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1.
Sexually mature gilts (n = 20) were actively immunized against GnRH. Primary and booster immunizations of GnRH conjugated to bovine serum albumin induced production of antibodies in all gilts. Nineteen of the gilts became acyclic with suppressed concentrations of gonadotropins and estradiol. Intravenous challenges with 100 micrograms GnRH and 5 micrograms D-(Ala6, des-Gly-NH2(10)) ethylamide GnRH (a GnRH agonist that did not cross-react with antibodies produced by the gilts) caused release of LH and FSH, indicating maintenance of secretory capacity of pituitary gonadotropes in the immunized animals. Gilts were given 100 ng GnRH agonist at 2-h intervals for 72 h (n = 4) or 144 h (n = 10) or did not receive agonist (n = 5). Blood samples were taken every 6 h, and detectable concentrations of LH were observed in 42% and 52% of samples taken from gilts treated with or without agonist. In contrast, serum concentrations of FSH and estradiol were undetectable. Reproductive tracts and anterior pituitaries were taken from gilts at the conclusion of pulsatile administration of GnRH agonist or at 144 h for controls. Pituitary concentration of LH and FSH, uterine wet and dry weight, and size of the uterus were similar among groups. Paired ovarian weights for treated gilts pulsed with GnRH agonist for 72 h were heavier (P less than .05); however, ovaries from all immunized gilts were atrophied without follicular structures.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
The prolific Romanov (R, ovulation rate = 3) and non-prolific Ile-de-France (IF, ovulation rate = 1) breeds were compared for their ovarian sensitivity to gonadotropins and IGF-I before puberty. For this purpose, the effects of in vivo immunization against GnRH on populations of ovarian follicles and in vitro sensitivity of granulosa cells to FSH and IGF-I were studied in prepuberal lambs from both breeds. Seventeen prepuberal lambs of each breed were actively immunized against GnRH between 3 wk and 6 mo of age. Relative to untreated lambs, FSH levels at 4, 5, and 6 mo of age were (respectively) 41%, 25%, and 29% for IF, and 43%, 24%, and 36% for R lambs. In a first experiment, histological analysis of ovaries was performed. Immunization treatment decreased the number of small (100–390 μm in diameter) and large size follicles (<1500 μm) in both breeds at 6 mo of age. In both breeds, gonadotropin (FSH - LH -hCG) treatment increased the number of large size follicles (<1500 μm in diameter) and induced the formation of preovulatory follicles in immunized as well as untreated lambs. The ovulation rate was less in immunized animals, but it was not different between breeds. In a second experiment, the effects of FSH and IGF-I were studied on granulosa cells from follicles between 1000 and 2000 μm in diameter. In both breeds, IGF-I increased granulosa cell proliferation, but enhanced progesterone secretion was observed only in R lambs after FSH and IGF-I stimulation. Granulosa cell response to FSH treatment was lost by immunization, whereas response to IGF-I remained unchanged in both breeds. These results indicate that long-term immunization of prepuberal lambs against GnRH reduced systemic concentrations of FSH, follicular development, and response to gonadotropins in vivo, similarly in the prolific R and the non-prolific IF breed. However, granulosa cells from R lambs had higher steroidogenic capacities and were more responsive to FSH. In addition, these results suggest that IGF-I could play an important role in regulating growth of small follicles both in immunized and non-immunized lambs.  相似文献   

