Dimeric inhibin concentrations in mares with granulosa-theca cell tumors

OBJECTIVE: To determine whether concentrations of dimeric inhibin (CaCA) are greater in plasma and tumor fluid from mares with granulosa-theca cell tumors (GTCT), compared with concentrations in plasma and equine follicular fluid (eFF) from control mares. ANIMALS: 6 mares with GTCT and 12 clinically normal mares. PROCEDURE: The alphabetaA immunoradiometric assay used 2 antibodies, one against each subunit of inhibin (alpha and betaA subunits). Tumor tissue, tumor fluid, and a single blood sample were collected at the time of surgical removal of the GTCT. A single blood sample was collected from 7 control mares during various stages of the estrous cycle. Five other control mares were ovariectomized when their ovaries contained growing follicles of 25 to 35 mm in diameter. A blood sample and eFF from the largest follicle were collected at the time of ovariectomy. RESULTS: Mares with GTCT had significantly greater plasma concentrations of betabetaA (mean +/- SEM, 0.86 +/- 0.53 ng of recombinant human-alphabetaA/ml), compared with control mares (0.14+/-0.02 ng/ml). Concentrations of alphabetaA in tumor fluid and eFF were similar. Concentrations of alphabetaA were significantly lower after ovariectomy. CONCLUSIONS AND CLINICAL RELEVANCE: Dimeric inhibin concentration was higher in plasma from mares with GTCT than in plasma from control mares. Increased granulosa cell mass and loss of mechanisms regulating alphabetaA release in mares with GTCT likely accounted for the increase in plasma concentrations. Measurement of alphabetaA concentrations may be useful for identifying mares with GTCT.     

Expression of inhibin/activin subunits in the ovaries of fetal and neonatal mice

In the present study, the expression of inhibin/activin subunits in the mouse ovary from 13 days post-coitus (dpc) to 30 days postpartum (dpp) was investigated. Circulating FSH, LH, inhibin A, and inhibin B in neonatal to 30 dpp ovaries were measured. Inhibin/activin subunits (alpha, beta(A), beta(B) ) were weakly stained in 13 dpc ovarian stromal cells and increased with age. Inhibin alpha subunit was immunolocalized in follicular granulosa cells at each developmental stage. In 30 dpp ovaries, several large antral follicles were strongly stained for inhibin alpha subunit. Inhibin beta(A) subunit was weakly immunolocalized in granulosa cells until 20 dpp. Moreover, 2 to 3 antral follicles from 20 to 30 dpp were strongly stained for inhibin beta(A) subunit. There was relatively high immunoactivity for inhibin beta(B) subunit in neonatal to 30 dpp mouse ovaries. All three inhibin subunits were stained in theca-interstitial cells from 15 dpp onward. RIA data showed that a temporal increase in circulating FSH occurred around 10 dpp, while the plasma concentrations of LH were sustained at a relatively higher level from 8 to 15 dpp. Inhibin B was detectable in circulation early at 1 dpp (day of birth), and a clear increase in inhibin B occurred around 8 dpp. Circulating inhibin B gradually increased from 20 dpp to 30 dpp, indicating a negative correlation with FSH. Inhibin A levels were only measured on 25 and 30 dpp, and the levels were low. These results suggest that inhibins play an important role in early folliculogenesis in mice. In addition, inhibin B seems to be the main functional isoform from the neonatal to prepubertal stage in the mouse ovary.     

Regulatory role of inhibin in follicle-stimulating hormone secretion and folliculogenesis in the guinea pig.

