Serum concentrations of oestradiol and progesterone during the normal oestrous cycle and early pregnancy in the lion (Panthera leo)

During a 6-month study period weekly serum samples demonstrated 9 oestradiol surges above 14 pg/ml (range 19-108 pg/ml) among 3 lionesses isolated from male lions. Intervals between peaks ranged from 3 to 8 weeks. Progesterone surges of more than 17 ng/ml (range 17-282 ng/ml) and lasting for 2-6 weeks were recorded after 7 of the oestradiol peaks. Sexual behaviour correlated well with the oestradiol peaks. Except for cornification following oestradiol peaks, there was no obvious vaginal cytology pattern at other times of the cycle. Pregnancy occurred after a 12-h contact with a male during behavioural oestrus. During gestation (108 days) oestradiol values remained low, while progesterone was elevated to 49 ng/ml within 12 h after mating, reaching a peak of 143 ng/ml at the 4th week, and remaining elevated during the next 2 months.     

Control of oestrus in cattle using progesterone coils

Four experiments were conducted to determine the effect of length of treatment, stage of cycle at start of treatment and administration of oestradiol benzoate or progesterone at the start of treatment with intravaginal progesterone coils on oestrous response and fertility. In Experiment 1, the number of heifers in oestrus was affected neither by injection of 5 mg oestradiol benzoate alone or with 200 mg progesterone nor by length of treatment. More heifers (P < 0.05) were in oestrus on day 2 after treatment following a 12-day treatment compared to a 9-day treatment.In Experiment 2, heifers between days 17 and 20 of the oestrous cycle received an injection of either 5 mg oestradiol benzoate alone or with 200 mg progesterone at the start of a 9-day treatment with progesterone coils. Neither the number of heifers in oestrus nor the pattern of onset were affected after treatment. In Experiment 3, heifers between days 0 and 3 of the oestrus cycle received progesterone coils for 9, 12 or 14 days. In addition, animals received (i) no further treatment, (ii) a gelatin capsule adhered to the coil containing 10 mg oestradiol benzoate (iii) a gelatin capsule adhered to the coil containing 200 mg progesterone. Following a 9- or 12-day treatment period heifers receiving the coil with the oestrogen capsule had a high oestrous response ( compared to , P < 0.05). When oestrogen was not given, there was a significant linear effect of duration of treatment on the number in oestrus (9 days, ; 12 days ; 14 days, ; P < 0.05).In Experiment 4, post-partum cows were used to compare a 9- and 12-day treatment period and half the animals in each group received either 5 mg oestradiol benzoate and 200 mg progesterone at the start of treatment or a 10 mg gelatin capsule adhered to the coil. The length of treatment affected the number of heifers in oestrus since were in oestrus after a 12-day treatment period compared with after a 9-day period (P < 0.001). There were no significant differences in the number of cows in oestrus after injection of oestrogen and progesterone ( ) or after the use of the gelatin capsule ( ).     

Oestrous cycle of captive southern hairy-nosed wombats (Lasiorhinus latifrons) in South Australia, Australia

There is limited information available on the oestrous cycle of female southern hairy-nosed wombats (Lasiorhinus latifrons). This is mainly due to an extremely poor breeding success in captivity and the difficulty in routine recapturing of these cryptic, semi-fossorial animals in the wild. The aim of this study was to characterise the oestrous cycle of this species by monitoring peripheral plasma concentrations of progesterone and oestradiol, assessing changes in vaginal cytology, pouch condition and the urogenital sinus. Eight adult female wombats were monitored during the breeding season (July-December) over 2 years (2002-2003). Samples were collected up to three times a week. Vaginal smears contained several cell types, categorised by morphology, as either superficial epithelial cells or parabasal-intermediate cells. Leucocytes were also counted. Plasma progesterone profiles showed a mean oestrous cycle length of 36.33+/-0.67 days with a peak progesterone concentration of 139.53+/-10.62nmol/L. Levels of oestradiol peaked at a mean level of 467.33+/-44.32pmol/L on average 5 days before a rise in plasma progesterone values. The proportion of epithelial cells in vaginal smears varied throughout the cycle, with a high percentage of superficial epithelial cells observed during the follicular phase. During periods when progesterone concentrations were high, a greater percentage of parabasal-intermediate cells was observed. In conclusion, this study has characterised the oestrous cycle of the southern hairy-nosed wombat and confirmed that changes in vaginal smears together with pouch and urogenital sinus details could be used to determine signs of oestrus in this species.     