3.
The objective of this experiment was to evaluate the effects of active immunization against 2 GnRH isoforms on gonadotropin secretion and testicular function in pigs. Synthetic chicken (c) GnRH-II and lamprey (l) GnRH-III peptides, with the common pGlu-His-Trp-Ser sequence at the N-terminal omitted, were conjugated to BSA. Forty-eight male piglets were randomly assigned to 1 of 4 treatments. Pigs on treatment 1 were actively immunized against cGnRH-II, whereas pigs on treatment 2 were actively immunized against lGnRH-III. Control pigs on treatment 3 were actively immunized against the carrier protein (BSA), and pigs on treatment 4 were castrated and actively immunized against BSA. The BSA conjugate was emulsified in Freund's Incomplete Adjuvant and diethylaminoethyldextran. Primary immunization was given at 13 wk of age (WOA) with booster immunizations given at 16 and 19 WOA. Body weight and plasma samples were collected weekly beginning at 11 WOA. Treatments did not affect BW during the experimental period. Antibody titers were increased in animals immunized against cGnRH-II and lGnRH-III (P < 0.001). Cross-reactivity of the antibodies to mammalian GnRH or between cGnRH-II and lGnRH-III was minimal. Concentrations of testosterone were maximal in control boars (treatment 3) and minimal in control barrows (treatment 4) and immunized pigs (treatment x week; P < 0.01). Immunized animals had concentrations of LH (P < 0.001) and FSH (treatment x week; P < 0.03) that were less than control barrows and similar to control boars. At the end of the experiment, intact (noncastrated) pigs were exsanguinated. Testes were removed immediately; Leydig cells were isolated and treated with 0, 1, or 10 ng/mL of LH. There was an LH x GnRH treatment effect on testosterone concentrations (P < 0.03), indicating that Leydig cells were sensitive to the immunization protocol and doses of LH. Taken together, these data suggest that immunization against GnRH isoforms decreased gonadotropin secretion compared with control barrows. Additionally, immunization against cGnRH-II and lGnRH-III reduced the ability of Leydig cells to respond to LH challenges.  相似文献   

4.
Five lighthorse mares were actively immunized against gonadotropin releasing hormone (GnRH) conjugated to bovine serum albumin (BSA) to study the involvement of GnRH in luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion following ovariectomy (OVX) and after administration of testosterone propionate (TP). Five mares immunized against BSA served as controls. Immunizations were started on November 1, and OVX was performed in June (d 1). All mares were treated with TP from d 50 to 59 after OVX. On the day of OVX, concentrations of LH were lower (P less than .05) in GnRH-immunized mares than in BSA-immunized mares and were generally nondetectable; FSH concentrations were reduced (P less than .05) by 50% in GnRH-immunized mares relative to BSA-immunized mares. In contrast to BSA-immunized mares, plasma concentrations of LH or FSH did not increase after OVX in GnRH-immunized mares. The LH response to GnRH analog (less than .1% cross-reactive with GnRH antibodies) on d 50 was reduced (P less than .05) by 97% in GnRH-immunized mares relative to BSA-immunized mares, whereas the FSH response was similar for both groups. Treatment with TP for 10 d reduced (P less than .01) the LH response and increased (P less than .01) the FSH response to GnRH analog in BSA-immunized mares, but it had no effect (P greater than .1) on the response of either gonadotropin in GnRH-immunized mares.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
This experiment was conducted to compare the ability of USDA porcine FSH-B-1 (pFSH), USDA porcine LH-B-1 (pLH), and pregnant mare's serum gonadotropin (PMSG) to grow large follicles and induce granulosal cell aromatase activity in prepuberal gilts. Twenty-four gilts (164 d old) received one of four treatments by i.m. injection: 1) saline once, n = 8; 2) pFSH (8 micrograms/kg BW, nine times at 8-h intervals), n = 5; 3) pLH (2 micrograms/kg BW, nine times at 8-h intervals), n = 6; or 4) PMSG (15 IU/kg BW, once), n = 5. At slaughter, 72 h after the first injection, the ovaries to saline-treated gilts contained an average of 104 surface antral follicles 1 to 3 mm in diameter. compared to treatment with saline, pFSH increased (P less than .05) the number of follicles 46%, whereas pLH or PMSG decreased (P less than .05) the number by 70 and 84%, respectively. Compared with saline, treatment with PMSG or pLH induced growth of large follicles (7 to 9 mm) (10.8 and 4.8 follicles/gilt, respectively), increased plasma estrogen, increased granulosal cell aromatase activity, and decreased plasma FSH by 51 and 69%; treatment with pFSH had no significant effect on these traits. Results indicate that injected pFSH did not cause growth of large follicles or induce granulosal cell aromatase activity in prepuberal gilts. In contrast, LH initiated growth and increased granulosal cell aromatase activity in a small number of follicles and accelerated atresia among the remaining follicles.  相似文献   

