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1.
Administration of hormones to synchronize oestrus is a useful tool in animal breeding. However, exogenous ovarian stimulation may be detrimental to reproductive function. This study was aimed to examine whether an oestrus synchronization with PGF2α/eCG/hCG could affect luteal P4 synthesis in early pregnant gilts. Corpora lutea (CLs) were collected on days 9, 12 and 16 of pregnancy from gilts with natural (n = 16) and synchronized (n = 18) oestrus and analysed for (i) the expre‐ssion of steroidogenic acute regulatory protein (StAR), cytochrome P450 family 11 subfamily A polypeptide (CYP11A1), and 3β‐hydroxysteroid dehydrogenase (3βHSD); (ii) the concentration of P4 in the luteal tissue and blood; and (iii) the expression of luteinizing hormone receptors (LHR) and oestrogen receptors (ERα and ERβ). Additionally, the effect of LH on P4 secretion from CL slices collected from synchronized and naturally ovulated animals has been studied in vitro. PGF2α/eCG/hCG administration increased mRNA expression of StAR, CYP11A1, 3βHSD, and LHR on day 9 and CYP11A1 and LHR on day 12 of pregnancy compared with the control group (p < 0.05). CYP11A1, 3βHSD, LHR, ERα and ERβ proteins were not affected by synchronization; only StAR protein increased in hormonally treated animals (p = 0.017). The concentration of P4 in luteal tissue was greater on day 9 (p < 0.01), but lower on day 16 (p < 0.05) in gilts with hormonally induced oestrus compared with control animals. Blood serum levels of P4 were lower in synchronized than control gilts (p < 0.001). Synchronization did not affect LH‐stimulated P4 secretion from luteal slices; however, greater basal concentration of P4 in incubation medium was detected for CLs collected from synchronized than control gilts (p < 0.05). In conclusion, synchronization of oestrus with PGF2α/eCG/hCG protocol in gilts did not impair the expression of luteal P4 synthesis system, although decreased P4 concentration in the blood.  相似文献   

2.
We investigated whether the limited access to androgens during late prenatal period alters expression of steroidogenic enzymes involved in androgen production: 3β‐hydroxysteroid dehydrogenase/Δ5‐Δ4 isomerase (3β‐HSD), cytochrome P450 17α‐hydroxylase/17,20‐lyase (CYP17) and 17β‐hydroxysteroid dehydrogenase type 1 (17β‐HSD1) or type 3 (17β‐HSD3) in the foetal porcine gonads. Pregnant gilts were injected with anti‐androgen flutamide (for seven days, 50 mg/day/kg bw) or corn oil (control) starting at 83 (GD90) or 101 (GD108) gestational day. To assess 3β‐HSD, CYP17 and 17β‐HSD1 or 17β‐HSD3 expression, real‐time PCR and immunohistochemistry were performed. In testes from flutamide‐treated foetuses, increased 3β‐HSD and CYP17 mRNA expression was observed in the GD90 group, while decreased 3β‐HSD and 17β‐HSD3 mRNA expression and increased CYP17 mRNA expression were found in the GD108 group. CYP17 and 17β‐HSD3 were localized in Leydig cells. Following flutamide administration, the intensity of CYP17 immunostaining was higher in both treated groups, while 17β‐HSD3 intensity was lower in the GD108 group. In ovaries from flutamide‐treated foetuses in the GD90 group, mRNA level for 3β‐HSD was elevated, but it was diminished for CYP17 and 17β‐HSD1. In the GD108 group, flutamide treatment led to lower mRNA level for 3β‐HSD but higher for CYP17. 3β‐HSD was found in granulosa cells, while CYP17 was localized within egg nests and oocytes of forming follicles. Following flutamide treatment, the intensity of 3β‐HSD and CYP17 immunostaining was higher in the GD90 and GD108 groups, respectively. Immunohistochemical staining for 3β‐HSD was restricted to the ovary. Concluding, diminished androgen action in the porcine foetal gonads during late gestation induces changes in steroidogenic enzymes expression, which may led to changes in gonadal function. However, it seems that androgens exert diverse biological effects depending on the gestational period.  相似文献   