Follicular dynamics and temporal relationships among body temperature, oestrus, the surge of luteinizing hormone and ovulation in Holstein heifers treated with norgestomet

The effects of chronic treatment with norgestomet on follicular dynamics, corpus luteum growth and function as well as the temporal relationships among body temperature, oestrous behaviour, the luteinizing hormone (LH) surge and ovulation following implant removal were studied in 16 Holstein heifers. Oestrous cycles of the heifers were initially synchronized using 2 injections of prostaglandin F-2 alpha (PGF-2 alpha) 12 days apart. The heifers were then implanted with a norgestomet ear implant for 9 days, beginning either at the middle of the synchronized cycle (dioestrus) or at the end of the synchronized cycle (pro-oestrus). Follicular dynamics, corpus luteum growth and regression, and plasma progesterone were not affected by norgestomet treatment at dioestrus. The dominant follicle present at the time of norgestomet implantation in the pro-oestrus group was maintained during the 9-day implant period of 6 of 8 heifers and ovulated after implant removal. Time from implant removal to onset of standing oestrus and time to LH peak following implant removal were highly correlated with the time of ovulation (r = 0.92 and 0.96, respectively). Onset of standing oestrus and the LH peak and the onset of standing oestrus and peak vaginal and rectal temperatures were also highly correlated (r = 0.96, 0.82 and 0.81, respectively). It is concluded that any decrease in pregnancy rates following treatment with norgestomet is not due to asynchrony among oestrus, the LH surge and ovulation.     

Influence of time of mating and paced copulation on induction of pseudopregnancy in cyclic female rats

The present experiment was designed to examine whether changes occur during the course of behavioural oestrus in the sensitivity of the female to copulatory stimulation and in patterns of sexual behaviour which might influence the likelihood of luteal maintenance. Cyclic female rats were mated on the evening of pro-oestrus (21:00 h) or early on the morning of oestrus (05:00 h) and received either 5 or 10 intromissions from males under conditions which allowed or did not allow pacing of contacts with males to occur. During mating, the levels of sexual receptivity, the timing of sexual mounts from males, and pacing behaviours were measured. The occurrence of pseudopregnancy or pregnancy in each animal was determined by examining vaginal smears for 14 days after mating and by examining the uterus for the presence of fetuses at the end of the experiment. At both mating times, pacing of copulation with males increased the likelihood of prolonged luteal activity. However, females were more likely to become pseudopregnant following non-paced mating at 05:00 h than at 21:00 h the previous evening. Of those females receiving an ejaculation during mating, no difference were seen between groups in the incidence of pregnancy. This change in sensitivity to cervical-vaginal stimulation during oestrus was not associated with changes in sexual receptivity or pacing behaviour. The ability of cervical-vaginal stimulation to induce pseudopregnancy therefore increases toward the end of the period of oestrus, but the behavioural mechanisms which regulate receipt of such stimulation remain constant during that time.     

Effect of exogenous progesterone on 17 beta estradiol secretion in 4-day cyclic rats]

The rate of ovarian 17 beta oestradiol was showed to be decreased on the decreased on the afternoon of dioestrus 2 in 4-day cyclic female rats with cycles prolonged to 5 days following progesterone treatment as compared to untreated 4-day cyclic females. OEstradiol values also appeared lower on dioestrus 3 and prooestrus in experimental 5-day cycles than, on prooestrus, in natural 4-day cycles.     