6.
Fifty crossbred gilts immunized against bovine serum albumin (BSA) or androstenedione conjugated to BSA (AD) were used in three experiments. Primary immunizations were given at 120 d of age and boosters at 148 and 176 d. Gilts were moved to pens containing four to five animals each and exposed to boars beginning at 180 d of age. Immunization against AD did not affect age at puberty, percentage of gilts exhibiting estrus or duration of first estrous cycle. Over the three experiments, ovulation rate was 24% greater for AD-immunized gilts than for controls, and the number of corpora lutea was related positively (r = .82) to the log of the antibody titer. Number of ovulations decreased as interval from booster immunization to onset of estrus increased. During diestrus of the first estrous cycle, gilts immunized against AD had more follicles 5 to 10 mm in diameter, more total ovarian follicles and more total ovarian structures (corpora lutea plus follicles) than controls. Immunization against AD increased the frequency of LH pulses on d 16 but not on d 17 or 18, of the estrous cycle. However, average serum concentrations of LH, FSH and estradiol from 5 d before until 2 d after expected estrus were not different between treatment groups. Concentrations of AD in follicles 4 to 6 and greater than 7 mm in diameter were greater in gilts immunized against AD. Mean serum progesterone was higher on d 9 and 12 after mating in AD immunized gilts than in controls. Immunization against AD had no effect on maintenance of pregnancy or embryo survival rate.  相似文献   

7.
The hypothesis of the present study is that active immunization of cows against inhibin would neutralize endogenous inhibin, increase circulating levels of follicle stimulating hormone, and subsequently affect follicular dynamics and the ovulation rate during the estrous cycle. Thirteen cows were immunized against inhibin alpha-subunit and, 6 cows were immunized with a placebo. Both groups were given 4 booster immunizations 7, 14, 21, and 34 weeks after the primary injection. Ovaries were examined daily after the 2nd, 3rd, and 4th booster immunizations by transrectal ultrasonography for 25 days. After the 4th booster immunization, blood samples were collected daily for one complete estrous cycle to measure FSH and LH. The results showed that the immunized cows generated antibodies against inhibin, and that they had higher FSH levels compared with the controls. The number of follicular waves during the estrous cycle was higher in the immunized cows (3 or 4 waves) than in the controls (2 or 3 waves). Moreover, the immunized cows had a greater number of follicles during the estrous cycle compared with the control cows. The maximum number of follicles was 14.8 +/- 1.7 vs 5.4 +/- 0.2 in inhibin-immunized and control cows, respectively, during the first follicular wave and 13.9 +/- 1.9 vs 5.6 +/- 0.7, respectively, during the ovulatory wave. Multiple ovulations were increased in the immunized cows. However, the ovulation rate varied greatly in the immunized animals. In conclusion, immunization against inhibin increased FSH secretions during the estrous cycle in the cows. Moreover, the immunized cows had a greater number of follicular waves during the estrous cycle and a greater number of follicles, and this could be used as a potential source of oocytes for use in IVF/embryo transfer programs.  相似文献   