The effects of unilateral and bilateral ovariectomy and passive immunization against inhibin on follicle-stimulating hormone (FSH) secretions and follicular development in the guinea pig were investigated. Bilateral ovariectomy decreased plasma immunoreactive (ir-) inhibin rapidly and increased plasma FSH significantly. Unilateral ovariectomy decreased plasma ir-inhibin and increased plasma FSH temporarily, and doubled the number of ova released from the remaining ovary at the subsequent ovulation in guinea pigs. Injection of 1.0 ml inhibin antiserum significantly increased concentrations of plasma FSH at 6 hr onwards and the number of small follicles (100-200 microm in diameter) at 48 hr after the injection in guinea pigs bearing progesterone-containing implants. In vitro bioassay showed that inhibin antiserum could neutralize the suppression of ovarian homogenate on FSH secretion from cultured rat anterior pituitary cells. These results confirm the evidence that the ovary is the main source of inhibin secretion and both in vitro bioassay and passive immunization against inhibin show that the inhibin is a major regulator in the follicular development through FSH secretion in guinea pigs.     

Pituitary and testicular responses of beef bulls to active immunization against inhibin alpha

Prepubertal crossbred beef bulls served as controls or were actively immunized against the N-terminal, 30-amino acid synthetic fragment of porcine inhibin alpha, pI alpha (1-30). Antibody titers were detected in sera (greater than 40% B/BO in sera diluted 1,000-fold) but not in rete testis fluid of 390-d-old bulls. Serum FSH and inhibin remained static during a 5-h intensive bleed; inhibin was not acutely affected by a 15-fold LH rise and a threefold FSH rise induced by exogenous GnRH. Serum FSH, but not LH or testosterone, was consistently elevated (P less than .05) in immunized bulls compared with control bulls. Neither pituitary weight, pituitary gonadotropin content nor pituitary FSH/LH ratios were affected (P greater than .10) by pI alpha(1-30) active immunization. Testicular sperm density was greater (60 x 10(6) vs 45 x 10(6) sperm/g testis; P less than .10) in immunized bulls, but testes weight, epididymides weight and total daily sperm production remained unchanged. These results suggest that inhibin is important for regulation of FSH secretion and testicular function. Immunization with suitable inhibin vaccines may improve bull fertility.     

Secretion of inhibin in female Japanese quails (Coturnix japonica) from hatch to sexual maturity

To clarify the cellular source and secretory pattern of inhibin in the Japanese quail during follicular development, the plasma concentrations of immunoreactive (ir) inhibin were measured from 1 to 7 weeks after hatching. Localization of the inhibin/activin alpha, beta A and beta B subunits was investigated by immunohistochemistry. To monitor development of the pituitary and ovarian functions, the plasma luteinizing hormone (LH) and progesterone concentrations were also measured. Ovarian weight increased gradually until 6 weeks of age and then abruptly increased at 7 weeks of age just at the onset of egg production. Plasma concentrations of LH increased significantly at 6 weeks of age. The plasma concentrations of ir-inhibin and progesterone and the pituitary contents of LH also increased significantly at 7 weeks of age. Immunohistochemically, the inhibin/activin alpha, beta A and beta B subunits were localized in the granulosa cells of all follicles during different stages of development from 1 to 7 weeks after hatching. The inhibin alpha, beta A and beta B subunits were also found in the interstitial cells but not theca cells of all follicles. These results demonstrated that the plasma concentrations of ir-inhibin of the female Japanese quails rose with ovarian development. The immunohistochemical results suggested that granulosa and interstitial cells are the major source of ovarian inhibins in female Japanese quails.     

Plasma progesterone in reindeer in relation to ovariectomy and hysterectomy

Four semi-domesticated reindeer were ovariectomized and 3 both ovariectomized and hysterectomized, 30-70 days before expected parturition. Anaesthesia with etorphine/propyonylphenthiazine was followed by an increase in the plasma concentration of progesterone of peripheral blood. The concentration of progesterone returned to pre-anaesthetic values before ovariectomy. Ovariectomy did not result in any substantial change in the plasma progesterone concentration within an observation period of 35-120 min. Hysterectomy was followed by a marked decrease in peripheral plasma progesterone within 60 min. The progesterone concentration in ovarian venous blood was slightly higher than the jugular venous blood in 1 animal and 150 and 400 times higher in the 2 other animals examined. Thus, despite lack of marked changes of progesterone in jugular venous blood upon ovariectomy, it is concluded that the ovaries are a major production site of progesterone in pregnant reindeer. The progesterone in uterine venous blood was close to that in the jugular vein in 1 animal, and slightly higher in 2 others. This observation, and the maintenance of pregnancy in spite of ovariectomy in 2 out of 4 animals, point to the foeto-placental unit as an additional source of progesterone production.     