Changes of electrical impedance in vaginal vestibule in cyclic sows

The changes of the electrical impedance in the vaginal vestibule during the oestrous cycle and the influence of sow parity on the vestibular impedance in oestrus were examined. Primiparous and multiparous sows of the Large White breed were used. Oestrus was tested via exposure of sows to a sexually mature boar. The criterion for conformation of ovulation was the increase in plasma progesterone levels above 12.5nmoll(-1) on day 8 and 12 after oestrus onset. A two-terminal method was used to measure the impedance. The vestibular impedance rose slightly in the first day after weaning. The impedance increased markedly during oestrus (P<0.01) and decreased during early dioestrus (P<0.01). No significant changes were observed thereafter. The individual sows reached the peak of vestibular impedance between 1 and 3 days after oestrus onset. The parity of sows did not significantly influence the impedance values during oestrus. The study showed that the impedance changes in the vaginal vestibule during peri-oestrus are considerably different from those described earlier in the vagina and that sow parity does not affect the vestibular impedance in oestrus.     

Vaginal oestrus during the reproductive and non-reproductive period in European ground squirrels

Most hibernating animals are thought to be monoestrous because reproductive activity is subject to strong time constraints. In previous studies, female European ground squirrels (Spermophilus citellus) turned out to have elevated oestradiol levels during late lactation and after weaning, indicating ovarian activity during summer. Therefore, we monitored vaginal cytology, endocrine changes, and vulval development in semi-free-living female European ground squirrels throughout one active season. Vaginal oestrus, defined by the predominance of cornified cells in smear samples, was found during the mating period shortly after vernal emergence. This phase was followed by metoestrus, characterised by the appearance of leukocytes, and a subsequent anoestrous phase. During weaning or postlactation, a second vaginal oestrus was documented in all experimental females, again followed by a metoestrous and an anoestrous phase lasting until hibernation. In line with the second vaginal oestrus, plasma oestradiol concentrations peaked during postlactation. Progesterone levels were elevated from gestation to postlactation, and titres were marginally higher during vaginal oestrus in summer than in spring. Vulval swelling was more pronounced during the first than the second vaginal oestrus. The second oestrous cycle was non-reproductive, as males were sexually inactive with regressed testes during summer. We assume that the second oestrous cycle and the accompanying endocrine changes have beneficial effects on prehibernatory fattening and reproductive performance in the subsequent season. This might allow females to become oestrous immediately after emergence from hibernation in spring.     

Characterization of the oestrous cycle and mating season of squirrel monkeys from copulatory behaviour.

Observations of the behaviour of squirrel monkeys, including 8 opposite-sex pairs during daily 30-min social encounters and 2 mixed-sex permanent groups during daily 30-min observation sessions, over a 14-month period were used to determine the periodicity of the oestrous cycle and annual mating season. The median and modal length of the oestrous cycle was 8 days, within which copulations were limited to a 1--2 day period. In a cyclic female, plasma progesterone levels over a 24-day period dropped from 85--151 ng/ml to 25 ng/ml 2 days before oestrus. In non-cyclic females plasma progesterone values were less than 15-4 ng/ml. Males exhibited a 6-8--19-7 week 'season' of copulation and ejaculation. The onset of this 'mating season' in August coincided with the annual peak in male body weight (the 'fatted male' phenomenon).     

Progesterone and oestradiol-17 beta concentration profiles throughout the reproductive cycle in harbour seals (Phoca vitulina)

Serum samples of harbour seals kept in captivity were analysed for progesterone and oestradiol-17 beta. The hormone profiles obtained were used to describe a complete reproductive cycle. A clear peak in oestradiol values, indicative of ovulation, was followed by elevated concentrations of progesterone. Implantation probably occurred 3-3.5 months thereafter. Progesterone concentrations rose significantly in the last 3-4 months of gestation, whereas oestradiol concentrations gradually increased after implantation. Lactational oestrus was marked by a peak of oestradiol on average 25 days after parturition and lactation lasted 4-5 weeks. Previous pregnancy had a marked influence on the timing of oestrus; females with offspring started a new reproductive cycle about 14 days later than previously non-pregnant seals. No differences in timing of parturition between the 2 groups were observed. This was probably the result of a flexible period of delayed implantation.     