8.
To determine whether pituitary concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) or hypothalamic content of gonadotropin releasing hormone (GnRH) change before puberty, 40 prepubertal gilts averaging 7 mo of age were slaughtered before or on the second, third or fourth day after relocation and boar exposure. Some gilts responded to relocation and boar exposure as indicated by swollen vulvae, turgid uteri and enlarged ovarian follicles at the time of slaughter. Pituitary concentrations of LH and FSH and hypothalamic content of GnRH were similar between gilts that responded to relocation and boar exposure and gilts that did not respond. In addition, boar exposure and relocation had no effect on pituitary concentrations of LH and FSH or on hypothalamic content of GnRH. To determine whether pituitary responsiveness to GnRH changes before puberty, a third experiment was conducted in which 72 gilts were injected with 400 micrograms of GnRH either before or on the second, third or fourth day after relocation and boar exposure. In gilts that subsequently responded (i.e., ovulated) as a result of relocation and boar exposure, pituitary responsiveness to GnRH was reduced as compared with gilts that failed to ovulate after relocation and boar exposure. Peak concentrations of serum LH after GnRH injection were 4.6 +/- 1.3 vs 9.8 +/- .8 ng/ml for responders vs nonresponders. Peak serum FSH after GnRH injection was also lower for responders than for nonresponders (29.5 +/- 4.2 vs 41.2 +/- 2.4 ng/ml). When compared with controls, relocation and boar exposure did not significantly affect GnRH-induced release of LH and FSH.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
An experiment was conducted to evaluate the effect of exogenous gonadotropin releasing hormone (GnRH) on ovulation and embryonic survival in pubertal gilts. Gilts were assigned in replicates to a control (n = 10) and treatment (n = 10) group. Treatment consisted of an iv injection of 200 micrograms of GnRH immediately after initial mating on the first day of detected estrus. Control gilts were similarly injected with physiological saline. Blood samples were collected from the anterior vena cava immediately prior to injection, thereafter at 15-min intervals for 90 min, and subsequently, before slaughter on d 30 of gestation. Serum samples were analyzed for luteinizing hormone (LH) and progesterone by radioimmunoassay. Treatment with GnRH increased the quantity of LH released (P less than .05), with highest serum concentrations (ng/ml, means +/- SE) of gonadotropin in treated gilts (17.3 +/- 3.5) occurring at 75 min post-injection. In control gilts, serum concentrations of LH were not affected by injection of saline. Mean number of ovulations in treated gilts was also greater (P less than .05) than that of control animals (14.5 +/- .7 vs 12.1 +/- .6). However, treatment with GnRH did not enhance the number of attached conceptuses (normal and degenerating) present (treated, 10.9 +/- .9 vs control, 10.5 +/- .7) nor the percentage of viable fetuses (treated, 74.7 +/- 6.9 vs control, 83.5 +/- 5.0%) on d 30 of gestation. Although GnRH increased ovulation rate, mean weight of corpora lutea of treated and control gilts did not differ (402.8 +/- 16.3 vs 389.5 +/- 11.3 mg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
Plasma prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in groups of eight gilts sampled every 20 min for 6 h at about 2-wk intervals between 15 and 192 d of age. The PRL levels were high at 15 and 28 d, declined at 40 d just after weaning and then rose slowly until 192 d of age. The number of LH pulses during 6 h was higher between 83 and 125 d than at the other periods. Magnitude of LH pulses was highest at 15 d, constant from 54 to 125 d, fell at 137 d and remained low until 192 d. Plasma FSH was high from 15 to 125 d, with a maximum at 54 d. It declined slowly until 168 d and did not change thereafter. Estrogen excretion was estimated from urine excretion of estrone (E1; conjugated plus nonconjugated E1) per 24 h from 40 d until puberty in three gilts and at 156 and 174 d in two other animals. The E1 excretion increased with age and four levels were described before peak values with the onset of first estrus. The first increase in E1 excretion occurred between 68 and 110 d, when antral follicles appeared in the ovaries. It was subsequent to the highest levels of FSH and concomitant with the increased frequency of LH pulses. The drop in levels of both gonadotropins after 125 d probably corresponded to the development of the negative feedback as a result of greater ovarian activity in these gilts.  相似文献   

11.
The influence of varying doses of human chorionic gonadotropin (hCG) on the preovulatory luteinizing hormone (LH) surge, estradiol-17 beta (E2) and progesterone (P4) was studied in synchronized gilts. Altrenogest (AT) was fed (15 mg X head-1 X d-1) to 24 cyclic gilts for 14 d. Pregnant mares serum gonadotropin (PMSG; 750 IU) was given im on the last day of AT feeding. The gilts were then assigned to one of four groups (n = 6): saline (I), 500 IU hCG (II), 1,000 IU hCG (III) and 1,500 IU hCG (IV). Human chorionic gonadotropin or saline was injected im 72 h after PMSG. No differences in ovulation rate or time from last feeding of AT to occurrence of estrus were observed. All gilts in Groups I and II expressed a preovulatory LH surge compared with only four of six and three of six in Groups III and IV, respectively. All groups treated with hCG showed a rapid drop (P less than .01) in plasma levels of E2 11, 17, 23 h after hCG injection when compared with the control group (35 h). The hCG-treated gilts exhibited elevated P4 concentrations 12 h earlier than the control group (3.1 +/- .5, 3.4 +/- .72, 3.1 +/- .10 ng/ml in groups II, III and IV at 60 h post-hCG vs .9 +/- .08 ng/ml in group I; P less than .05). These studies demonstrate that injections of ovulatory doses of hCG (500 to 1,500 IU) had three distinct effects on events concomitant with occurrence of estrus in gilts: decreased secretion of E2 immediately after hCG administration, failure to observe a preovulatory LH surge in some treated animals and earlier production of P4 by newly developed corpora lutea.  相似文献   

