Food deprivation stimulates the luteolytic capacity in the gilt

The aims of this study were to study the effects of fasting on progesterone (P4) production in the pig and to verify whether fasting influences luteal expression of PGF(2alpha) receptor (FPr) and prostaglandin secretion. Superovulated prepubertal gilts were used; half of them were fasted for 72h starting on day 2 (F2) or 9 (F9) of the induced estrous cycle, respectively, while two groups (C2 and C9) served as respective controls. Plasma P4 and PGFM concentrations were determined by RIA while FPr mRNA expression in CLs collected at the end of fasting period was measured by real-time PCR. In experiment 1, plasma P4 concentrations in fasted gilts were significantly (P<0.01) higher than in controls starting from day 3 (F2; n=6) and 10 (F9; n=6). FPr mRNA expression was similar in F2 and C2 (n=6) CLs while it was significantly (P<0.05) higher in F9 than in C9 (n=6) CLs. In experiment 2, cloprostenol administered on day 12 significantly (P<0.05) increased FPr mRNA expression in CLs from both F9 (n=6) and C9 (n=6) gilts. At the time of cloprostenol injection PGFM levels were significantly higher (P<0.05) in the fasted group and cloprostenol-induced luteolysis in fasted but not in normally fed gilts. Results from this study indicate that fasting in prepubertal gilts induced to ovulate stimulates luteal P4 and PGFM production as well as FPr mRNA expression, thus increasing luteolytic susceptibility.     

An association of faecal egg counts and prolactin concentrations in sera of periparturient Angora goats.

Faecal egg counts and serum prolactin concentrations in 13 pregnant and five non-pregnant Angora goats were monitored over a period of 20 weeks. The mean weekly egg counts of pregnant goats were significantly higher (P less than 0.01) than those of non-pregnant goats. In pregnant goats the mean egg counts in the 6 week post-partum period were significantly higher (P less than 0.01) than those of 6 weeks prepartum. The mean prolactin concentration of pregnant goats during the 6 week post-partum period was significantly higher (P less than 0.01) than that of 6 weeks pre-partum. During the 6 to 3 weeks before parturition, the prolactin values generally remained low (below 100 ng ml-1). The rise in prolactin concentration started between 3 weeks and 1 week before parturition. Only in pregnant goats was there a positive linear regression between prolactin levels and faecal egg counts.     

母鸡抑制素的产生

母鸡抑制素主要是由排卵前卵泡颗粒细胞产生的,肾上腺是又一来源,ＬＨ在刺激体外颗料细胞产生抑制素方面的比ＦＳＨ有效。去除排卵前卵泡后,血浆免疫活性抑制素显著降低,而血浆ＦＳＨ急剧升高。卵泡颗粒层中,抑制素α亚基比β（Ａ）亚基表达充分。α亚基是由近似１．７ｋｂ的ｍＲＮＡ编码,主要的８．４ｋｂβ（Ａ）－ｍＲＮＡ带在排卵前卵泡的颗粒层中表达。     

Enhancing Embryo Yield in Superovulated Holstein Heifers by Immunization Against Inhibin

Eight heifers, aged 16–17 months and showing normal oestrous cycles, were immunized against a recombinant porcine inhibin α subunit immunogen, together with another 10 heifers of the same age as controls and treated with placebo immunogen. Primary (1 mg immunogen) and two booster (0.5 mg immunogen each) immunizations were administered at 28‐day intervals. Ten days after the second booster immunization, both groups of heifers underwent a superovulation treatment. Each animal was given an intravaginal progesterone releasing sponge, which was withdrawn 7 days following an i.m. injection of 0.5 mg cloprostenol. Heifers were treated with FSH for 4 days and artificially inseminated after oestrus occurred. The embryos were flushed and evaluated 7 days after insemination. Immunization significantly (p < 0.01) increased blood antibody titres against recombinant porcine inhibin α subunit, from pre‐immunizaion and control values of approximately 0.06 of ELISA 450 nm reading to 0.6 to 0.7 after two or three immunizations. The immunized heifers produced on average 15.8 ± 2.8 embryos, significantly (p < 0.05) higher than the yield of 8.3 ± 1.5 in the controls. The number of transferable embryos were non‐significantly higher in immunized than in control heifers (9.6 ± 3.1 vs 5.8 ± 1.6, p > 0.05). The peak plasma oestradiol concentrations were significantly higher in immunized than in control heifers, both immediately after FSH treatment and 20 days thereafter. Plasma P4 concentrations after superovulation were in the range of 20 ng / ml in the immunized heifers, significantly (p < 0.05) higher than the values approximately 15 ng / ml in control heifers. These results indicated that prior immunization against inhibin α subunit stimulated production of antibodies against inhibin, which enhanced follicular developmental response to superovulation and lead to higher yield of total and transferable embryos. Therefore immunization combined with the conventional superovulatory gonadotrophin treatment, can be a simple and efficient method to produce low cost bovine embryos.     