Effect of oestrogen on Pasteurella pneumotropica in rat vagina

The effects of ovarian hormones on the vaginal population of Pasteurella pneumotropica in rats were investigated. Specified-pathogen-free adult female Wistar-Imamichi rats with a 4 day oestrous cycle were inoculated with P. pneumotropica in the vagina. Cyclic changes in the vaginal population of P. pneumotropica were not observed in ovariectomized rats and the bacterial population was at a similar level to that at normal dioestrus. Administration of oestrogen to ovariectomized rats caused an increase in the numbers of P. pneumotropica and total bacteria in the vagina nearly equal to that at oestrus in intact rats. The numbers of these organisms in the vagina of ovariectomized rats treated with progesterone did not change and were similar to those of control ovariectomized rats treated with sesame oil. Vaginal smears of ovariectomized rats treated with oestrogen were characterized by abundant cornified non-nucleated epithelial cells with many adherent Gram-negative coccobacilli and were similar to smears from intact rats at oestrus. These findings suggest that the proliferation of P. pneumotropica at oestrus in rat vagina may be primarily due to the environment provided by the degeneration of vaginal epithelial cells promoted by oestrogen secretion from the ovaries.     

Plasma binding of oestradiol in progesterone-treated rats

Progesterone treatment of female rats causes an increase in body weight possibly via suppression of oestradiol secretion. This study was carried out to investigate the effect of progesterone on the non-protein bound and hence presumably biologically active fraction of oestradiol. Oestradiol binding to plasma proteins was studied in female Wistar rats during the oestrous cycle and after 12 days of treatment with progesterone (5 mg/day). There was no change in either the unbound fraction of oestradiol or plasma albumin concentrations during the oestrous cycle. Plasma oestradiol concentrations in progesterone-treated rats were similar to those seen during dioestrus, as were the degree of oestrogen binding and the plasma albumin concentrations. Although it was not feasible to calculate unbound concentrations, these results suggest that the increased body weight seen in progesterone-treated rats, and also during pregnancy, may be a result of suppression of unbound oestradiol concentrations to levels similar to those occurring during dioestrus.     

小鼠发情周期卵泡发育动态及其对超数排卵的影响

该文探讨了小鼠发情周期中阴门状态、阴道脱落细胞类型变化规律、卵泡发育规律及其相互关系,并比较了发情周期不同阶段的超排效果。结果表明,采用阴门状态观察法和阴道脱落细胞涂片法,能有效判断小鼠发情周期阶段。卵巢组织切片观察结果表明,在发情周期不同阶段,小鼠的卵泡发育和黄体的生成与消退存在明显的规律性变化;小鼠发情周期中,其阴门状态、阴道脱落细胞种类及卵泡发育动态之间存在相关关系;发情周期不同阶段开始超排的小鼠,其配种见栓率和回收胚胎平均数均存在明显差异,发情前期显著优于发情后期与间情期(P<0.05),并高于发情期,但差异不显著(P>0.05),即阴门状态观察法与阴道脱落细胞涂片法均可用于小鼠发情周期阶段的判断,发情前期为最适宜的小鼠超排时期。     

Oestrous and dioestrous components of the ovarian inhibition on hunger in the rat

Experiments on the effects of oestrus and oestrogens on food intake in the rat showed that food intake is higher after ovariectomy than during the dioestrous phases of the natural cycle, and that it is suppressed by doses of oestradiol too low to produce cornification of the vaginal smear. There may therefore be a tonic inhibition of food intake throughout the oestrous cycle. Another experiment showed that the period of maximal sexual receptivity during the cycle coincided with the period of greatest anorexia, and the loss of receptivity with a rebound hyperphagia.     