12.
Two experiments were conducted to determine the effects of pregnant mare's serum gonadotropin (PMSG) on follicular populations and ovulation rates in prepuberal gilts with grape-type (GT) and honeycomb-type (HT) ovaries. The follicular populations were determined at 170 d of age (d 0) and 19 d after PMSG (d 19). In Exp. 1, the mean number of macroscopic follicles of Classes 2 and 3 was greater (P less than .05) in GT (n = 11) than in HT (n = 32) ovaries at d 0, whereas the mean number of those of Class 1 was greater (P less than .05) in HT ovaries. At d 19, no difference was observed between the two ovarian types for any class of follicles. The PMSG-induced ovulation rates were comparable between the two ovarian types (8.3 vs 7.9, GT vs HT, respectively; P greater than .10). In Exp. 2, the microscopic follicular populations were determined on right and left ovaries removed, respectively, on d 0 and 19. At d 0, GT ovaries (n = 5) contained a greater number of Class 5 nonatretic (P less than .01) and atretic (P less than .02) follicles than did HT ovaries (n = 5), whereas at d 19 the mean number was not statistically different between the two ovarian types (P greater than .10). In contrast, gilts with HT ovaries contained a greater (P less than .01) number of Class 4 atretic follicles than gilts with GT ovaries at d 0, whereas at d 19 the mean number was not statistically different between the two ovarian types (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
The effect of pregnant mare serum gonadotropin (PMSG) or estradiol cyclopentylpropionate (EC) on the induction of estrus, duration of estrus, and serum progesterone concentration after estrus was evaluated in 8 gilts with delayed puberty. Four gilts were given 500 IU of PMSG IM and 4 were given 2 mg of EC, IM. The inactive status of the ovaries at the time of treatment was verified by serum progesterone values of less than 0.5 ng/ml in serial samples collected before treatment. The 4 EC-treated gilts came into estrus at a mean of 3.5 days after treatment, but 1 of the gilts did not form corpora lutea. Three PMSG-treated gilts came into estrus at a mean of 4.0 days after treatment. The remaining PMSG-treated gilt remained anestrus and did not form corpora lutea. The mean duration of estrus in EC-treated gilts was 5.25 days compared with 2.0 days for PMSG-treated gilts (P less than 0.05). Serum progesterone concentrations were higher in PMSG-treated gilts than in EC-treated gilts at 8, 11, and 17 days after treatment (P less than 0.05).  相似文献   

14.
Two experiments were performed to examine the influence of exogenous growth hormone on the reproductive axis in gilts. Experiment one employed 26 Yorkshire × Landrace prepubertal gilts, which were selected at 150 d and 86.5 ± 1.5 kg bodyweight (BW) and assigned equally to two treatments. Gilts received injections of either porcine growth hormone at 90 μg/kg BW, or vehicle buffer, from 150 to 159 d. At 154 d gilts received 500 IU PMSG, followed 96 hr later by 250 IU hCG. Gilts were slaughtered at 163 days and their ovaries recovered to determine ovulatory status. In each treatment, gilts failed to show any ovarian response to PMSG/hCG. All remaining control gilts ovulated and their ovaries appeared morphologically normal. In gilts receiving exogenous growth hormone, fewer ovaries (4/11, P<.01) appeared morphologically normal. The ovaries of all other growth hormone injected gilts had very large (12–25 mm) non-luteinized follicles. In experiment two, 20 prepubertal Yorkshire × Landrace gilts were selected at 138 days and 85 kg BW. These gilts received injections of growth hormone at 90 μg/kg BW (n=9) or vehicle (n=11) from 138 to 147 days. At 143 days, all gilts were given an injection of estradiol benzoate (EB) at 15 μg/kg BW. Blood samples were taken at the time of EB injection, at 24 and 36 hr and then at 6 hr intervals until 78 hr. All samples were assayed for serum LH concentrations. The EB induced LH peak height was lower (P<.04) in gilts receiving exogenous growth hormone than in controls. The results presented indicate that the daily injection of growth hormone at 90 μg/kg BW reduced the estradiol-induced release of LH in addition to reducing the number of corpora lutea in gonadotrophin stimulated gilts.  相似文献   