Ovarian inhibition of peripheral plasma concentration of follicle stimulating hormone in prepuberal Holstein heifers

The objective of this study was to determine effects of age and castration on follicle stimulating hormone (FSH) secretion in prepuberal heifers. In experiment 1, twelve heifers were bilaterally ovariectomized at 3, 6, or 9 months of age (n = 4/group). Blood was collected at 10 min intervals for 8 hr at 1 week before ovariectomy and 1 and 4 weeks after ovariectomy. Frequency, amplitude and duration of FSH pulses were calculated. Mean plasma concentration of FSH (ng/ml), and frequency (pulses/8 hr), amplitude (ng/ml), and duration (min/pulse) of FSH pulses were not altered by age. Mean concentration of FSH increased (P less than .01) from 1 week before to 1 week and 4 weeks after ovariectomy, respectively, in all age groups. Pulse frequency increased (P less than .05) from 1 week before ovariectomy to 4 weeks after ovariectomy in 3 month old heifers, from 1 week before to 4 weeks after ovariectomy in 6 month old heifers, and from 1 week before to 1 week and 4 weeks after ovariectomy in 9 month old heifers. In experiment 2, twelve heifers were bilaterally ovariectomized at 3, 6 or 9 weeks of age (n = 4/group). Sample collection and measurement of mean concentration of FSH were the same as in experiment 1. Mean concentration of FSH increased (P less than .01) from 1 week before to 1 and 4 weeks after ovariectomy in heifers ovariectomized at 6 and 9 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of steroid hormone doses after ovariectomy on the peripheral hormone processes and uterine development in gilts. 2. Effects on gilts during early pregnancy

Experimental studies were conducted into ovariectomized pregnant gilts to establish effects of exogenic hormone administration, with endogenic ovarian steroids excluded, upon uterus and fetus development as well as on hormone levels in blood plasma, endometrium, and allantoic fluid. Hormone concentrations in blood plasma were found to depend clearly on hormone doses applied after ovariectomy to preserve pregnancy. 2 to 3 weeks of smooth gravidity, following ovariectomy, were ensured on the 6th or 14th day after KB1 by daily application of very low doses of progesterone only (80 mg) or in combination with estrogens, the ratio being 480:1.     

Inhibin activity in the mare and stallion

An overnight double antibody RIA, employing a rabbit antiserum raised to bovine 31 kDa inhibin (rAs-#1989, NICHD) and purified bovine 31 kDa inhibin (bINH-I-90/1, NICHD) as trace and standard, was validated to measure immunoreactive inhibin (iINH) concentrations in equine peripheral plasma, follicular fluid (FF), ovarian vein (OV) plasma, testicular tissue extracts (TTE) and testicular vein (TV) plasma. The dynamic relationship of iINH and follicle stimulating hormone (FSH) was investigated during the estrous cycle of the mare and the annual reproductive cycle of the stallion.In the RIA, parallel dose-response curves were observed between the bovine inhibin standard and serial dilutions of equine FF, OV, TTE, TV and plasma. The average recovery of a known amount of purified bovine inhibin added to gelding plasma was approximately 100%. In the inhibin bioassay, serial dilution of equine FF and TTE were observed to be parallel to the bovine inhibin standard. A five-fold difference (p<0.05) between jugular and gonadal vein plasma iINH concentrations was observed in the mare and an eight-fold difference (p<0.05) was observed in the stallion. Plasma levels of iINH in ovariectomized mares or geldings were undetectable in the RIA.Concentrations of FSH, estradiol and iINH changed significantly in the mare during the estrous cycle (p<0.05). Immunoreactive inhibin levels were highest (0.54 ± 0.06 ng/ml) on the day of ovulation, declined rapidly following ovulation and reached a nadir (0.21 ± 0.03 ng/ml) on day 7 post-ovulation. Plasma iINH and estradiol concentrations followed a similar profile and were found to be positively correlated (r=0.7064; p<0.01), whereas iINH and FSH levels demonstrated an inverse relationship (r=−0.7359, p<0.01) throughout the estrous cycle. Concentrations of FSH were also inversely related (−0.8498, p<0.01) with estradiol during the cycle. In the stallion, plasma iINH and FSH levels changed significantly during the year (p<0.05). The iINH profile reflected seasonal changes in testicular activity, with highest concentrations in late spring (3.37 ± 0.44 ng/ml) and lowest concentrations in the fall (2.21 ± 0.33 ng/ml). Plasma concentrations of iINH were positively correlated (r=0.7691, p<0.01) with FSH concentrations throughout the year.In conclusion, a specific and sensitive RIA for iINH has been validated for plasma and biological fluids in the horse. Furthermore, the gonads appear to be the source of bioactive and immunoreactive inhibin as observed in other species. The dynamic relationship between iINH and FSH that is present in both the mare and stallion suggests that iINH may be a useful marker of gonadal activity in this species.     