3.
In vitro studies were performed to assess whether stimulatory effects of triiodothyronine (T3) on progesterone (P4) production in a granulosa layer (GL) of chicken preovulatory follicles are associated with 3′,5′-cyclic adenosine monophosphate (cAMP) synthesis and mRNA expression of STAR protein, CYP11A1, and HSD3B. Effects of 3,5-diiodothyronine (3,5-T2) on steroidogenic function in these follicles were also investigated. The GL of F3 to F1 follicles was incubated in medium supplemented with T3 or 3,5-T2, LH, or forskolin (F), and a combination of each iodothyronine with LH or F. Levels of P4 and cAMP in culture media were determined by RIA. Expression of genes involved in P4 synthesis (ie, STAR protein, CYP11A1, and HSD3B) in the GL of F3 to F1 follicles incubated in medium with T3 or 3,5-T2 and their combination with LH was performed by real-time PCR. Triiodothyronine increased basal and LH- and F-stimulated P4 secretion by preovulatory follicles. The 3,5-T2 elevated P4 synthesis by F3, had no effect on F2 follicles, and diminished P4 production by the GL of F1 follicles. It had no effect on LH-stimulated P4 production; however, it augmented F-stimulated P4 production by F2 and F1 follicles. Although T3 did not affect basal and F-stimulated cAMP synthesis by the GL of preovulatory follicles, it increased LH-stimulated synthesis of this nucleotide. However, 3,5-T2 elevated F-stimulated cAMP synthesis in F3 and F2 follicles; it did not change basal and LH-stimulated cAMP production. Triiodothyronine decreased basal STAR and CYP11A1 mRNAs in F3 follicles, increased them in F1 follicles, and elevated HSD3B mRNA levels in F1 follicles. Triiodothyronine augmented LH-stimulated STAR, CYP11A1, and HSD3B mRNA levels in F2 and CYP11A1 in F1 follicles. However, T3 decreased LH-stimulated STAR and HSD3B mRNA levels in F1 follicles. The 3,5-T2 did not affect basal STAR and CYP11A1 mRNA expression in all investigated follicles; however, it decreased LH-stimulated STAR expression in F2 and F1 ones. The effects of 3,5-T2 caused elevated basal but diminished LH-stimulated HSD3B mRNA levels. In conclusion, data indicate that both iodothyronines are involved in P4 production in the GL of chicken preovulatory follicles acting alone and additively with LH. Effects of iodothyronines depend on follicle maturation and are associated with modulation of cAMP synthesis and STAR, CYP11A1, and HSD3B mRNA expression. We suggest that iodothyronines participate in maturation and ovulation of chicken follicles.  相似文献   

4.
Canine inflammatory mammary cancer (IMC) has been proposed as a model for the study of human inflammatory breast cancer (IBC). The aims of this study were to compare the immunohistochemical expression of aromatase (Arom) and several hormone receptors [estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor (PR) and androgen receptor (AR)], in 21 IMC cases vs 19 non‐IMC; and to study the possible effect of letrozole on canine IMC and human inflammatory breast cancer (IBC) in vitro using IPC‐366 and SUM‐149 cell lines. Significant elevations of the means of Arom Total Score (TS), ERβ TS and PR TS were found in the IMC group (p = 0.025, p = 0.038 and p = 0.037, respectively). Secondary IMC tumours expressed higher levels of Arom than primary IMC (p = 0.029). Non‐IMC PR‐ tumours contained higher levels of Arom than non‐IMC PR+ tumours (p = 0.007). After the addition of letrozole, the number of IMC and IBC cells dropped drastically. The overexpression of Arom found and the results obtained in vitro further support canine IMC as a model for the study of IBC and future approaches to the treatment of dogs with mammary cancer, and especially IMC, using Arom inhibitors.  相似文献   

