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ABSTRACT: Fertilization is a crucial step for successful reproduction and can be negatively influenced by stressful situations. It is generally accepted that stress affects reproduction, altering the endocrine profile of the female. An altered hormonal environment where the oocyte is developing could affect critical processes such as fertilization. Using a mixed in vivo-in vitro system, we assessed the ability of the oocyte to undergo fertilization and early development after exposure to blood plasma from sows that had experienced simulated stress through repeated injections of adrenocorticotropic hormone (ACTH) before ovulation (known concentrations of cortisol and reproductive hormones as well as exact ovulation time assessed by ultrasonography). Oocytes (n=926, 7 replicates) collected from abattoir ovaries were matured in TCM-199 with BSA supplemented with hormones (10IEmL(-1) of pregnant mare serum gonadotropin and 5IEmL(-1) of hCG) and insulin-transferrin-selenium (5μLmL(-1)) for 24h, followed by 22h without supplements. During IVF, gametes were exposed to 10% of pooled plasma (n=3 per treatment) collected approximately 1h before ovulation from ACTH-treated sows (A group), nontreated control sows (C group), or media with BSA (B group) for 24h. Fresh semen was added at 5×10(5) cellsmL(-1). Afterward, the remaining cumulus cells and sperm were removed from oocytes by vortexing (1min), and presumptive zygotes were placed in culture medium (porcine zygote medium). Cleavage rate was assessed at 48h post-insemination (hpi) and the embryos (n=433, 7 replicates) were cultured up to Day 7 and stained with Hoechst 33342 (10μgmL(-1)) to count the total number of nuclei. In addition, non-cleaved oocytes were stained at 48hpi with Hoechst to assess sperm-zona binding. Binding to the zona was assessed only in oocytes found to be matured. Statistical analysis was done using Kruskal-Wallis ANOVA and the Mann-Whitney U test. The number of spermatozoa bound to the zona pellucida was higher in the B group, and binding was notably negatively affected in the ACTH group (0.43±0.18, 35.93±2.50, and 3.44±1.04 for the A, B, and C group, respectively; P<0.001). Cleavage rate (over total number of presumptive zygotes) in the A group (30.71±3.76%) was significantly lower than in the control groups (59.93±4.0 and 52.2±5.31% for the B and C group, respectively; P<0.01). Blastocyst rate expressed over the total number of embryos was reduced in the A group (9.40±5.20%) compared with the controls (27.10±5.79 and 25.66±5.28% in the B and C group, respectively; P<0.05). However, no differences were found in the total number of nuclei in the blastocysts. The results suggest that fertilization is a sensitive event that could be negatively influenced by stress, subsequently affecting early embryo development. A reduced number of spermatozoa attached to the zona and a lower number of embryos and lower blastocyst development were observed in the simulated-stress group. Further studies would help to elucidate which (in the oocyte, spermatozoon, or both) mechanisms are being affected by ACTH-simulated stress around fertilization. Data are expressed as mean±SEM.
Reproduction Fertility and Development 01/2011; 23(1):203. · 2.11 Impact Factor
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ABSTRACT: A significant increase in growth of follicles that are selected for ovulation seems to occur on days 14-17 of the estrous cycle. In pigs there is a continuous growth of follicles without appearance of dominant follicles or follicle waves during the estrous cycle. There is a general consensus that a decrease of FSH during the follicular phase is accompanied with the selection of ovulatory follicles and changing from FSH to LH dependence. Development of preovulatory follicles is prevented during lactation mainly due to the inhibition of LH secretion. FSH is not inhibited during lactation and temporary increase in FSH is associated with wave-like follicular growth. Weaning of piglets normally results in increased secretion of LH, which is characterized by a high pulse frequency and low pulse amplitude. The duration of weaning-to-estrus interval is associated with plasma changes in gonadotropins, steroids, inhibin, leptin, IGF-I and insulin. Evidence for a positive role of short elevations in cortisol on LH secretion and ovarian function are accumulating but further studies are still needed to elucidate this issue. The aim of this review was to summarize our current knowledge of endocrinological changes in relation to follicular development during estrous cycle, lactation and after weaning in pigs.
Animal Reproduction (Belo Horizonte). 01/2009; 6(1):135-143.