15.
The effect of glucocorticoids on early follicular growth in sows undergoing normal estrous cycles was evaluated by administration of dexamethasone during the middle of the luteal phase. Plasma specimens were obtained for measurement of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and estradiol-17 beta concentrations. Fifteen sows were used. Control sows (n = 5) were given physiologic saline solution twice daily from day 9 to day 14 of the estrous cycle. Sows of the second group (n = 5) were given dexamethasone (30 micrograms/kg of body weight, IM) similarly, and those of the third group (n = 5) were given dexamethasone plus gonadotropin-releasing hormone (GnRH; 50 micrograms at 6-hour intervals, IV). Plasma specimens, obtained twice daily from day 8 through day 26, indicated that progesterone production and luteal regression were not inhibited by any of the 3 treatment regimens. Although preovulatory plasma estradiol concentration increased in control sows, such was not observed in the sows treated with dexamethasone or dexamethasone plus GnRH (P less than 0.01). Ovulation, with formation of corpora lutea, occurred in gilts given saline solution. Dexamethasone administration resulted in persistence of 19 to 41 follicles/ovary (2 to 4 mm in diameter), and dexamethasone-plus-GnRH treatment resulted in 6 to 18 follicles/ovary (5 to 6 mm in diameter). Plasma was obtained at 15-minute intervals for 12 hours to compare the effect of treatment on hormone concentrations on day 12 of the estrous cycle with the values on day 8.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

16.
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17.
The effects of unilateral castration (UC) and induced unilateral cryptorchidism (UCR) on basal plasma luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone, and on the responses of these hormones to gonadotropin releasing hormone (GnRH), were investigated in bulls altered at 3, 6 or 9 months of age. Blood plasma was collected before and after GnRH (200 micrograms) stimulation approximately 1 year following gonadal manipulation. Neither mean baseline concentrations nor GnRH-induced increases in plasma testosterone were altered (P greater than .1) by hemicastration or UCR (P greater than .1). Both mean baseline LH and GnRH-induced LH release were greater (P less than .05) in bulls altered at 3 months of age than in bulls altered at 9 months of age. UC increased (P less than .05) plasma LH response to GnRH over that observed in intact bulls, but not above that in UCR bulls. UCR had no detectable effect on either baseline concentrations or GnRH-stimulated LH release. FSH was increased (P less than .05) in hemicastrates, while UCR had a variable effect on peripheral FSH: FSH was reduced (P less than .05) in UCR animals altered at 3 months of age but increased (P less than .05) in UCR bulls altered at both 6 and 9 months of age when compared to FSH in intact bulls. The results indicate that, compared with intact bulls, UC bulls release increased amounts of both gonadotropins but similar amounts of testosterone in response to GnRH stimulation. UCR had a variable effect on FSH release and did not alter either LH or testosterone.  相似文献   

