Inhibin-like activity in ovarian venous serum after unilateral ovariectomy in prepubertal gilts

To examine a role for inhibin in compensatory ovarian hypertrophy after unilateral ovariectomy (ULO) of prepubertal gilts, changes in inhibin activity in ovarian venous blood were estimated by bioassay. Three groups of 130-day-old gilts were unilaterally ovariectomized after collecting blood from an ipsilateral ovarian vein (Day O); blood samples were obtained from the remaining ovary on Day 2, 4, or 8. Coetaneous gilts underwent sham ovariectomy on Day 0, and venous blood was collected from both ovaries on Day 2, 4, or 8. An assay for inhibin activity, which measured inhibition of secretion of follicle-stimulating hormone (rFSH) by rat pituitary cells in culture, was validated for serum samples. Presumptive inhibin activity was always greater in ovarian venous serum than in peripheral serum samples. In the ULO groups, inhibin activity (in terms of a house reference preparation) in ovarian venous serum was 55 +/- 13 micrograms/ml (means +/- SE, n = 13) on Day 0, 251 +/- 79 (n = 5) on Day 2, 275 +/- 111 (n = 4) on Day 4, and 68 +/- 14 micrograms/ml (n = 4) on Day 8. The five-fold increases on Days 2 and 4 were significant (p less than 0.05). In contrast, no significant differences in inhibin activity were detected between ovarian venous serum (within gilts) or between Days 2, 4, and 8: 82 +/- 29, 73 +/- 30, and 99 +/- 48 micrograms/ml (n=4/day) in control groups. These results demonstrate that, in prepubertal gilts, the remaining ovary's response to ULO includes a major increase in release of inhibin-like activity.     

Alterations in gonadotropin secretion and ovarian function in prepubertal gilts by elevated environmental temperature

The effect of chronic exposure to elevated environmental temperature on gonadotropin secretion and ovarian function was studied in prepubertal gilts. Gilts were maintained under control (15.6 degrees C) or elevated temperature (33.3 degrees C) conditions from 150 to 180 days of age. Endocrine and ovarian responses to bilateral (BLO), unilateral (ULO), and sham ovariectomy were evaluated between 175 and 180 days of age. During the 96-h sampling period after BLO, plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were suppressed in heat-stressed females. Similarly, elevated temperatures abolished the transient rise in FSH and subsequent follicular growth normally associated with ULO. In contrast, environmental treatment had no effect on the secretion of FSH and LH after sham ovariectomy, yet the number of small follicles was lower in gilts exposed to elevated temperatures than in females maintained under control conditions. These results indicate that a chronic exposure to elevated environmental temperature during pubertal development diminished the ability of the hypothalamo-hypophyseal axis to secrete FSH and LH, which had physiological consequences on follicular growth. When provided an appropriate stimulus (ULO), an acute period of FSH secretion and subsequent development of follicles failed to occur in females exposed to elevated temperatures. Consequently, we propose that delayed puberty in gilts during periods of elevated environmental temperatures is due, in part, to a diminished capacity for gonadotropin secretion.     

Effect of prior FSH treatment on the estrus and ovulation responses to eCG in prepubertal gilts

The objective of this study was to determine the effect of pre-treatment of prepubertal gilts with FSH on the estrus and ovulatory responses to eCG injection at two ages. A total of 149 prepubertal Hypor gilts were selected at 150 days (n=76) or 180 days (n=73) of age and assigned to injection of 400 IU eCG plus 200 IU hCG (PG600), 600IU eCG alone (Folligon), pre-treatment with 72 mg FSH (Folltropin) administered as 6 x 12 mg injections at 12 h intervals with 600 IU Folligon 12h after last FSH injection, or non-injected controls. To facilitate detection of estrus, gilts were exposed to a mature boar for 15 min daily for 7 days. To determine ovulatory responses, blood samples were obtained on the day of injection and 10 days later and assayed for progesterone content. Following treatment at 150 days, one control gilt (5.3%) was deemed estrus but ovulation did not occur. Compared to treatment with Folligon alone, PG600 injection tended (P=0.1) to increase the estrus response (52.6% compared with. 26.3%) and increased (P<0.01) the ovulatory response (89.5% compared with. 47.4%). The estrous response in gilts pretreated with Folltropin was intermediate (42.1%) but the ovulatory response (47.4%) was the same as for Folligon alone. Following treatment at 180 days, two control gilts (10.5%) were deemed estrus and ovulation did occur in these gilts. There was no difference between hormone-treated groups for estrus or ovulatory responses, although the ovulatory response of PG600-treated gilts tended (P=0.1) to be greater than for the Folligon-treated group (89.5% compared with 66.7%), with Folltropin-pretreated gilts being intermediate (76.5%). These data demonstrate that the estrus and ovulatory responses of gilts were greater for PG600 than for Folligon and that while responses to PG600 were not affected by gilt age, for the combined Folligon groups, estrous response (P<0.02) and ovulatory response (P<0.05) improved with increased gilt age.     