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ABSTRACT: Systems with loose-housed sows have become common. Regrouping, which is commonly done after weaning and may coincide with many important reproductive events, causes stressful situations with elevated blood cortisol concentrations. Depending on group size, approximately 2-7 d are required for a new group of sows to become relatively stable. In a series of studies, the social stress after regrouping was simulated with repeated adrenocorticotrophic hormone (ACTH) treatments for approximately 48h. Sows were allocated into control and experimental groups, fitted with jugular catheters, and blood samples were collected every 2 or 4h. Follicular development and ovulation were monitored by transrectal ultrasonography every 4h. Simulated stress during pro-estrus prolonged estrus and disturbed the follicular growth and ovulation. Giving ACTH during estrus elevated concentrations of cortisol and progesterone, and changed the intraluminal environment, including exaggerated amounts of mucus in the UTJ and isthmus. Although ACTH had no effect on the time of ovulation (relative to onset of standing estrus), or on embryo development, fewer oocytes/embryos were retrieved from the ACTH group than from the control group (51% vs. 81%, P<0.05), and there was a tendency towards faster embryo transportation to the uterus. Short-term fasting after ovulation had an unfavourable effect on sperm numbers in UTJ/isthmus, cleavage rate of fertilized ova, as well as ova transport through the isthmic part of the oviduct. Treatment with ACTH after ovulation reduced numbers of spermatozoa at the zona pellucida and retarded cleavage rate of fertilized ova. Therefore, the timing of stress seemed to be an important factor regarding effects on reproductive events.
Theriogenology 10/2008; 70(8):1197-201. · 1.96 Impact Factor
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ABSTRACT: This study investigated the effect of continuous elevated cortisol concentrations during standing oestrus on time of ovulation and patterns of progesterone, oestradiol and luteinising hormone (LH) in sows. The elevation of cortisol concentrations was achieved through repeated intravenous injections of synthetic adrenocorticotropic hormone (ACTH) every 2 h for approximately 48 h, from the onset of the second standing oestrus after weaning. Treatment was terminated when ovulation was detected (monitored by transrectal ultrasonography every 4h) or when the sow had received a maximum of 24 injections. The dose of ACTH (2.5 microg/kg) was chosen to mimic the cortisol concentrations seen during mixing of unfamiliar sows. The sows (n=14) were surgically fitted with jugular vein catheters and randomly divided into a control (C group where only NaCl solution were injected) or an ACTH group. Blood samples were collected every 2 h. In parallel with the blood sampling, saliva samples for cortisol analyses were taken from eight sows before onset of treatment and from four of the sows during treatment. There was no difference in time from onset of standing oestrus to ovulation between the two groups. The interval between the peaks of oestradiol and LH to ovulation was prolonged in the ACTH group compared to the C group (p<0.05), with a tendency towards an earlier decline of oestradiol in the ACTH group. Cortisol and progesterone concentrations were significantly elevated during treatment in the ACTH group (p<0.001), with cortisol peak concentrations occurring between 40 and 80 min after each ACTH injection. Cortisol concentrations in saliva and plasma were highly correlated (p<0.001). In conclusion, elevated cortisol concentrations from the onset of standing oestrus increase progesterone concentrations and prolong the interval between oestradiol and LH peaks to ovulation, the latter possible due to an early decline in oestradiol concentrations and a change of the LH peak outline. The effect these hormonal changes have on reproductive performance need to be further investigated. Saliva samples might be a useful and non-invasive method to assess cortisol concentrations in sows.
Animal reproduction science 01/2008; 110(1-2):172-85. · 1.56 Impact Factor
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ABSTRACT: This study was conducted to assess the effects of ACTH injections on the early development of embryos and their transportation to the uterus. Fifteen sows were monitored for ovulation using transrectal ultrasonography during the first two oestrous periods after weaning. The sows were randomly divided into a control group (C group, n = 8) and an ACTH-treated group (ACTH group, n = 7), and were all surgically fitted with intra-jugular catheters. From the onset of the second standing oestrus after weaning, the sows were injected (NaCl/synthetic ACTH) every 4 h. Blood samples were collected immediately before and 45 min after each injection. All sows were inseminated once 10-33 h before ovulation in their second oestrus after weaning. At 48 (n = 4) or 60 (n = 11) h after ovulation during their second oestrus, the sows were killed and the embryos retrieved from the oviduct and uterus. The embryos were counted and compared with the number of corpora lutea, cleavage rate was noted and, finally, the embryos were prepared for confocal laser scanning microscopy and transmission electron microscopy. There was no difference between the groups regarding cleavage rate, the cytoskeleton, or the number of active nucleoli. However, the ACTH group had significantly (p < 0.05) fewer ova/embryos retrieved (51%) than the C group (81%), and there was a tendency towards faster transportation to the uterus in the ACTH group, possibly because of high progesterone concentrations during treatment. To conclude, administration of ACTH every 4 h from onset of oestrus to 48 h caused significant loss of oocytes or embryos, and possibly faster transportation through the oviduct.