5.
Investigations using sustained-release deslorelin implants at various insertion sites have shown that this method consistently induces oestrus in anoestus bitches. However, fertility comparisons between implant insertion sites have not been performed. Anestrous beagle bitches received one 2.1 mg deslorelin implant beneath the vestibular mucosa (VM group; n = 6) or in the subcutaneous tissue between the shoulder blades (SubQ group; n = 8). Vestibular implants were removed when serum progesterone concentrations first exceeded 1.5 ng/ml. Vaginal cytologies and blood samples were collected daily and bitches were inseminated during oestrus. Serum progesterone and deslorelin concentrations were measured and pregnancy status was determined using ultrasonography. There were no differences between groups in the intervals between implant administration and the onset of proestrus, the time of the luteinizing hormone surge and the onset of cytologic diestrus. There were also no differences in the number of corpora lutea or foetuses. However, conception rate was significantly lower in the SubQ group. The pregnancy rate did not differ significantly between the VM and SubQ groups [4 out of 6 (66.7%) and 3 out of 8 (37.5%), respectively]. One bitch (16.7%) in the VM group and three bitches (37.5%) in the SubQ group suffered distinct, premature declines in serum progesterone concentrations starting 1–4 weeks after cytologic diestrus. Serum progesterone concentrations did not recover (premature luteal failure), resulting in abortion. Bitches with premature luteal failure in the SubQ group still had serum deslorelin concentrations >100 pg/ml 20 days after implant insertion, suggesting a possible association between prolonged deslorelin release and luteal failure.  相似文献   

6.
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7.
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8.
Prostaglandin (PG) signalling is involved in human and animal cancer development. PG E2 (PGE2) tumour‐promoting activity has been confirmed and its production is controlled by Cyclooxygenase‐2 (COX‐2) and microsomal PGE synthase‐1 (mPGES‐1). Evidence suggests that mPGES‐1 and COX‐2 contribute to carcinogenesis through the EP2 receptor. The aim of our study was to detect by immunohistochemistry COX‐2, mPGES‐1 and EP2 receptor expression in canine (n = 46) and feline (n = 50) mammary tumours and in mammary non‐neoplastic tissues. COX‐2 positivity was observed in 83% canine and 81% feline mammary carcinomas, mPGES‐1 in 75% canine and 66% feline mammary carcinomas and the EP2 receptor expression was observed in 89% canine and 54% feline carcinomas. The frequency of COX‐2, EP2 receptor and mPGES‐1 expression was significantly higher in carcinomas than in non‐neoplastic tissues and adenomas. COX‐2, mPGES‐1 and EP2 receptor expression was strongly associated. These findings support a role of the COX‐2/PGE2 pathway in the pathogenesis of these tumours.  相似文献   

9.
The absence of fertility problems in male dogs after a single treatment with deslorelin acetate (Suprelorin®) is well acknowledged. However, reports on the application of deslorelin in the bitch and information concerning fertility after implant treatment are still limited. In this retrospective study, data concerning induced and spontaneous oestruses of 39 bitches from 17 breeds, treated with deslorelin acetate implants (4.7 mg Suprelorin®, Virbac, France), were retrieved to assess post‐treatment fertility (ovulation rate, pregnancy rate and litter size). Animals were grouped according to treatment characteristics: group 1 (Gr1) – females submitted to oestrus induction, showing natural oestruses afterwards (n = 19); group 2 (Gr2) – females re‐implanted with 4.7 mg deslorelin acetate to re‐induce oestrus, showing subsequent spontaneous post‐implant oestruses (n = 7); and group 3 (Gr3) – females submitted to a 4.7 mg deslorelin acetate implant for oestrus suppression, evaluated at subsequent spontaneous post‐implant oestruses (n = 13). Comparison of fertility traits between induced and post‐treatment spontaneous oestruses in Gr1 and Gr2 (short treatments), or between spontaneous oestruses after long‐treatment schedules (Gr 3) revealed a slightly better performance in spontaneous cycles compared with induced cycles: ovulation rate post‐treatment was 97.1%, 94.1% and 94.4% and the pregnancy rate post‐treatment was 91.2%, 88.9% and 84.6% for groups 1, 2 and 3, respectively. Nevertheless, fertility in induced and post‐treatment oestruses was considered normal. Moreover, the individual litter size did not differ within groups between induced and spontaneous cycles. From these findings, we concluded that treatment with 4.7 mg deslorelin implants did not compromise the bitches' fertility in subsequent oestruses.  相似文献   