18.
Thirty-four gilts in two experiments were fed altrenogest for 18 d to block spontaneous growth of ovulatory follicles after luteolysis. They were injected with estradiol or charcoal-extracted porcine follicular fluid (pFF) to determine 1) whether gonadotropin secretion could be depressed and 2) whether exposure to reduced levels of gonadotropins would result in decreased numbers of medium follicles (3 to 6 mm in diameter). Gilts in Exp. 1 received treatments in a 2 X 2 X 2 factorial arrangement starting 48 h before the last feeding of altrenogest. Corn oil or estradiol (2 micrograms/kg body weight), 5 ml of charcoal-extracted porcine serum (pS) or pFF were injected im four times at 8-h intervals and gilts were sacrificed 24 or 96 h after last feeding of altrenogest. In Exp. 2, gilts received one of four treatments consisting of 1) pS, injected iv nine times at 8-h intervals starting 48 h before the last feeding of altrenogest; 2) pFF, with injection protocol the same as for pS; 3) estradiol injected im three times and 4) four times at 8-h intervals starting 0 and 24 h, respectively, before the last feeding of altrenogest. Compared with pS or corn oil, estradiol increased (P less than .001) plasma estrogen and decreased (P less than .05) plasma luteinizing hormone (LH) without a significant effect on plasma follicle stimulating hormone (FSH). Estradiol, compared with corn oil, decreased (P less than .01) the number of medium follicles from 24.8 to 0/gilt and decreased (P less than .05) the weight of ovarian follicular fluid from 4.2 to 2.1 g/gilt at 72 h after the first injection. Five milliliters of pFF had no significant effect on plasma gonadotropins or number of medium follicles. However, 20 ml of pFF, compared with pS, decreased (P less than .05) plasma FSH from 45 ng/ml to 9 ng/ml 32 h after the first injection, had no effect on plasma LH, decreased (P less than .01) the number of medium follicles from 29.2 to 2.2/gilt and decreased (P less than .01) follicular fluid weight from 3.9 to 1.6 g/gilt by 72 h after the first injection. These results indicate that estradiol or a non-steroidal component of follicular origin can decrease secretion of gonadotropins and suppress recruitment of medium follicles in the pig.  相似文献   

19.
An attempt was made to induce precocious puberty in gilts approximately 164 days of age by stimulating a luteinizing hormone (LH) secretory pattern similar to that which occurs before normal onset of puberty. Hourly iv administration of 1 μg synthetic gonadotropin releasing hormone (GnRH) for 7 or 8 days resulted in a mean serum LH concentration of 1.7 ± .3 ng/ml in three treated gilts compared with .9 ± .1 ng/ml in three control gilts (P<.08). Serum LH peak frequency was also greater (P<.05) in treated (3.4 ± .5 peaks/4 hr) than in control gilts (1.2 ± .1 peaks/4 hr), but serum LH peak amplitude was not altered (P>.33) by GnRH treatment. All treated gilts displayed estrus and ovulated within 6 days after treatment began, and all control gilts remained prepuberal throughout the study (P=.05). Only one of the three treated gilts displayed a normal estrous cycle and reovulated after treatment. Precocious ovulation but not puberty was induced in gilts by hourly administration of 1 μg synthetic GnRH, indicating that the pituitary and ovaries of 164-day-old gilts are competent and that final sexual maturation occurs at the hypothalamic level.  相似文献   

20.
Ovarian response of collared peccaries (Pecari tajacu), after hormonal stimulation with gonadotropin association (eCG/hCG), was accessed by both gene expression and follicular development. Thus, collared peccaries (n = 8) were treated with the dose used for sows (swine dose, SWD) or with dose adjusted for peccary's weight (allometric dose, ALD). The gene expression of receptors was evaluated for both gonadotropins (FSHR and LHCGR) and growth factors (proteins codified by TGFβR-1, BMPR1-A and BMPR2 genes) in antral follicles, cortex and corpora haemorrhagica (CH). Five days after gonadotropin injection, all females presented CH. The ovulation rate was similar (p > .05) between SWD (4.00 ± 1.17) and ALD (2.50 ± 0.43) group. The total number of follicles per animal and amounts of small (<3 mm), medium (3–5 mm) and large (>5 mm) follicles was similar among groups. However, SWD produced large follicles heavier than ALD group, as accessed by weight of follicular wall biopsies. Ovarian follicles expressed both gonadotropin and growth factor receptors at levels which are independent from gonadotropin dose. In conclusion, the two gonadotropin doses (SWD and ALD) can be used for ovarian stimulation of collared peccary. Additionally, FSH and growth factors (TGFβR-1, BMPR1-A and BMPR2) receptors are more expressed in the early follicle development, while LH receptor seems to be more important in the final of follicular growth.  相似文献   

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