of the ovulatory follicle in cows given 0.75 mg EDB 24h post implant removal was decreased in animals at the pre-selection stage (12.2+/-0.1mm) of the follicle wave compared with those at the post-selection stage (15.3+/-0.9 mm) at implant removal. Cows given 600 IU eCG at the pre-selection phase of follicular growth had multiple ovulations (4.0+/-1.1). Cows given EDV at the start of a 5-day implant period had higher estradiol concentrations before and on the day of implant removal than those given EDV at the start of a 9-day implant period. The injection of 0.75 mg EDB 1 day after implant removal tended to increase concentrations of estradiol one day later. In conclusion, 5mg EDV and 3mg N at insertion of a 3mg N implant resulted in variable new follicle wave emergence 1-7 days later in post-partum beef cows nursing calves (22 of 27); both eCG and EDB were equally effective at inducing estrus after implant removal in cows in good BCS, but eCG resulted in a significant increase in ovulation rate in cows treated before dominant follicle selection.

Animals↗

Comparison of the effect of ovulation-inducing factor (OIF) in the seminal plasma of llamas, alpacas, and bulls.

We have recently reported the presence of an ovulation-inducing factor (OIF) in the seminal plasma of llamas and alpacas-species characterized as induced ovulators. The study was designed to test the hypothesis that the seminal plasma of bulls will induce ovulation in llamas, and to compare the ovulation-inducing effect of seminal plasma of conspecific versus hetero-specific males. The seminal plasma of alpacas, a closely related induced ovulator (Lama pacos), and cattle, a distantly related ruminant species (Bos taurus) considered to be spontaneous ovulators, were compared with that of the llama (Lama glama). Ovulation and maximum corpus luteum diameter were compared by ultrasonography among female llamas (n=19 per group) treated intramuscularly with 2 mL of phosphate buffered saline (PBS, negative control) and those treated with 2 mL of seminal plasma of bulls, alpacas, or llamas (conspecific control). The diameter of the preovulatory follicle did not differ among groups at the time of treatment. Bull seminal plasma induced ovulations in 26% (5/19) of llamas compared to 0% (0/19) in PBS group (P<0.001). The proportion of females that ovulated was lower (P<0.01) in bull seminal plasma group compared to the groups treated with alpaca or llama seminal plasma (100%). A corpus luteum was detected on Day 8 (Day 0=treatment) in all llamas in which ovulation was detected earlier (Day 2) by ultrasonography. The diameter of the CL did not differ among groups. Results document the presence of an ovulation-inducing factor in the seminal plasma of B. taurus. The interspecies effects of seminal plasma on ovulation and luteal development provide rationale for the hypothesis that OIF is conserved among both spontaneous and induced ovulating species.

Animals↗

Incidence of delayed ovulation in Holstein heifers and its effects on fertility and early luteal function.

In the first of 3 experiments 134 first-service and 108 repeat-breeder Holstein heifers were palpated at 12-hour intervals starting 24 hours after insemination to compare the incidence of delayed ovulation in the 2 groups. Delayed ovulation was defined as failure to ovulate within the first 24 hours after insemination. Ovulation occurred within 24 hours post insemination in 92.1% of the animals and was delayed in 7.9% of the cases, with no differences between first-service and repeat-breeder heifers, indicating that the subfertility of the repeat-breeder animals was not due to delayed ovulation. The duration of the delay was at most 12 hours since all the animals had ovulated by 36 hours post insemination. Conception rate of the 19 animals with delayed ovulation (42.1%) was not different (P>0.05) from that of the 223 heifers that ovulated on time (44.8%). In a second experiment, no differences were detected between 15 heifers with delayed ovulation and 15 animals that ovulated on time with respect to their progesterone concentrations during the first 8 days post insemination, indicating that delayed ovulation is not associated with delayed luteinization or subnormal early luteal function. In the third experiment, the conception rate of 126 repeat-breeder heifers that were treated with hCG at the time of insemination was 26.7%; the conception rate of 101 repeat-breeder heifers that were inseminated twice, at 12 and 24 hours after the onset of estrus, was 34.6%; and the conception rate of 105 repeat-breeder heifers which were not treated with hCG and which were inseminated only once was 30.5% (P>0.05) It is concluded that delayed ovulation is not an important cause of infertility and does not constitute an important component of the repeat-breeding syndrome in Holstein heifers.

Journal Article↗

Plasma endotoxin and concentrations of stable metabolites of prostacyclin, thromboxane A2, and prostaglandin E2 in postpartum dairy cows.

The presence of endotoxin in plasma and patterns of stable metabolites of prostacyclin (PC), thromboxane A2 (TXA2) and prostaglandin E2 (PGE2) were determined during the first postpartum estrous cycles in sixteen dairy cows. These included 8 cows with uterine infections which exhibited shortened luteal phases (SC) and 8 cows which had normal luteal phases (NC) after the first post partum ovulations. Endotoxin was consistently detected in all SC cows during the abbreviated estrous cycles while plasma samples of NC cows were free of endotoxin. Plasma concentrations of TXA2 metabolite was higher in SC cows (p less than 0.05) (1785-3452 pg/ml) compared to NC cows (723-1240 pg/ml). Similarly, plasma concentrations of PC metabolite was higher in SC cows (p less than 0.07) (423-1847 pg/ml) compared to NC cows (159-325 pg/ml). In contrast, plasma concentrations of PGE2 metabolite was higher in NC cows (p less than 0.05) (850-2219 pg/ml) compared to SC cows (455-628 pg/ml). The results of this study suggest that postpartum uterine infections mediate the release of prostaglandins from the uteri by means of the endotoxin and endotoxin appears to stimulate selectively the production of PC and TXA2 favoring early demise of corpora lutea formed after first postpartum ovulations in dairy cows.

Animals↗

Quantification of fecal estradiol and progesterone metabolites in Syrian hamsters (Mesocricetus auratus).

Alternative methods to the utilization of laboratory animal blood and its by-products are particularly attractive, especially regarding hamsters due to their small size and difficulties in obtaining serial blood samples. Steroid hormone metabolite quantification in feces, widely used in studies of free-ranging or intractable animals, is a non-invasive, non-stressor, economical, and animal saving technique which allows longitudinal studies by permitting frequent sampling of the same individual. The present study was undertaken to determine the suitability of this method for laboratory animals. Estradiol and progesterone metabolites were quantified by radioimmunoassay in feces of intact, sexually mature female Syrian hamsters during the estrous cycle (control) and in feces of superovulated females. Metabolites were extracted by fecal dilution in ethanol and quantified by solid phase radioimmunoassay. Median estrogen and progesterone concentrations were 9.703 and 180.74 ng/g feces in the control group, respectively. Peaks of estrogen (22.44 +/- 4.54 ng/g feces) and progesterone (655.95 +/- 129.93 ng/g feces) mean fecal concentrations respectively occurred 12 h before and immediately after ovulation, which is easily detected in this species by observation of a characteristic vaginal postovulatory discharge. Median estrogen and progesterone concentrations (28.159 and 586.57 ng/g feces, respectively) were significantly higher in superovulated animal feces (P < 0.0001). The present study demonstrated that it is possible to monitor ovarian activity in Syrian hamsters non-invasively by measuring fecal estradiol and progesterone metabolites. This technique appears to be a quite encouraging method for the development of new endocrinologic studies on laboratory animals.

Animals↗