Uterotropic actions of relaxin in prepubertal gilts

Uterotropic actions of relaxin (RLX) have been demonstrated in rats and mice but not in other species. Experiments were conducted to assess (1) if RLX has uterotropic effects in prepubertal gilts and (2) if RLX-induced imbibition of water by uterine tissues is mediated by histamine. Prepubertal gilts received (i.m.) either 0.5 mg pRLX (greater than or equal to 3000 U/mg; n = 10) in 0.1 M phosphate-buffered saline (PBS) or PBS vehicle (n = 8) every 6 h for 54 h. Additionally, one-half of each group received either (1) the histamine receptor antagonists (300 mg i.m. of each), pyrilamine maleate (H1) and cimetidine (H2), in PBS and corn oil, respectively, or (2) control vehicles every 6 h for 66 h beginning 12 h prior to initiation of RLX treatment. Treatment with RLX stimulated a twofold increase (p less than or equal to 0.05) in uterine weight in prepubertal gilts. Increases in total uterine weight were manifested by greater (p less than or equal to 0.05) uterine water content and dry weight in RLX-treated gilts. Cotreatment with histamine receptor antagonists did not alter RLX-induced changes in uterine water content or dry weight. Uterine contents of soluble protein and DNA were greater (p less than or equal to 0.05) in RLX-treated gilts compared to controls. Treatment with RLX tended (p approximately 0.08) to reduce protein; DNA ratio of uterine tissues and increased (p less than or equal to 0.05) uterine DNA as a percentage of uterine dry weight.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of active immunization against androstenedione on ovarian function in dairy cows and prepubertal gilts

Two experiments were performed to assess the effects of immunization against androstenedione on ovarian function in cows during the first 100 days after calving and in gilts at the onset of puberty.Seven Holstein-Friesian cows were immunized against androstenedione-11α-human serum albumin (AND-HSA) at 3 weeks before and at 3 weekly intervals after calving and compared with ten cows immunized against HSA. Titres against androstenedione were significant but low and variable (1: 280-1: 4). Two cows with the highest titres exhibited abnormal ovarian function which could be attributable to treatment. One cow developed a large follicular cyst and nymphomania. The other cow exhibited mild super ovulation in her first cycle after calving and multiple ovulations during later cycles. Other cows in the AND-HSA group also had a tendency to develop larger than normal follicles and follicular cysts.Groups of twelve prepubertal gilts were immunized against either androstenedione 11α-hemisuccinyl bovine serum albumin (AND-BSA) or BSA at 100, 121 and 142 days of age. Titres against AND were significant but were low and variable (1: 2500-1: 10). There was no effect of immunization against AND on onset of ovulation, puberty or ovulation rate in the first or second ovulatory cycles.     

Formation of ovarian follicular cysts and corpora lutea after treatment with antihistamine or indomethacin in prepubertal gilts

Roles of histamine and prostaglandins in the induction of ovarian cysts after unilateral ovarian manipulation (MAN) and in the process of ovulation were evaluated in prepubertal gilts treated with pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG). Administration of pyrilamine maleate, an H1 receptor antagonist, before MAN or hCG injection reduced the number of cysts formed but did not alter ovulation rate. Administration of cimetidine, an H2 receptor antagonist, failed to alter the incidence, number, or diameters of cysts formed in response to MAN or the ovulation rate on non-MAN ovaries. Administration of indomethacin, an inhibitor of prostaglandin synthesis, before MAN or hCG injection did not alter the incidence, number, or diameters of cysts formed on MAN ovaries but reduced the number of corpora lutea on non-MAN ovaries. Excessive accumulation of fluid in ovarian cysts apparently was mediated by histamine interacting with the H1-type receptor. Enhanced secretion of prostaglandins produced by the cyclooxygenase pathway did not contribute to development of ovarian cysts but, unlike histamine, was required for formation of corpora lutea in prepubertal gilts treated with PMSG and hCG.     