Female reproductive behaviour,ovarian hormones and vaginal cytology of the induced ovulator, <Emphasis Type="Italic">Ctenomys talarum</Emphasis>

In the present study, we evaluated whether reproductive condition affects female reproductive behaviour in the induced ovulator Ctenomys talarum. We also explored the effect of the interaction with a male on the reproductive condition of females. To evaluate this, we arranged mating trials and evaluated female reproductive behaviour. Reproductive status of females was evaluated using a combined approach of vaginal smears, urinary progesterone and oestradiol, and ovarian histology. Behaviours denoting attraction (‘male sniff’ and ‘mount attempts’) and mutual courtship behaviours (‘spin’ and copula) were correlated with vaginal cytology before and oestradiol and progesterone levels in urine 12 h after male–female encounter. After 24 h of the interaction, oestradiol levels and vaginal epithelization increased while progesterone levels decreased in soliciting females. C. talarum females’ reproductive behaviour was related to its physiological reproductive state and vaginal cytology. The kind of male interaction, whether couples copulated or remained indifferent affected the later status of females. Females are induced ovulators by mating but male presence and interaction also affected other components of their reproductive physiology such as ovarian hormones and vaginal cytology.     

Social influences on oestrous cycle length and plasma progesterone concentrations in the female lesser mouse lemur (Microcebus murinus)

Plasma progesterone concentrations were recorded during one breeding season in 19 lesser mouse lemur females living in different social conditions. The oestrous cycle length and the progesterone profile mainly depended on the social environment of the female. For totally isolated females, the oestrous cycle lasted 38 +/- 5.7 days and included a 25-30-days spontaneous luteal phase with a progesterone peak about 100 ng/ml between the 20th and 25th days after oestrus, and a prolonged preovulatory period of 10-15 days which could be considered equivalent to the follicular phase of a menstrual cycle. When females were able to communicate through olfactory, visual and auditory signals, the oestrous cycle was significantly lengthened (53.7 +/- 5.9 days). When females had tactile contacts, the oestrous cycle was further lengthened (62.7 +/- 0.8 days). This lengthening of the oestrous cycle was related to an extension of the luteal phase associated with a decrease in progesterone concentrations during this period. In females maintained with one male (paired) or with males and females (heterosexually grouped), large individual variations were shown in cycle lengths or in progesterone concentrations. In these females, cycle lengths and progesterone concentrations were inversely correlated to plasma cortisol concentrations.     

Concentration of steroids in bovine peripheral plasma during the oestrous cycle and the effect of betamethasone treatment.

Testosterone, oestradiol and progesterone were measured in peripheral plasma during the oestrous cycle of 6 heifers. Oestradiol and progesterone results confirmed earlier reports. Concentration of testosterone on the day of oestrus was 40+/-3 pg/ml (mean+/-S.E.M.), and two peaks were detected during the cycle, one 7 days before oestrus (1809+/-603 pg/ml) and the other (78+/- 7 pg/ml) on the day before the onset of oestrus. The concentration of progesterone declined in most cases 1 day after the maximum concentration of testosterone. Betamethasone treatment in 5 heifers extended luteal function by an average of 10 days: plasma androstenedione and oestradiol concentrations were unaltered; cortisol values were depressed for at least 16 days after treatment; testosterone concentrations were lowered by 13+/-2-4% during treatment, and except in one heifer the peak on Day -7 was abolished.     

Cervical mucus and oestrous behaviour responses to oestrogens in sheep: Progesterone-oestrogen relationships and role of progesterone pre-treatment

The final dose of progesterone (5, 10, 20 mg) and time to oestrogen injection relative to the final dose of progesterone (24–72 h) had no significant effect on the production of cervical mucus measured 24 h after the injection of 30 μg oestradiol benzoate (ODB). However, there were significant effects on the behavioural oestrous responses (time from injection of oestrogen to onset of oestrus and duration of oestrus). Time to onset of oestrus increased from 18 to 27.8 h with increasing dose of progesterone (P < 0.001) and decreased from 24.8 to 20 h with increasing time to oestrogen injection (P < 0.05). Conversely, the duration of oestrus decreased from 36.2 to 23.8 h with increasing dose of progesterone (P < 0.001) and increased from 29 to 39 h with increasing time to oestrogen injection (P < 0.01).Ovariectomized ewes became refractory to ODB as measured by the cervical mucus response after the fifth sequential daily injection of 20 μg oestradiol benzoate. Progesterone priming was not required to restore subsequent sensitivity to oestrogen treatment. However, there was a positive linear relationship between length of recovery period and level of response to subsequent treatment.It was concluded that: (1) progesterone pre-treatment or priming is not necessary in the cervical mucus bioassay in ovariectomized ewes; and (2) a period of 8–16 days is needed between assays for normal sensitivity to be regained.     

Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus)

As an integral part of the development of an artificial insemination programme in the captive koala, female reproductive physiology and behaviour were studied. The oestrous cycle in non-mated and mated koalas was characterized by means of behavioural oestrus, morphology of external genitalia and changes in the peripheral plasma concentrations of oestradiol and progestogen. The mean (+/- SEM) duration of the non-mated oestrous cycle and duration of oestrus in 12 koalas was 32.9 +/- 1.1 (n = 22) and 10.3 +/- 0.9 (n = 24) days, respectively. Although the commencement of oestrous behaviour was associated with increasing or high concentrations of oestradiol, there were no consistent changes in the morphology or appearance of the clitoris, pericloacal region, pouch or mammary teats that could be used to characterize the non-mated cycle. As progestogen concentrations remained at basal values throughout the interoestrous period, non-mated cycles were considered non-luteal and presumed anovulatory. After mating of the 12 koalas, six females gave birth with a mean (+/- SEM) gestation of 34.8 +/- 0.3 days, whereas the remaining six non-parturient females returned to oestrus 49.5 +/- 1. 0 days later. After mating, oestrous behaviour ceased and the progestogen profile showed a significant increase in both pregnant and non-parturient females, indicating that a luteal phase had been induced by the physical act of mating. Progestogen concentrations throughout the luteal phase of the pregnant females were significantly higher than those of non-parturient females. Parturition was associated with a decreasing concentration of progestogen, which was increased above that of basal concentrations until 7 days post partum.     

The nature of the sex-linked differences in glutathione peroxidase activity and aerobic oxidation of glutathione in male and female rat liver

1. Glutathione peroxidase activity in the livers of sham-operated female rats was about 60% higher than in similarly treated male rats. The value in the ovariectomized female was about the same as that in the castrated or sham-operated male. 2. Glutathione peroxidase activity changed during the oestrous cycle. The highest value was in oestrus, and was about 50% higher than the lowest activity, which was found in dioestrus. The activity in proestrus and in metoestrus was respectively about 20 and 30% higher than in dioestrus. 3. In the pregnant female 1 or 2 days before term, glutathione peroxidase activity was about 20% higher than that in the female in oestrus. 4. Subcutaneous implants of both oestra-diol and progesterone in the gonadectomized rats increased the glutathione peroxidase activity approximately to the values found in the female at oestrus. 5. The rate of aerobic oxidation of GSH in the female rat liver was about 80% higher than in the male and about 110% higher than in the gonadectomized rats. Treatment of gonadectomized rats with subcutaneous implants of oestradiol and of progesterone increased the rate of oxidation of GSH by about 100%. 6. In the presence of azide the rate of GSH oxidation in the male and in the female was respectively about 3.5- and 2.1-fold that in the absence of azide. In castrated or ovariectomized rats the increase due to the presence of azide was about 2.4-fold. In the gonadectomized rats treated with oestradiol or progesterone the rate of GSH oxidation in the presence of azide was about 2.2-fold that in its absence. 7. The rate of lipid peroxidation in female was 15-30-fold that in male or in gonadectomized rats. Treatment of the gonadectomized rats with oestradiol or with progesterone increased the rate of lipid peroxidation up to values that were even higher than in the female. In the presence of GSH the formation of malonaldehyde from peroxides was virtually eliminated. 8. The results suggest that the sex-linked differences in glutathione peroxidase activity, in the rate of GSH oxidation and in the rate of lipid peroxidation are due to the female sex hormones. 9. It is suggested that both the catalase activity and the rate of hydrogen peroxide formation are higher in the male than in the female. 10. Sex-linked changes in glutathione peroxidase, in the rate of GSH oxidation and in the rate of lipid peroxide formation are discussed in relation to the metabolism of oestrogens in the liver and also to the possible nature of those sex-linked changes.