The effects of prolactin and gonadotropin on luteal function and morphology in the cyclic golden hamster

The present study was conducted to evaluate the endocrinological effects of the pituitary on luteal maintenance and regression in the cyclic golden hamster (Mesocritus auratus). After hypophysectomy (Hypox) at 0900 h on day 1 of the estrous cycle (the day of ovulation), the animals received injection of prolactin (PRL) or PRL plus equine chorionic gonadotropin (eCG). They were decapitated at 1500 h on day 3 of the cycle, and trunk blood was collected for measurement of progesterone (P4). Corpora lutea (CLs) were dissected from one ovary for DNA ladder detection by electrophoresis, determination of DNA fragmentation ratio by fluorometric measurement method and measurement of P4. The other ovary was used for histological observation. After the Hypox, the daily injection of 1 mg ovine PRL restrained the DNA fragmentation ratio and number of apoptotic cell in the CLs. The PRL treatment maintained the luteal morphology and increased the luteal P4 concentration, but not in the plasma P4 concentration. In addition to PRL, injection of 2 IU eCG after the Hypox also restrained the DNA fragmentation ratio and number of apoptotic cells in the CLs to the level of a pregnant animal. The PRL plus eCG treatment maintained the luteal morphology in the same manner as the PRL only treatment and increased not only the luteal but also the plasma P4 concentration. These results suggest that PRL restrains luteal apoptosis and maintains luteal morphology and that the combination of PRL and eCG restrains not only structural but also functional luteal regression in the cyclic hamster.     

Effect of Pregnancy and Foetal Number on Diameter of Corpus Luteum,Maternal Progesterone Concentration and Oxidant/Antioxidant Balance in Ewes

The aim of this study was to determine the changes in diameter of corpus luteum (CL), maternal progesterone (P) concentration, lipid peroxidation and non‐enzymatic antioxidant levels along with enzymatic antioxidant activities in pregnant ewes bearing single and twin foetuses. The ewes were selected from healthy animals that were brought to the abattoir for slaughtering. The ewes were divided into three groups: Group 1 (non‐pregnant, non‐oestrous, n = 30), Group 2 (pregnant bearing a single foetus, n = 30) and Group 3 (pregnant bearing twin foetuses, n = 12) after they were slaughtered. Pregnant ewes were in the first half of the pregnancy. The diameter of CL and P concentration of pregnant ewes bearing a single foetus or twin foetuses were found higher than that found in non‐pregnant ewes. Similarly, the P concentration of pregnant ewes bearing twin foetuses was higher than that found in pregnant ewes bearing a single foetus. Malondialdehyde (MDA) level in pregnant ewes bearing twin foetuses was higher than that found in both non‐pregnant and pregnant ewes bearing a single foetus. The serum glutathione (GSH) level and glutathione‐peroxidase (GSH‐Px) activity of pregnant ewes bearing twin foetuses were found lower than that found in non‐pregnant ewes. Additionally, the GSH‐Px activity of pregnant ewes bearing twin foetuses was found lower than that found in pregnant ewes bearing a single foetus. No significant difference was found between pregnant ewes bearing female and male foetus with respect to diameter of CL, P concentration and oxidative stress parameters. There were significant positive correlations between foetal number (0, 1, 2) and diameter of CL, P concentration, MDA level, and between P concentration and diameter of CL, MDA level. However, significant negative correlations were found between foetal number (0, 1, 2) and GSH level, GSH‐Px activity, and between P concentration and GSH‐Px activity. In conclusion, the diameter of CL enlarges, P production increases and oxidant/antioxidant balance impairs because of the gestation stress in ewes during pregnancy.     

Downregulation of the expression of inhibin α subunit and betaglycan in porcine cystic follicles

Inhibins, as members of the transforming growth factor beta (TGF-β) superfamily, downregulate the synthesis and secretion of follicle-stimulating hormone (FSH) in an endocrine manner. The role of inhibin/betaglycan in the ovary regulation recently gained attention. To date, no data exist on the function of inhibin α subunit and betaglycan in cystic follicles. In this study, the expressions of inhibin α subunit and betaglycan in cystic follicles were investigated using immunohistochemistry, real-time PCR and Western blot analysis. Both inhibin α subunit and betaglycan immunoreactivities were mainly localized in the granulosa cells of follicles. Expression of inhibin α subunit and betaglycan was inferior in cystic follicles compared with that in normal large follicles. However, the result of enzyme-linked immunosorbent assay showed no significant difference in the decreasing in concentration of inhibin α subunit in cystic follicular fluid compared with the control (P>0.05). In this study, we explored the effects of FSH on betaglycan expression in granulosa cells in vitro. As expected, a significant increase in the expressions of betaglycan mRNA and protein in granulosa cells was observed in response to exogenous FSH (30 ng/ml) (P<0.05) compared with the control. Consequently, this study provides evidence that the expressions of inhibin α subunit and betaglycan are inferior in cystic follicles, and this may be caused by the decrease in FSH in the presence of a cystic follicle.     