Effect of altering dose of PG600 on reproductive performance responses in prepubertal gilts and weaned sows

This study evaluated the effects of altering dose of PG600 on estrus and ovulation responses in prepubertal gilts and weaned sows. Experiment 1 tested the effects of one (1.0x, 400IU eCG+200IU hCG, n=74), one and a half (1.5x, n=82), or two (2.0x, n=71) doses of PG600 for prepubertal gilts. Estrus (58%) and ovulation (90%) were not affected (P>0.10) by dose. Higher doses increased (P<0.01) numbers of corpora lutea (17, 24, and 25), but not (P>0.10) the proportion of gilts with cysts (26, 36, and 46% for 1.0x, 1.5x, and 2.0x, respectively). Experiment 2 tested the effects of 0x (n=30), 0.5x (n=32), 1.0x (n=29), or 1.5x (n=30) doses of PG600 in weaned sows. Dose did not influence return to estrus (90%, P>0.10). There was an effect of dose (P<0.05) on incidence of cysts (3.4, 1.8, 6.4, and 29.8%, for 0x, 0.5x, 1.0x, and 1.5x doses, respectively). The 0.5x dose increased (P<0.01) farrowing rate (83.2%) compared to 0x (72.1%) and 1.5x (58.6%), but was not different from 1.0x (76.4%). Total pigs born (10.5+/-0.8) did not differ (P>0.10) among treatments. These data suggest that increasing dose of PG600 to 1.5x for gilts increases the number of corpora lutea but does not alter the proportion expressing estrus or ovulating. Reducing dose of PG600 for weaned sows did not alter estrus or ovulation, but the 0.5x dose increased farrowing rate compared to no PG600.     

Effects of gonadotropin treatment on ovarian follicle growth, oocyte quality and in vitro fertilization of oocytes in prepubertal gilts

This study was undertaken to compare the effects of FSH-pituitary (FSH-P), eCG, and a combination of gonadotropins containing 400 IU eCG and 200 IU hCG (PG 600) on the growth of large follicles, oocyte quality and in vitro fertilization (IVF) rate of in vitro matured (IVM) oocytes in prepubertal gilts. The ovaries were removed via midventral laparotomy 48 h (Experiment 1) or 72 h (Experiment 2) after the first injection. In Experiment 1, 30 gilts received 1 of 5 treatments: 1) saline (3 ml i.m., once, n = 6); 2) FSH-P8 (8 mg i.m., twice, with a 24-h interval, n = 6); 3) FSH-P16 (16 mg i.m., twice, with a 24-h interval, n = 6; 4) eCG (1000 IU i.m., once, n = 6); or 5) PG 600 (5 ml i.m., once, n = 6). Compared with saline, treatment with PG 600 or eCG induced significant (P < 0.05) growth of large follicles (> or = 6 mm). In Experiment 2, 16 gilts received 1 of 5 treatments: 1) saline (n = 4); 2) FSH-P8 (n = 4); 3) FSH-P16 (n = 4); 4) eCG (n = 4), or 5) PG 600 (n = 4). The same injection protocol as in Experiment 1 was used. Compared with treatment with FSH-P8 or FSH-P16, eCG increased (P<0.05) the number of large follicles. The proportion of good oocytes was increased (P<0.05) with FSH-P8 or FSH-P16 compared with treatment with eCG or PG 600. Moreover, oocytes from eCG-treated gilts had a greater (P<0.05) rate of male and female pronuclei than FSH-P or saline-treated gilts. In conclusion, treatment with FSH-P resulted in a higher proportion of oocytes with multilayer cumulus cells, whereas treatment with eCG resulted in higher pronuclear rates following in vitro fertilization in prepubertal gilts.     