Reproduction in Domestic Animals 04/2007; 42(2):118-25. · 1.36 Impact Factor
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ABSTRACT: This study investigated whether injections of ACTH for 48 h, from the onset of the second standing estrus after weaning, had any impact on time of ovulation and patterns of progesterone, estradiol, luteinizing hormone (LH), and inhibin alpha. The studied sows (n=15) were fitted with jugular vein catheters and randomly divided into a control (C group) and an ACTH group. From the onset of standing estrus, the sows were injected (NaCl or synthetic ACTH, 5 microg/kg) every 4h; blood samples were collected immediately before and 45 min after each injection. Ovulation was monitored using ultrasonography. The ACTH-group sows stopped displaying signs of standing estrus sooner after ovulation in their second estrus, but no impact was found on time of ovulation. There were no significant differences in the intervals between LH peak, estradiol peak, and the onset of standing estrus between the C and ACTH groups. The cortisol and progesterone concentrations were significantly elevated (p<0.001) in samples taken 45 min after ACTH injection. There were minor differences in estradiol and LH concentrations between the groups. Overall inhibin alpha concentrations were significantly higher during the treatment period in the ACTH than in the C group, but there were no significant differences between samples taken either 45 min or 4h after injection. In conclusion, injections of synthetic ACTH during estrus in the sow apparently disturb the duration of signs of standing estrus and the hormonal pattern of progesterone, and possibly of inhibin alpha, estradiol and LH.
Domestic Animal Endocrinology 03/2007; 32(2):122-37. · 2.06 Impact Factor
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ABSTRACT: Sows housed in freely moving groups have elevated cortisol levels until the rank order is established, which takes place within approximately 48 h. The aim of this investigation was to study the effect of repeated administration of synthetic adrenocorticotropic hormone (ACTH; Synacthen Depot), during the follicular phase (pro-oestrus) on oestrus, ovulation and endocrine parameters. Four multiparous sows were used. Follicular growth and ovulation were recorded by ultrasonography. The first oestrous cycle after weaning was used as control cycle. Onset of oestrus in the sow occurs 3-4 days after the time when plasma progesterone reaches a concentration of 8 nmol/l. The progesterone profile in the control cycle of the individual sow was used for estimation when the ACTH injections should start. In the third pro-oestrus ACTH (2.5 microg/kg) was given via an indwelling catheter every 2 h for 48 h. The sows were euthanased 4-6 days after onset of the third oestrus and the ovaries were examined. Cortisol levels were elevated during the treatment period (p < 0.05). The second cycle, in which the sows were injected with ACTH, was prolonged with 2.5 days compared with the control cycle (p < 0.05). The oestradiol pattern during oestrus was similar in the control and the treatment cycle in ovulating sows. Three sows had ovulated (fresh corpora lutea), but the ovaries contained additionally one or several luteinized follicles/cysts. In conclusion, ACTH administration during pro-oestrus caused a prolongation of the oestrous cycle and a disturbed follicular development.
Reproduction in Domestic Animals 02/2007; 42(1):100-4. · 1.36 Impact Factor
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ABSTRACT: This study investigated whether injections of synthetic ACTH (simulating short-term stress) in sows during standing oestrus have a negative effect on spermatozoa and the local intraluminal environment in the utero-tubal junction (UTJ) and isthmus. Seven of the 14 sows were given ACTH through a jugular catheter every 2 h from the onset of standing oestrus until the sow ovulated (ACTH-group), while the other seven sows were given NaCl solution (C-group). All sows were artificially inseminated before ovulation. Six hours after ovulation (detected with transrectal ultrasonography) the sows were anaesthetised, the right oviduct was fixed in toto by vascular perfusion with glutaraldehyde, and the UTJ and specimens from the isthmus were prepared for scanning electron microscopy (SEM). SEM revealed that a seemingly viable population of spermatozoa remained in the UTJ 6 h after ovulation. A majority of sows in the ACTH-group had moderately to exaggerated amounts of mucus in the intraluminal environment of the sperm reservoir. In conclusion, stress simulated by exogenous ACTH in sows may alter the intraluminal environment of the sperm reservoir.