Suckling inhibits release of luteinizing hormone-releasing hormone from the bovine median eminence following ovariectomy

The effect of suckling on depletion of hypothalamic LHRH from the median eminence (ME) following ovariectomy (OVX) was determined in cattle. Multiparous, postpartum Holstein cows were assigned randomly to three groups: intact, nonsuckled (INT, n = 4); ovariectomized (3 to 5 d after parturition), nonsuckled (OVX, n = 4); and ovariectomized (3 to 5 d after parturition) and suckled by three calves (OVX-S, n = 5). Blood samples were collected at three periods (1 to 7 d before parturition and 3 to 5 d and 31 to 37 d after parturition) to determine plasma LH concentration. At 31 to 37 d after parturition, all cows were slaughtered and each ME was collected and mid-sagitally sectioned. The left half of each ME was used to determine content and concentration of LHRH. Concentrations of LH and LHRH were determined by RIA. Plasma LH concentration was similar among the three groups at 1 to 7 d before parturition and 3 to 5 d after parturition; however, at 31 to 37 d after parturition, OVX cows had a greater (P less than .05) concentration of LH (2.25 +/- .64 ng/ml) than either INT (.47 +/- .10 ng/ml) or OVX-S (.92 +/- .14 ng/ml) cows. Content of LHRH in the ME of INT (80.12 +/- 15.0 ng) and OVX-S 109.8 +/- 16.4 ng) cows was similar but was greater (P less than .05) than that in OVX cows (48.95 +/- 5.9 ng).(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxytocin mediates some effects of insulin-like growth factor-I on porcine ovarian follicles