Changes in the concentration of mRNAs for the inhibin subunits in ovarian follicles after administration of gonadotropins to progestin treated ewes.

RNA was extracted from single or small groups of ovine ovarian follicles after treatment of ewes with FSH and/or LH. The content of mRNA for the alpha-inhibin and beta A-inhibin subunits was analyzed by hybridization with specific cDNA probes. All ewes were treated with progestin vaginal pessaries to suppress spontaneous preovulatory follicle maturation and ewes were given three intramuscular injections of gonadotropins at 8-hr intervals starting 24 hr prior to collection of ovaries. In experiment I, both Schering-FSH and NIDDK-oFSH-17 (oFSH) significantly increased alpha- and beta A-inhibin mRNA per ewe in 2-5 mm follicles and tended to increase alpha- and beta A-inhibin mRNA in large (greater than 5 mm) follicles. In experiment II, oFSH and NIDDK-oLH-25 (oLH) were administered in a 2X2 factorial arrangement. Separate administration of oFSH or oLH increased (P less than .05) the alpha-inhibin mRNA concentration in large follicles. alpha-inhibin mRNA concentration in 4-5 mm follicles was also increased by oFSH but was decreased by oLH. Concomitant treatment with oFSH and oLH did not change alpha-inhibin mRNA concentrations from those measured in oFSH treated ewes. In experiment II, beta A mRNA concentrations followed a pattern similar to that of alpha A mRNA, but the differences were not statistically significant. We conclude that, in the ewe, exogenous FSH increases the concentration of inhibin mRNA in the whole follicle. The ability of exogenous oLH to alter expression of the inhibin subunit genes may depend upon the stage of follicle maturation.     

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.     

Expression of Genes Associated with Apoptosis in the Porcine Corpus Luteum During the Oestrous Cycle

The corpus luteum (CL) of the pig lacks luteolytic sensitivity (LS) to prostaglandin (PG) F‐2α until after day 12 of the oestrous cycle, but the mechanisms underlying this phenomenon are poorly understood. As luteolysis involves apoptosis, we hypothesized that critical apoptotic proteins may be deficient in CLs that lack LS. The specific aim of these studies was to examine mRNA expression and protein levels of apoptosis genes/proteins (BAX/Bax, BCLX/Bcl‐x, CASP3/Caspase‐3, CASP8/Caspase‐8, NFΚB1/NFκB, TP53/p53) in porcine CLs collected at different stages of the oestrous cycle. CLs were collected surgically, mRNA and protein extracted, and expression/levels analyzed by semi‐quantitative (SQ) PCR and Western blots, respectively. At the mRNA expression level, only BAX (maximal on day 4) and TP53 (maximal on day 7) showed significant variations during the oestrous cycle. At the protein level, only Bcl‐x and Caspase‐3 showed significant changes during the cycle; Bcl‐x decreased on day 13 and Caspase‐3 increased on day 13. It is concluded that apoptosis‐associated proteins (i.e. Bcl‐x and Caspase 3) may play a critical role in luteolytic sensitivity in the pig.     

The Possible Involvement of Salsolinol and Hypothalamic Prolactin in the Central Regulatory Processes in Ewes During Lactation

Salsolinol, a dopamine‐related compound and prolactin‐producing cells were found in the ovine hypothalamus. This study was designed to test the hypothesis that salsolinol, acting from the CNS level, is able to stimulate pituitary prolactin release as well as prolactin mRNA expression in the anterior pituitary cells (AP) and in the mediobasal hypothalamus (MBH) in lactating ewes. The intracerebroventricular infusions of salsolinol in two doses, total of 50 ng or 5 μg, were performed in a series of five 10‐min infusions at 20‐min intervals. All infusions were made from 12:30 to 15:00 and the pre‐infusion period was from 10:00 to 12.30 h. The prolactin concentration in plasma samples, collected every 10 min, was determined by radioimmunoassay; prolactin mRNA expression in AP and MBH tissues was determined by real‐time PCR. The obtained results showed that salsolinol infused at the higher dose significantly (p < 0.001) increased plasma prolactin concentration in lactating ewes, when compared with the concentration noted before the infusion and with that in lactating controls. In lactating ewes, the relative levels of prolactin mRNA expression in the AP and MBH were up to twofold and fivefold higher respectively than in non‐lactating ewes (p < 0.05). In our experimental design, salsolinol did not significantly affect the ongoing process of prolactin gene expression in these tissues. We conclude that in ewes, salsolinol may be involved, at least, in the process of stimulation of prolactin release during lactation and that hypothalamic prolactin plays an important role in the central mechanisms of adaptation to lactation.     