10.
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11.
Testosterone secretion and the expression and relative contents of steroidogenic acute regulatory (StAR) protein and steroidogenic enzymes cholesterol side-chain cleavage cytochrome P450 (P450scc), 3β-hydroxysteroid dehydrogenase /Δ5 → Δ4 − isomerase (3β-HSD), and 17α-hydroxylase cytochrome P450/C17–20 lyase (P45017α) were determined in testicular tissues of bulls treated with a LHRH agonist. Testis morphology and spermatogenesis were also examined. In Experiment 1, bulls (30-mo-old) received no treatment (control, n = 7) or were implanted for 10 days with the LHRH agonist deslorelin (n = 7). Bulls were castrated on Day 10 and testis tissues prepared for Western and Northern blotting. At castration, bulls implanted with deslorelin had greater plasma testosterone (5-fold) and testis content of testosterone (10-fold) compared with control bulls. Relative content (per μg total testis protein or RNA) of StAR protein, 3β-HSD, P450scc, and mRNA for P45017α in bulls treated with deslorelin ranged from 3- to 6-fold that of control bulls. In Experiment 2, bulls (20-mo-old) were left untreated (control, n = 6) or implanted with deslorelin (n = 12) for 120 days. On Day 120, bulls were castrated and right testis tissues prepared for morphology. Testis volume and weight were increased (P < 0.01) in bulls treated with deslorelin compared with control bulls. Stereological analysis revealed that this increase occurred in all compartments (seminiferous epithelium, lumen and interstitium) studied, but was significant (P < 0.01) only for the seminiferous epithelium. Absolute numbers of round spermatids per testis were increased (P < 0.05) in bulls treated with deslorelin compared with control bulls. Increased testosterone secretion in bulls treated with deslorelin was associated with increased testicular StAR protein and steroidogenic enzymes. Bulls treated long-term with deslorelin had a faster rate of testis growth and increased daily sperm production at the end of the experiment.  相似文献   

12.
Spontaneous invasive non‐inflammatory canine mammary carcinomas (CMC) and their regional lymph nodes (LN) were analysed (n = 136). Histological grade (HG) and vascular invasion (VI) in the tumours and lymph node status were recorded. Proliferation index (PI), microvessel density (MVD) and vascular endothelial growth factor receptor 2 (VEGFR2) expression were estimated using anti‐proliferating cell nuclear antigen (PCNA), anti‐von Willebrand factor and anti‐Flk‐1, respectively. Eighteen months follow‐up was performed (34 bitches). Tumours of different grades showed differences regarding PI, Flk‐1/integrated optical density (Flk‐1/IOD) and MVD. Every feature showed significant association with LN status through bivariate analyses. From multivariate analyses, VI and Flk‐1/IOD were selected to predict LN status. Data revealed that the probability of a CMC‐bearing bitch to remain alive at 1, 4, 5 and 14–18 months was 0.91, 0.87, 0.81 and 0.77, respectively. Besides LN status, VI was the only feature positively correlated with survival time, although a trend to shorter survival of animal patients bearing high expressing VEGFR2 CMC was noted.  相似文献   