The aims of the present study were (1) to investigate the influence of insulin-like growth factor-I (IGF-I) on follicular size, on the secretion of oxytocin (OT), progesterone (P), estradiol (E), IGF binding protein-3 (IGFBP-3), inhibin A, inhibin B and cAMP and on the expression of proliferation-associated peptide PCNA, ERK-related mitogen activated protein kinase (MAPK/ERK1, 2) and protein kinase A (PKA) in cultured porcine ovarian follicles; (2) to examine the effects of OT on IGF-I and on these functions; and (3) to determine whether the effects of IGF-I can be mediated by OT. To define the involvement of OT in mediating IGF-I action, we compared responses of porcine ovarian follicles to IGF-I and OT and examined whether blockade of endogenous OT by specific antiserum can affect IGF-I action. It was observed that IGF-I (1, 10 or 100 ng/ml) was able to prevent a decrease in the size of ovarian follicles during culture and caused an increase in the diameter of some follicles. It also stimulated the secretion of OT, P, IGFBP-3, inhibin A and cAMP, decreased the secretion of E and inhibin B (RIA/EIA/ELISA), and induced the expression of PCNA, PKA, MAPK/ERK1, but not MAPK/ERK2 (Western blotting). Like IGF-1, OT (100 ng/ml) prevented decrease in follicular size and increased the diameter of some follicles. It also stimulated the secretion of P and IGF-I, but not E. Antiserum against OT (1%), when given alone, did not affect the reduction of follicular size but slightly increased the percentage of follicles increasing their diameter during culture. The antiserum also inhibited secretion of OT and cAMP but not the secretion of P, E, IGFBP-3 or the expression of PKA, MAPK/ERK1 or 2. When given together with IGF-I, the antiserum prevented the stimulatory action of IGF-I on the proportion of enlarged follicles and on OT, IGFBP-3 and MAPK/ERK1. It augmented the effect of IGF-I on P, but not the effect on E, cAMP, PKA or MAPK/ERK2. These observations demonstrate the involvement of IGF-I and OT in the control of ovarian follicular size and follicular cell proliferation, progestagen, estrogen, IGFBP-3, inhibin A and B secretion and in cAMP/PKA- and MAPK/ERK1-dependent intracellular mechanisms. Furthermore, the reciprocal stimulation of IGF-I and OT and the similarity of some their effects, together with the prevention or augmentation of some IGF-I effects after OT blockade, suggest that IGF-I action can be mediated by OT.     

Immunization of goats against inhibin increased follicular development and ovulation rate

In the present study, two experiments were conducted to induce superovulation in goats using passive and active immunization against inhibin. In the first experiment, two groups of goats were given an intravenous injection of either 10 ml normal goat serum (control; n=6) or inhibin antiserum developed against [Tyro30]-inhibin alpha (1-30) (passively immunized; n=6) 48 h before treatment with PGF2alpha. In the second experiment, two groups of goats were immunized with inhibin vaccine (actively immunized; n=5) or Freund's adjuvant (control; n=5) followed by three booster immunizations at 4 week intervals. Blood samples were collected for determination of FSH, LH, estradiol-17beta, and progesterone. Ultrasonography was used to determine ovarian activity at PGF2alpha injection and ovulation rate one week after estrus. In both experiments, there was a significant increase in plasma FSH concentration compared with the controls. However, the pattern of the FSH levels was different between the passively and actively immunized goats. The numbers of follicles in passively and actively immunized goats (22.4 +/- 2.3 and 18.6 +/- 2.1, respectively) were significantly greater than those in the controls (2.6 +/- 0.4 and 2.3 +/- 0.4, respectively). In addition, the ovulation rate was greater in the immunized animals compared with the controls. Therefore, either passive or active immunization against inhibin could be used to induce superovulation in goats.     

去势对白来航母鸡垂体和肾上腺的影响

垂体和肾上腺在摘除卵巢的雌性动物性激素合成过程中起到重要作用。为研究去势对白来航母鸡垂体和肾上腺的影响,实验对6只9周龄白来航母鸡进行卵巢摘除手术,饲养至97周龄时,检测去势白来航母鸡与同周龄未去势母鸡的血清性激素水平、冠高和距长,比较分析垂体重、肾上腺重差异,并检测垂体发育相关基因GREB1的表达量。结果显示:去势母鸡雌二醇浓度(P<0.05)、肾上腺重量(P<0.01)以及GREB1相对表达量(P<0.05)低于未去势母鸡;冠高、距长和垂体重量高于未去势母鸡(P<0.05)。可见,摘除母鸡卵巢可抑制肾上腺发育,促进垂体发育。     

Passive immunoneutralization of endogenous inhibin increases ovulation rate in miniature Shiba goats