Serum concentrations of prolactin, oestrogen and LH during the perioestrous period in prepubertal gilts induced to ovulate and mature gilts

The temporal relationships of serum prolactin, oestrogen and LH concentrations during the perioestrous period were compared in prepubertal gilts induced to ovulate by PMSG and hCG and in mature gilts. In Exp. 1, 2 sustained prolactin surges, beginning 4 days and 1 day before the preovulatory LH surge, occurred in all mature gilts. A single preovulatory prolactin surge occurred in 3 prepubertal gilts, starting just before the preovulatory LH surge, but 4 prepubertal gilts had neither a prolactin nor an LH surge. A status (prepubertal or mature) versus time interaction (P less than 0.01) was detected for serum prolactin concentrations. A preovulatory oestrogen surge occurred in all gilts but was of lesser magnitude (P less than 0.01) and duration (P less than 0.05) in the prepubertal gilts without prolactin and LH surges compared to mature gilts and of lesser magnitude (P less than 0.01) compared to prepubertal gilts with prolactin and LH surges. The relative timing of the oestrogen surge in prepubertal gilts corresponded with that of mature gilts when adjusted to the LH surge (if present) but was delayed (P less than 0.01) in all prepubertal gilts if standardized to the hCG injection. In Exp. 2, mature gilts were examined to determine whether 2 perioestrous prolactin surges were characteristic of all cycling gilts. Of 9 gilts, 8 exhibited an initial prolactin surge 4-5 days before oestrus and 5/9 gilts exhibited a periovulatory prolactin surge. The presence of 2 perioestrous serum prolactin surges was not a requirement for subsequent pregnancy maintenance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Opioidergic control of gonadotrophin secretion in the prepubertal gilt during restricted feeding and realimentation

Prepubertal gilts, having undergone a 7-day period of feed restriction to a maintenance ration, were allocated to one of 4 treatments; restricted feeding at 09:00 and 17:00 h for an 8th day both with (Group RN) and without (Group R) administration of the opioid antagonist naloxone hydrochloride (1 mg.kg-1 at 09:30 h followed by 0.5 mg.kg-1 at hourly intervals for 7 h), or feed to appetite with (Group ALN) and without (Group AL) naloxone administration. Gilts were bled at 10-min intervals on Day 8 from morning to evening feed and plasma LH, FSH and prolactin concentrations were measured by radioimmunoassay. Compared with Group R gilts, Group AL gilts exhibited significantly (P less than or equal to 0.05) higher mean and maximum LH concentrations and pulsatility, lower prolactin concentrations (P less than 0.05) but no significant difference in FSH secretion. Naloxone significantly depressed the increase in LH after re-feeding (Group ALN) (P less than 0.05). Once again there were no significant effects on FSH secretion. Naloxone also significantly depressed prolactin secretion in feed-restricted gilts (P less than 0.05). These results confirm that re-feeding of feed-restricted prepubertal gilts stimulates an immediate increase in LH secretion and that this elevation is not mediated via a suppression of inhibitory endogenous opioidergic tone. Rather, naloxone treatment appeared to expose a latent inhibition of LH secretion. The control of LH secretion is distinct from that of FSH in this model.     

Serum concentrations of melatonin in prepubertal or postpubertal gilts exposed to artificial lighting or sunlight

To determine if the type of environmental lighting or reproductive status influences secretory patterns of serum melatonin, gilts were exposed to artificial light or full sunlight during the summer months. In Experiment 1, eight prepubertal and eight postpubertal gilts (Hampshire x Yorkshire x Duroc) were exposed to light intensity of 700 lux in an environmentally controlled room from 0730 to 1900 h daily. An additional eight prepubertal and eight postpubertal gilts were reared outdoors in an open modified-front gestation building and fed on a concrete apron outdoors where light intensity approached 50,000 lux in full sunlight. After 2 mo of acclimating to these environmental conditions, blood samples were drawn from each gilt at 2-h intervals from 1000 to 0200 h. Serum concentrations of melatonin were assayed utilizing Guildhay antisera. The experiment was repeated during the same months of the following year utilizing different gilts (Experiment 2). During both replications, neither light intensity nor reproductive status affected the secretory patterns of melatonin during the sampling period (P >0.05). In both prepubertal and postpubertal gilts, serum concentrations of melatonin were not reduced (P >0.05) by exposure to direct sunlight. Since baseline concentrations of serum melatonin were not reduced by sunlight during the day, the incidence of nocturnal rises of melatonin was not increased (P >0.05) in either prepubertal or postpubertal gilts.     