13.
This study was conducted to evaluate clinical efficacy of deslorelin for inhibiting reproduction in the bitch. Ten adult healthy bitches or bitches with mammary neoplasia for which owners were requesting suppression of cyclicity without performing gonadectomy were administered a 4.7- or a 9.4-mg deslorelin implant subcutaneously. The first implant of deslorelin was administered in anoestrus (n = 5) or in dioestrus (n = 5). Treatment was repeated every 5 months for as long as necessary based on the clinical situation of the dog and owner's desires. Some of the bitches implanted in anoestrus came in heat within 4–15 days after treatment, while none of the bitches implanted in dioestrus showed heat during treatment. Suppression of reproductive cyclicity was successfully achieved in 6/10 bitches for 1–4 years. No behavioural and local/general side-effects were observed in any of the treated bitches. The 4.7-mg deslorelin implant may work well for suppression of cyclicity provided that it is administered in dioestrus and at intervals of 4.5 months. A 9.4-mg implant may be more suitable for this use although its efficacy may also be shorter than 12 months. Owner compliance is an important limiting factor.  相似文献   

14.
In ruminants, superovulatory treatments started at the time of follicular wave emergence result in greater and less variable ovulatory responses and embryo yields compared with the treatments begun in the presence of a large growing antral follicle(s) from the previous waves. The progesterone–oestradiol treatment is routinely used for follicular wave synchronization in cattle. The main objective of this study was to characterize the ovarian responses, hormonal profiles and in vivo embryo production in anoestrous Rideau Arcott ewes (May‐June), which were superovulated after pretreatment with medroxyprogesterone acetate (MAP)‐releasing intravaginal sponges and a single dose of oestradiol‐17β (E2‐17β). Six days after insertion of MAP sponges, eight ewes were given an i.m. injection of 350 μg of E2‐17β (E2‐17β‐treated ewes); 10 ewes were given an i.m. injection of vehicle (control ewes). Multiple‐dose Folltropin®‐V treatment, followed by the bolus injection of GnRH (50 μg i.m.), began 6 days after E2‐17β/vehicle injection. Transrectal ovarian ultrasonography revealed that: (i) the interval between E2‐17β/vehicle injection and regression of all follicles ≥5 to 3 mm in diameter was shorter (p < 0.01; 2.6 ± 0.4 vs 4.8 ± 0.6 days respectively); and (ii) the interval between injection and emergence of the next follicular wave was longer (p < 0.05; 5.4 ± 0.3 vs 1.2 ± 0.4 days, respectively) in E2‐17β‐treated than in control ewes. During the 6 days after injection, the mean FSH peak concentration and basal FSH concentration were lower (p < 0.01) in E2‐17β‐treated ewes. The mean ovulation rate and the number of recovered embryos did not differ (p > 0.05) between the two groups of ewes. However, the number of luteinized unovulated follicles per ewe, and the variability in the number of luteal structures and overall embryo yield were less (p < 0.05) in E2‐17β‐treated compared with control ewes. In conclusion, the MAP–E2‐17β pretreatment significantly reduced the variability in ovarian responses and embryo yields, without affecting the embryo production in superovulated anoestrous ewes.  相似文献   

15.
The exact cause of steatosis, one of defects in Japanese beef carcasses, has not been elucidated to date, because it is very difficult to diagnose cyclopedically with certain reproducibility due to the bias in the outbreak. Therefore, the objective of this study was to assess the influence of polymorphisms in retinol dehydrogenase 16 (RDH16), myoferlin (MYOF) and vascular endothelial growth factor receptors 1 and 2 (VEGFR1, VEGFR2) on carcass‐graded Musculus trapezius steatosis. For logistic regression analysis, 646 carcasses shipped from 29 farms in Miyazaki, Japan, were used. The GG genotype in RDH16 showed significant odds ratios against AA and AG. In VEGFR1, CT had a significant odds ratio against CC. After evaluating for interaction, highly significant odds ratios were observed in the combinations that included the GG risk genotype in RDH16. It is noteworthy that there was no steatosis in the combination GG (RDH16) and CC (VEGFR1). It may be concluded that there is a possibility that steatosis can be suppressed by the CC genotype in VEGFR1. The current study revealed the influence of genetic polymorphisms on M. trapezius steatosis that had not been reported until now, and may help elucidate the cause of steatosis.  相似文献   