We reported previously that passive immunization against inhibin enhances follicular growth and increases the ovulation rate. However, the ovulation rate was not comparable to the number of follicles. Therefore, the aim of this study was to attempt to increase the ovulation rate by increasing the interval between inhibin immunization and PGF2alpha injection. Five miniature Shiba goats were treated with 10 ml inhibin antiserum (inhibin-AS) developed against [Tyro30]-inhibin alpha (1-30). A control group (n=5) was treated with normal goat serum. All animals were injected intramuscularly with 125 microg PGF2alpha 72 h after treatment to induce estrus and ovulation. Blood samples were collected for hormonal assay and the ovulation rate was determined by laparotomy. In contrast to the control group, there was a significant increase in plasma concentrations of FSH in the immunized group. After luteolysis, plasma concentrations of estradiol-17beta increased markedly to a preovulatory peak about 2 folds higher (P<0.01) than that of controls. In addition, the ovulation rate was greater in the immunized group (14.4 +/- 2.2) than in the control group (2.2 +/- 0.6), and the mean number of follicles > or = 4 mm in diameter was 10.0 +/- 0.8 in the inhibin-AS group compared with 2.4 +/- 0.3 in control group. The present results demonstrate that immunoneutralization of endogenous inhibin increased FSH secretions in miniature shiba goats. The increased FSH secretion enhanced follicular growth and increased the ovulation rate. Additionally, increasing the interval between inhibin-AS and PGF2alpha injections (to 72 h) resulted in a greater ovulation rate compared with the previous protocol (48 h). Therefore, inhibin-AS treatment proved to be an effective alternative to exogenous gonadotropin methods for induction of superovulation in goats.     

Effects of age,season, and fertility status on plasma and intratesticular immunoreactive (IR) inhibin concentrations in stallions

The nature of the relationship between inhibin and reproductive function in the stallion is yet to be elucidated. Blood and testes from 51 light horse stallions ranging in age from 2 mo to 25 years were collected during the breeding and nonbreeding seasons to study the effects of testicular maturation, aging, season, and fertility status on peripheral and intratesticular concentrations of Ir inhibin and other reproductive hormones. Of the 51 stallions, 12 age-matched stallions (6 fertile, 3 subfertile, and 3 infertile) were used in the fertility study. Blood samples were taken before castration and plasma stored at −20°C for analysis of Ir inhibin, luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), estradiol (E₂), and estrogen conjugates (EC) by radioimmunoassay (RIA). Testes were homogenized and testicular extracts prepared and frozen at −70°C for analysis of Ir inhibin, T, E₂, and EC by RIA. Plasma concentrations of Ir inhibin, LH, FSH, T, E₂, and EC and intratesticular concentrations of Ir inhibin, T, E₂, and EC increased with age (P < 0.01). The most dramatic effect appeared to be during testicular maturation. An aging effect was not observed in adult stallions. A seasonal effect was not detected for any of the plasma hormones, whereas for the intratesticular hormones the only change noted was an increase in T in the nonbreeding season (P < 0.05). Plasma Ir inhibin, E₂, and EC were lower (P < 0.01) and gonadotropins higher (P < 0.05) in infertile stallions. Plasma T levels did not change. Intratesticular Ir inhibin concentrations tended to be lower (P < 0.1) in subfertile stallions and significantly lower (P < 0.01) in infertile stallions, whereas intratesticular steroid levels were not different among the three groups. In conclusion, plasma and intratesticular Ir inhibin concentrations seem to be affected by testicular maturation and fertility status.     

Role of ovarian progesterone and potential role of prostaglandin F2alpha and prostaglandin E2 in modulating the uterine response to infectious bacteria in postpartum ewes