No single way to explain cytoplasmic maturation of oocytes from prepubertal and cyclic gilts

The objective of this study was to evaluate selected aspects of cytoplasmic maturation in oocytes from prepubertal and cyclic crossbred gilts before and after in vitro maturation. For this purpose, cortical granule redistribution, mitochondrial DNA content and mitochondria translocation were analyzed. Moreover, for the first time the fatty acid profiles in follicular fluid (FF) of both gilt categories was evaluated. The nuclear maturation (the percentage of metaphase II oocytes was 83% in prepubertal gilts compared with 87% in cyclic gilts), cortical granule relocation from the cortex to peripheral ooplasm (98.7% vs. 98.8% of oocytes, respectively) and mitochondrial DNA content (227 543 vs. 206 660, respectively) was not affected by sexual maturity of the donor gilt. However, the redistribution of active mitochondria during in vitro maturation was observed only in the oocytes of cyclic gilts. With regard to FF analysis, saturated, unsaturated, and monounsaturated fatty acids were significantly more abundant in the FF of prepubertal females. In particular, stearic (C18:0) and palmitic (C16:0) fatty acids had significantly higher concentrations in the FF of prepubertal gilts. In conclusion, although the oocytes of prepubertal gilts matured in vitro at a rate similar to those of cyclic gilts, they differed with respect to the selected factors attributed to cytoplasmic maturation. We suggest that the higher content of particular fatty acids, which is known to have a negative influence on oocyte maturation, as well as impaired mitochondria redistribution are factors limiting the maturation potential of oocytes from prepubertal gilts.     

GH and IGF-I binding sites in adipose tissue, liver, skeletal muscle and ovaries of feed-restricted gilts

The influence of feed restriction on GH and IGF-I binding was examined in the cyclic gilt. IGF-1, IGFBPs, insulin and leptin levels in plasma were also measured. Twenty-four gilts whose oestrous cycle was synchronised were used. From day 3 to day 12, (with day 0 being the first day of oestrus) feed allowance was 240% and 80% of the energy requirements for maintenance for well-fed (H) and restricted gilts (L) respectively. Six gilts in each group were treated with an antagonist of GnRH but the treatment had no effect on any reported measurements. Blood and tissue samples were collected on days 12 and 13 respectively. L gilts lost live weight whereas H gilts gained weight. Plasma IGF-I, insulin and leptin concentrations were lower in L than in H gilts whereas plasma IGFBP levels were not affected by feed restriction. The specific binding of 125I-bGH to adipose tissue, liver, skeletal muscle and ovary membranes did not differ significantly between H and L gilts. Specific binding of 125I-IGF-I to hepatic membranes was higher in L than in H gilts whereas it did not differ between the two groups in the other tissue membranes.     

Oestrous and ovarian responses to exogenous progesterone and oestrogen in prepubertal ewe lambs in relation to the fecundity of their dams

Oestrus was consistently induced by 20, 40 or 80 microgram oestradiol benzoate in progesterone-primed lambs aged 23 weeks and 17 weeks respectively in two experiments. The duration of oestrus increased linearly with increasing log dose of oestrogen, and was negatively correlated with the time of its onset. In the absence of progesterone there was a reduced incidence, later onset and shorter duration of oestrus. Progesterone alone did not induce oestrus. In lambs treated during January (Exp. 2), a later date of injection of oestrogen was associated with earlier onset and longer duration of oestrus. The induced oestrus was anovulatory. Oestrogen reduced the proportion of lambs with follicles greater than or equal to 3 mm in diameter whilst progesterone had no effect. Lambs which were the progeny of low- and high-fecundity dams did not differ in their oestrous or ovarian responses. Correlations between the dam's lamb production index and the time to onset and duration of the induced oestrus were also not significant.     