16.
This study examined the morphology and immunohistochemical features of the prostate gland in 15 captive‐reared male greater cane rat of known reproductive and medical history. Samples of the glands were taken after gross examination and routinely prepared for both histological and ultrastructural analysis. Immunohistochemistry was also carried out on paraffin‐embedded sections of the glands using rabbit polyclonal antibodies against oestrogen receptors (ERα and ERβ) and mouse monoclonal antibody for the progesterone receptor (PR). The prostate, which constitutes 0.04% of the body weight, was a paired, lobulated, brownish gland having three left and four right lobes that partly cover the pelvic urethra. Based on the amount and arrangement of the secretory epithelial folding and relative to their distances to the urethra, two histological zones, the central and peripheral, were identified. However, the epithelium of both zones was lined by predominantly simple cuboidal cells with occasional basal cells. The main ultrastructural features of these cuboidal cells were the presence of several nuclear pores on the nucleus, moderately well‐developed, short microvilli and bleb‐like apical projections, as well as inter‐cellular lacunae seen between these cells and the basal cells. The cuboidal epithelial cells also showed positive nuclear staining for ERα and ERβ but not for PR. It is however interesting that the ERα‐positive staining was more at the epithelial cells, which is uncommon. These findings highlight the peculiarities in the structure and ultrastructure as well as the unique expression of the oestrogen receptors in the prostate gland of the greater cane rat.  相似文献   

17.
Cystic ovarian disease (COD) is an important cause of infertility in cattle, and ACTH has been involved in regulatory mechanisms related to ovarian function associated with ovulation, steroidogenesis, and luteal function. Here, we examined the localization of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) and 11βHSD2 proteins in the ovary of healthy cows and animals with spontaneous and ACTH-induced COD and the in vitro response of the follicular wall exposed to ACTH. After stimulation by ACTH, we documented changes in 11βHSD expression and cortisol secretion by the follicular wall of large antral and follicular cysts. Follicular cysts showed a higher constitutive expression of both enzymes, whereas ACTH induced an increase in 11βHSD1 in tertiary follicles and follicular cysts and a decrease in 11βHSD2 in follicular cysts. Moderate expression of 11βHSD1 was observed by immunohistochemistry in granulosa of control animals, with an increase (P < 0.05) from primary to secondary, tertiary, and atretic follicles. The level of immunostaining in theca interna was lower than that in granulosa. The expression of 11βHSD2 was lower in the granulosa of primary follicles than in that of secondary, tertiary, and atretic follicles and was lower in the theca interna than in the granulosa. In ACTH-induced and spontaneously occurring follicular cysts, differences from controls were observed only in the expression of 11βHSD1 in the granulosa, being higher (P < 0.05) than in tertiary follicles. These findings indicate that follicular cysts may be exposed to high local concentrations of active glucocorticoids and indicate a local role for cortisol in COD pathogenesis and in regulatory mechanisms of ovarian function.  相似文献   

18.
The aim of the present study was to evaluate the expression and localization of lymphangiogenic factors (VEGF-C and VEGF-D), their receptor (VEGFR3) and lymphatic endothelial marker (LYVE1) in buffalo placenta during early pregnancy [EP], and to investigate the functional role of lymphangiogenic growth factors in placental lymphangiogenesis. The mRNA and protein expression of VEGF-C, VEGF-D, their receptor VEGFR3 and LYVE1 showed significant expression in EP1 (29–42 days) and EP2 stages (51–82 days) both in caruncle (maternal part) and cotyledon (foetal part) of the buffalo placenta. Immunoreactivity of VEGF-C, VEGF-D and LYVE1 was observed around the endometrial gland, in lymphatics and trophoblast cells, whereas VEGFR3 mainly localized in lymphatics of the caruncle and cotyledons. Cultured trophoblast cells were treated with VEGF-C/VEGF-D (50, 100 and 150 ng/ml) and combined doses of VEGF-C and VEGF-D (150 ng/ml) each for different time durations (24, 48 and 72 h). The mRNA expression of LYVE1 and PCNA was significantly (p < .001) upregulated with VEGF-C and VEGF-D and combined treatment (@150 ng/ml), as well as significantly downregulating Caspase-3 at 48 and 72 h. Thus, the present study provides evidence that lymphangiogenic factors are expressed in buffalo placental compartments and they may play a significant role in the regulation of placental function in water buffaloes.  相似文献   