In sheep and cattle, the postpartum uterus is resistant to bacterial challenge until after corpora lutea develop. A 2 x 2 factorial arrangement of treatments was used to determine whether prostaglandins may mediate the effects of progesterone in transforming the postpartum uterus from resistant to susceptible. On d 14 postpartum, ewes (n = 6/group) were ovariectomized or sham ovariectomized, and the vena cava was catheterized for daily collection of uteroovarian-enriched blood. From d 15 to 20, ewes received twice daily intramuscular injections of progesterone in sesame oil or plain sesame oil. On d 20, each uterus received 75 x 10(7) cfu of Arcanobacterium pyogenes and 35 x 10(7) cfu of Escherichia coli. Uteri were collected on d 25 and examined for signs of infection. For each blood sample, unstimulated and mitogen-stimulated lymphocyte proliferation was measured as [3H]thymidine incorporation, smears were prepared for differential white blood cell (WBC) counts, and progesterone, prostaglandin F2alpha, (PGF2alpha), and prostaglandin E2 (PGE2) were quantified. All 12 progesterone-treated, but only two of the 12 oil-treated, ewes developed uterine infections (P < 0.001). Progesterone treatment increased (P < 0.001; 3.1 vs 1.5 ng/mL) and ovariectomy decreased (P < 0.001; 3.7 vs 0.9 ng/mL) vena caval progesterone. Progesterone treatment reduced (P < 0.01) PGF2alpha, (303.9 vs 801.3 pg/mL), and PGF2alpha was greater (P < 0.05) before than after inoculation (626.4 vs 478.8 pg/mL). The PGE2 concentration was greater in progesterone-treated, ovary-intact ewes than in ewes in the other groups (ovariectomy x progesterone treatment; P < 0.01). Ovariectomy increased (P < 0.005; 4.4 vs 2.9 pmol) and progesterone treatment decreased (P < 0.05; 3.2 vs 4.1 pmol) concanavalin A-stimulated lymphocyte proliferation. Ovariectomy increased lipopolysaccharides-stimulated proliferation (P < 0.05; 2.4 vs 1.9 pmol). For neutrophils per 100 WBC, the ovariectomy x progesterone and progesterone x period interactions were significant (P < 0.01). The ovariectomy x progesterone interaction was significant (P < 0.01) for lymphocytes per 100 WBC. Ovariectomy decreased monocytes (P < 0.001; 10 vs 13) and increased eosinophils (P < 0.001; 10 vs 5) per 100 WBC. Progesterone makes the postpartum uterus in ewes susceptible to infection, but ovariectomy allows ewes to remain resistant; uterine prostaglandins may mediate this change. This model creates opportunities to determine the mechanisms responsible for the shift from resistance to susceptible.     

抗α-INF卵黄抗体的制备与鉴定

用人抑制素 ( 1 -2 6 )Tyr.Gly与KLH连接作免疫原 ,免疫本地良种母鸡 ,旨在获得大量抗抑制素卵黄抗体 (eIgY)。实验中 ,收集鸡蛋 ,观察了血清及卵黄中特异性抗体的应答 ,结果经免疫的鸡有免疫应答 ,所产卵的卵黄中可检出大量的有高度活性的抗体。综合运用pH值 ,非球蛋白沉淀法和球蛋白沉淀法 ,制得纯度较高的抗抑制素eIgY。采用阻断ELISA法证实所获得的eIgY具有高度的特异性。用eIgY被动免疫未成年昆明鼠 ,子宫重量明显增加。由此得出结论可以用鸡做生物反应器大量生产抗抑制素抗体 ,用于被动免疫家畜来提高家畜繁殖率     

Evaluation of adrenal function in psittacine birds, using the ACTH stimulation test

The effect of ACTH (16 units) on plasma cortisol and corticosterone concentrations in healthy psittacine birds was evaluated. Plasma corticosterone significantly increased (P less than 0.01) from a mean (+/- SD) basal concentration of 3.25 +/ 3.6 ng/ml to 26.47 +/- 9.25 (one hour after ACTH administration) and 25.69 +/- 13.23 ng/ml (2 hours after ACTH administration). For maximal increase in plasma corticosterone as measured by radioimmunoassay (RIA), heat denaturation was necessary to release corticosteroids from steroid-binding proteins. As measured by RIA, plasma cortisol concentrations did not increase, whether or not the heat denaturation step was included. Addition of cortisol to avian plasma did not prevent accurate quantification of cortisol as measured by RIA. Plasma corticosterone concentrations in cockatoos, macaws, Amazon parrots, conures, and lorikeets before and after ACTH administration indicated that the ACTH stimulation test could be used to evaluate adrenal secretory capacity in psittacine birds.     

Is nutritional anestrus precipitated by subfunctional corpora lutea in beef cows?