Gonadotrophin secretion and ovarian responses in prepubertal heifers actively immunized against androstenedione and oestradiol-17 beta

Groups of heifer calves received a primary immunization against androstenedione (Group A; N = 11) or oestradiol-17 beta (Group E; N = 10) at 3 months of age and booster injections on 5 occasions at 2- to 3-month intervals. Controls (Group C, N = 11) were immunized against human serum albumin alone using the same protocol. Immunity was achieved against both steroids as judged by the secondary antisteroid antibody titres in Group A (1126 +/- 261; reciprocal of titre) and Group E (10,357 +/- 4067) heifers. In Groups A and E there was a general decline in the respective peak antibody titres after successive booster injections. From 3 to 9 months of age mean plasma concentrations of LH were higher (P less than 0.05) in Group E heifers (0.89 +/- 0.08 ng/ml) than in Group C (0.46 +/- 0.03 ng/ml) and Group A (0.59 +/- 0.05 ng/ml) heifers which did not differ from one another. There were no differences between groups in plasma FSH concentrations. At 10 months of age the LH response to exogenous LHRH was of higher (P less than 0.05) amplitude for heifers in Group E (2.59 +/- 0.56 ng/ml) than for those in Groups C (0.61 +/- 0.07 ng/ml) and A (1.04 +/- 0.22 ng/ml). Elevated plasma progesterone concentrations at 5 months of age were shown by 2 heifers in Group C, 10 in Group A, and 6 in Group E. From 8 to 14 months of age a consistently higher proportion of Group A heifers exhibited elevated progesterone compared with Group C and Group E heifers. After ovarian synchronization and booster injection at 15 months of age a corpus luteum was present in 2 heifers in Group C, 7 in Group A and none in Group E. The ovaries of Group A heifers were different from those of Groups C and E and were characterized by greater numbers of 2-4 mm follicles. It is concluded that active immunization against gonadal steroids influences both LH secretion and ovarian function in prepubertal heifers. Early increases in ovarian activity in androstenedione-immunized heifers are maintained after puberty and may therefore confer some lifetime reproductive advantages.     

Ultrasonographic characterization of the ovaries and the uterus in prepubertal and pubertal gilts

In two experiments (EXP), 44 and 52 crossbred gilts (mean age+/-S.D. and weight+/-S.D.: 204+/-22 and 203+/-9 days, 114+/-13 and 127+/-12 kg, respectively, in EXP 1 and 2) from four farms were examined by means of transcutaneous ultrasonography (US) to define the characteristics of the ovaries and the uterus (echotexture, size) and to investigate the appropriateness of US to determine sexual maturity. Gilts were judged as prepubertal [PRE; follicles 2-5 mm (F2-5) only] or pubertal [PUB; F7-8, corpora lutea (CL), corpora haemorrhagica (CH)] at the first (PUB-1; EXP 1) or a subsequent estrous cycle [PUB-2; additionally corpora albicantia (CA); EXP 1] by US, and results were verified by postmortem examination (EXP 1), or progesterone analysis and detection of estrous signs (EXP 2). Accuracy of US was 100% for PRE and PUB (both EXP) and 77.3% for PUB-1 and PUB-2 (EXP 1). PRE and PUB with CL/CH had uteri of homogeneous, PUB with F7-8 of heterogeneous echotexture. The size was expressed as the mean sectional area (SAsono) of 2-5 cross-sections of the uterine horns (calculated by multiplication of 1/2 the maximum x the minimum dimension of the cross-sections x pi). SAsono corresponded with the sectional area of postmortem dissected transverse uterine segments relatively with r=0.92 (P<0.0001; EXP 1). Mean SAsono (both EXP) and mean uterine weight (EXP 1) were PRE相似文献   

Short-term pituitary-testicular responses of prepubertal ram lambs to hemicastration