Animal Reproduction Science 08/2006; 93(3-4):231-45. · 1.75 Impact Factor
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ABSTRACT: The objective of the study was to investigate if short-term stress in sows (simulated by injections of synthetic adrenocorticotrophic hormone (ACTH)) during standing oestrus had a negative effect on the local environment in the utero-tubal junction (UTJ) and isthmus and the distribution of spermatozoa in these segments. Fourteen sows were monitored for ovulation using ultrasonography in two consecutive oestruses. The sows were fitted with jugular catheters and, from onset of the second oestrus, blood samples were collected every second hour. In the 2nd oestrus, seven sows were given ACTH every second hour, from the onset of standing oestrus until the sow ovulated (ACTH-group), whereas the other seven sows remained as controls (C-group) and were given NaCl solution. The sows were artificially inseminated 16-18 h before expected ovulation. Six hours after ovulation the sows were anaesthetised, and blood samples were repeatedly taken from veins draining the uterus and the UTJ-isthmus, respectively. This oviduct was thereafter removed and divided in four adjacent sections consisting of: (i) the UTJ, (ii) the first, and (iii) the second isthmus segment prior to (iv), the ampullary-isthmic junction (AIJ) and the ampulla. The three first-mentioned segments were flushed to retrieve spermatozoa, whereas the last one was flushed to collect oocytes/ova. The number of spermatozoa attached to the zona pellucida was counted. The concentrations of cortisol in jugular blood of the ACTH-group sows during the time of ACTH-injections were significantly higher than of the C-group sows (p<0.05), as were the levels of progesterone (p<0.001). Progesterone and cortisol concentrations measured in the blood samples draining the UTJ-isthmic region 6 h after ovulation did not significantly differ between the groups, but the C-group displayed significantly higher concentrations of progesterone in the UTJ-isthmic region compared with the levels measured in parallel samples taken of jugular blood (p<0.01). The C-group, but not the ACTH-group, also displayed a significant elevation in progesterone concentration 6h after ovulation compared with the basal levels before ovulation (p<0.01). Numbers of retrieved spermatozoa were not significantly different between the C-group and the ACTH-group. However, there was a tendency for a larger number of spermatozoa among sows in the ACTH-group, especially in the isthmic segment adjacent to the AIJ. In conclusion, simulated stress induced by injections of ACTH during standing oestrus results in elevated concentrations of progesterone before ovulation and may interfere with the rise of progesterone after ovulation. However, ACTH-injections appeared to augment transport of spermatozoa through the female genital tract of pigs.
Animal Reproduction Science 03/2006; 92(1-2):107-22. · 1.75 Impact Factor
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ABSTRACT: The hormonal interactions of the hypothalamic-pituitary-ovarian-uterine axis are accountable for a normal reproduction in female pigs. It is of importance to have knowledge of estrous symptoms and hormonal profiles around ovulation. The introduction of the transrectal ultrasonography in sows has given us the possibility to study ovarian activity in conscious animals and relate the timing of estrus to ovulation. Combining this technique with measuring of several hormones like luteinizing hormone (LH), follicle-stimulating hormone (FSH), inhibin, estradiol, progesterone, insulin-like growth hormone I (IGF-I), prostaglandin F2alpha (PGF2alpha) metabolite, oxytocin, facilitate our knowledge about the sequence of ovarian events. Evidence suggests that activation of the hypothalamic-pituitary-adrenal axis may hamper the normal gonadotropin secretion and in consequence, the ovarian function. The metabolic status during lactation, weaning of piglets and social stress might affect onset of ovarian activity and the related estrous behavior. The role of seminal plasma, artificial insemination and presence of the boar might also be included as factors regulating the temporal kinetics of ovulation, corpus luteum development, uterine function and steroid production in the ovary. Studies using a simulated stress by means of adrenocorticotrophic hormone (ACTH) administration or food deprivation are tools in understanding how the ovary is susceptible to impairment. The intention of this paper is to review current knowledge concerning the endocrine aspects of normal and stress-influenced ovarian function in pigs.
Domestic Animal Endocrinology 09/2005; 29(2):347-61. · 2.06 Impact Factor