Thirty-four multiparous, lactating, cyclic beef cows which calved in moderate body condition were used to determine effects of restricted nutrition on corpus luteum (CL) development and endocrine status. At 78 d postpartum, six cows were assigned to a control (CON) diet (26.0 Mcal ME), fed to increase bodyweight (BW) and body condition score (BCS), and the remaining 28 cows were fed to lose BW and BCS on a restricted (RES) diet (14.0 Mcal ME). Following a 40-d adjustment period on respective diets, estrous cycles were synchronized and cows bled daily for determination of progesterone (P4), luteinizing hormone (LH) and insulin (INS) beginning at the synchronized estrus. Ultrasonography was used to determine the ovulatory follicle and CL development. Control cows were maintained for one estrous cycle and were ovariectomized on day 11 of their second cycle. Ten cows on restricted diet (RES-C) continued to form a functional CL (P4 > 1.5 ng/ml at day 10 of an estrous cycle) through as many as 5 cycles, after which observations were discontinued. Fourteen cows on restricted diet (RES-A) were ovariectomized on day 11 of a cycle when a CL was identified by ultrasonography, but was subfunctional (P4 < 1.5 ng/ml on day 10 of that cycle). Four additional RES-A cows which had subfunctional CL were not ovariectomized but were bled for an additional 25 d. At ovariectomy, CL and ovarian weights were collected. Luteal tissue was prepared for evaluation of P4 synthesis, LH responsiveness in vitro, and for determination of P4 content and total LH receptors. Bodyweight and BCS increased in CON cows; whereas, RES cows lost BW and BCS (P < .05). In the cycle prior to ovariectomy, serum P4 and LH were not different in 18 RES-A cows which developed subfunctional CL in comparison to CON cows. Four RES-A cows not ovariectomized but bled for an additional 25 d neither exhibited estrus, ovulated, nor had P4 concentrations greater than .3 ng/ml. Serum INS was lower in RES-A cows during the cycle prior to ovariectomy than in CON cows (P < .05). During the 11-d period prior to ovariectomy, mean serum P4 and INS were lower in RES-A cows than in CON cows (P < .05); however, serum LH was not different. Furthermore, CL and ovarian weights, P4 content of CL, secretion of P4 by luteal tissue in response to LH in vitro and LH receptor number were not different between CON and RES-A cows. In conclusion, nutritional anestrus may be preceded by the formation of a CL with lower steroidogenic output in vivo. However, luteal tissue, collected from RES-A cows, did not appear to be subfunctional during in vitro incubation when substrate availability and gonadotropin support were equal between diets.     

Physiological roles of inhibin in regulation of FSH secretion and follicular development during early pregnancy in goats

The aim of the current study was to clarify the physiological role of inhibin in controlling FSH secretion and follicular development during the early pregnancy in goats. Eight goats investigated sonographically on Days 19-21 (Day 0=day of mating) for pregnancy were assigned into control (n=3) and treated (n=5) groups. The ovaries of all animals were daily scanned with ultrasound for follicles 2mm or more in diameter from 1 day before to 5 days after treatment. On Day 25 postbreeding; animals received either 10 ml, of normal goat serum or antiserum against [Tyr (30)]-inhibin alpha (1-30). Jugular blood samples were collected every 6 h starting 24 h before and until 120 h after treatment. The plasma concentration of FSH increased at 6 h and remained at significantly high levels until 120 h in treated vs. control group. The plasma concentrations of estradiol showed a marked increased at 66 h, with peak levels at 120 h after treatment of antiserum. The basal concentrations of LH and the pattern of plasma concentrations of progesterone were not significantly different between the two groups. The number of medium size (3.5-5.0 mm) follicles increased considerably from Day 2, whereas small (3.5 mm or less) and large (5 mm or more) follicles increased noticeably from Day 3, as compared with pre-treatment and controls. These results clearly indicated that inhibin is a key hormone in regulation of follicular development through regulation of endogenous FSH secretion during early pregnancy in goats.