19.
Deslorelin acetate is a GnRH agonist used for contraception in dogs. This study aimed to evaluate the treatment of pre‐pubertal female dogs with deslorelin acetate implants, to better investigate the primary stimulatory effect of the drug and the long‐term effects on the genital tract, throughout repeated treatments. Sicilian hound female dogs (24) were randomly assigned to treated group, control group 1 and control group 2. First group bitches were implanted at 4.5, 9.0 and 13.5 months and monitored clinically, ultrasonographically and endocrinologically, throughout the study period (13.5 months). Control group 1 bitches were not implanted and clinically monitored for the same period. At 18 months, the animals underwent ovariohysterectomy, thus allowing evaluation of the internal genitalia. Control group 2 bitches were ovariohysterectomized at the age of 4.5 months. The suppression of oestrus was obtained in the treated group despite the fact that the first implant caused a modest increase in plasmatic levels of 17‐beta estradiol and an evident cornification of the vaginal mucosa cells (50–80%). Estradiol and progesterone were at baseline levels for the remaining study period, in which no other oestrous manifestations were observed. The external genitalia maintained a juvenile appearance. The ovaries, ultrasonographically, showed no follicular structures and stayed the same size. At 18 months, the genital tract was still juvenile with inactive small ovaries and a thin filiform uterus. Deslorelin suppressed ovarian activity in pre‐pubertal bitches, and oestrous induction was not observed despite the presence of the primary stimulatory effect of the drug. Juvenile genitalia were an expected side effect of the treatment.  相似文献   

20.
Anterior pituitary gland contents of LH and LHß- and α-subunit mRNAs, and circulating concentrations of LH and testosterone, were determined in bulls treated with the LH-releasing hormone (LHRH) agonist deslorelin. Brahman (Bos indicus) bulls (14-month-old) were allocated to two groups and received the following: Control (n = 5), no treatment; Deslorelin (n = 4), four deslorelin implants (approximately 200 μg total deslorelin/day) for 36 d. Plasma concentrations of LH were higher in bulls treated with deslorelin on Day 1, had returned to typical levels by Day 8, and did not differ for control bulls and bulls treated with deslorelin from Day 8 to Day 29. Pituitary content of LH on Day 36 was reduced (P < 0.001) in bulls treated with deslorelin (33 ± 4 ng/mg) compared with control bulls (553 ± 142 ng/mg). Relative pituitary content of LHß-subunit mRNA was also reduced on Day 36 in bulls treated with deslorelin (Control, 0.65 ± 0.10; Deslorelin, 0.22 ± 0.04; P = 0.003). However, α-subunit mRNA relative content did not differ (Control, 0.73 ± 0.15; Deslorelin, 1.06 ± 0.12; P > 0.05). Plasma concentrations of testosterone were increased over the period of the experiment in the bulls treated with deslorelin compared with control bulls. This is the first demonstration of reduced pituitary content of LHß-subunit mRNA and LH, and unaltered content of α-subunit mRNA, in bulls treated with LHRH agonist. This was associated with apparently typical plasma concentrations of LH and elevated plasma testosterone. The anterior pituitary in bulls treated with LHRH agonist, therefore, undergoes classical desensitization and downregulation, but plasma LH and testosterone are not suppressed.  相似文献   

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