To examine the short-term effects of hemicastration on pituitary-gonadal responses, 12 ram lambs were anesthetized and hemicastrated at 4 mo of age and killed (n = 4) at 2 (HC2), 7 (HC7), or 14 (HC14) days following surgery. Four intact (INT) rams were killed 14 days following anesthesia. Testis and pituitary weights were similar between HC and INT rams. Serum follicle-stimulating hormone (FSH) in HC rams increased within 6 h, peaked at 12 h, and remained elevated above INT levels throughout the study. Overall mean serum testosterone levels in HC rams were lower than in INT rams for the first 48 h, but were similar by 3 days post-surgery. Pulsatile luteinizing hormone (LH) and testosterone secretion was suppressed for the first 9.5 h following anesthesia and/or surgery in both HC and INT animals. A single LH pulse and succeeding testosterone pulse occurred in 10/12 HC and 4/4 INT rams between 10 and 14 h post-surgery, both of which were lower in amplitude in HC than INT animals. However, on Day 7, pulsatile secretory patterns of LH and testosterone were similar, suggesting compensatory androgen secretion had occurred in HC rams. Pituitary LH content was unaffected by hemicastration. In contrast, pituitary FSH content was greater in HC7 and HC14 compared to HC2 and INT animals. Pituitary gonadotropin hormone-releasing hormone (GnRH) receptor concentrations were similar in INT, HC7, and HC14 rams, but were slightly reduced in HC2 rams. Neither testicular LH nor FSH receptor concentrations were altered by hemicastration at any time.(ABSTRACT TRUNCATED AT 250 WORDS)     

FSH is superior to eCG for promoting ovarian response in Chinese Bamei gilts

The Bamei gilt is a Chinese native breed located in northwest China, which adapts to the extremely dry and cold environment and is distinguished for its excellent reproductive and maternal characters. To ensure sufficient numbers of embryos for transgenic and nuclear transfer research, hormonal induction of gilt estrus and superovulation may be necessary. The objective of this study was to compare the superovulation effects of equine chorionic gonadotropin (eCG, Group A) and FSH (Groups B-D) in Chinese Bamei gilts. The results show that though eCG could produce more corpora lutea (CL, 14.3) than the control (CL, 9.2), and the FSH treatments had significantly increased the number of CL compared with the eCG treatment. Within the different FSH protocols, the numbers of CL were significantly greater in Groups B (CL, 77.8) and C (CL, 66.8) than in Group D (CL, 42.7), however, ovarian cysts were observed in Groups B and C, but not in Group D. These data suggest that Group D (280 IU FSH) is a suitable protocol to facilitate the development of ovarian follicles and increase the number of useful embryos per gilt for embryos recovery. The optimal FSH protocol of superovulation in Bamei gilts appears to be: D13/100 IU, D14/80 IU, D15/60 IU, D16/40 IU plus prostaglandin (PG) 0.2mg, D17/hCG 1000 IU.     

Resumption of follicle growth in gilts after ovarian autografting

The aims of the study were to evaluate autografting of porcine ovarian tissue in terms of establishment of a blood supply, follicle survival and development, commencement of oestrous cycles and endocrine patterns in this polyovular species. Experiment 1, a preliminary study on four gilts, showed that ovarian tissue slices survived the grafting procedure and re-vascularised. In Experiment 2, a further six pre-pubertal gilts had both ovaries surgically removed and two thin cortical slices of each ovary were immediately reattached to each of the ovarian pedicles. Blood samples were taken at surgery and then weekly. Two gilts were slaughtered 2 weeks after surgery and ovarian tissue recovered. The remaining four gilts underwent daily checks for behavioural oestrus until slaughter 24 weeks after surgery. All four gilts showed standing heat at least once prior to slaughter. Plasma LH and FSH concentrations increased significantly (P<0.01) by 3 days after surgery, then fell gradually, but did not return to pre-surgery levels. Progesterone concentrations showed some evidence of cyclicity in all animals. In the grafted tissue, re-vascularisation of the tissue was apparent by 2 weeks post-grafting, although no preantral or antral follicles were observed. The tissue recovered after 24 weeks contained healthy preantral and antral follicles, luteal tissue and some large cystic follicles. It is unclear whether these cysts were the result of ovarian or hypothalamic/pituitary disturbance. In conclusion, the results of this study have shown that follicle growth and resumption of cyclicity can be achieved following ovarian autografting in pigs and indicate that this will be a useful model for investigating the mechanisms that control the early stages of follicular growth and ultimately ovulation rate in this multiovular species.