Inhibin-like activity in plasma from ovariectomized ewes and serum albumin: pitfalls for radioimmunoassay.

Progress to understand mechanisms that regulate inhibin secretion and action in farm animals has been handicapped by the shortage of simple, accurate assay methods to quantify inhibin in circulation. RIA would seem to provide the needed quantitative capability, but results of the following studies using inhibin RIA procedures reveal reasons to interpret inhibin immunological potency estimates with caution. Two sets of inhibin RIA reagents and various assay buffers were used. Initially, inhibin immunoactivity was estimated with an antiserum to a 32 amino acid peptide fragment from the alpha subunit of porcine inhibin [pI alpha(1-32)] and tracer to the peptide with tyrosine added in position 0 to permit radioiodination, pI alpha(Tyr1-32). Later, an antiserum to pI alpha(1-29Tyr30) peptide and pI alpha(1-29Tyr30) tracer was evaluated as were several combinations of assay buffer and assay conditions. Both sets of assay reagents provided quantitative recovery of pI alpha(1-32) peptide from plasma, parallel response between the peptide and either ovine or bovine plasma, as well as adequate sensitivity to measure inhibin immunoactivity in 25 microliters of plasma. However, plasma from long-term ovariectomized female sheep, swine or cattle appeared to contain nearly as much inhibin immunoactivity as intact animals. To explore the possibility that the adrenals may produce sufficient inhibin to account for unexplained high levels of inhibin immunoactivity in plasma from ovariectomized animals, ewes on days 12 and 13 of the estrous cycle were injected with either corn oil (CONT) or large doses of an adrenal steroid agonist, dexamethasone (DEX), to alter adrenal function. Likewise, ewes were either ovariectomized (OVX) on day 12 or injected on days 12 and 13 with estradiol-17 beta plus progesterone (E2 + P4) to alter ovarian function. The plasma concentration of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) increased following ovariectomy (P less than .001), and LH decreased following ovarian steroids (P less than .001). Treatment with DEX did not change plasma gonadotropin values (P greater than .1). When plasma was assayed using pI alpha(1-32) reagents and an assay buffer consisting of gelatin/phosphate/Tween-20 (GelT20), inhibin immunoactivity was not affected by any of the four treatments (P greater than .1), even including ovariectomy. Re-assay of these same samples with an RIA procedure that used gelT20 assay buffer and pI alpha(1-29Tyr30) reagents produced good agreement with the previous assay (partial correlation P less than .0001), but there was no statistical evidence that ovariectomy or treatment with ovarian or adrenal steroids changed the level of immunoassayable inhibin in plasma.(ABSTRACT TRUNCATED AT 400 WORDS)     

Regulation of endometrial granulocyte macrophage-colony stimulating factor (GM-CSF) in the ewe

Granulocyte macrophage-colony stimulating factor (GM-CSF) increases ovine interferon-tau (oIFNtau) secretion by ovine conceptuses, but endometrial production of GM-CSF has not been characterized. Endometrial GM-CSF expression was evaluated in ovariectomized ewes implanted with estradiol-17beta (E(2)) and/or progesterone (P(4)) for 14 days, in day 14 cyclic and day 14 pregnant ewes. Relative levels of endometrial GM-CSF mRNA were 3-fold higher in E(2)- and E(2)/P(4)-treated ewes than that of control or P(4)-treated ovariectomized ewes. Levels of endometrial GM-CSF mRNA for cyclic ewes were similar to E(2)- and E(2)/P(4)-treated ewes, but amounts of GM-CSF mRNA in pregnant ewes were 2-fold higher. GM-CSF concentrations in endometrial culture media, determined by GM-CSF bioassay, for cyclic and E(2)/P(4)-treated ovariectomized ewes were 3-fold higher than those of control, E(2)- and P(4)-treated ovariectomized ewes; however, amounts of GM-CSF in pregnant ewes were 2-fold higher. Immunoreactive GM-CSF, examined by western blot, was detected in the culture medium from E(2)/P(4)-treated ovariectomized, cyclic and pregnant ewes. Luminal and glandular epithelia and stromal regions were determined to be sites of GM-CSF expression by immunohistochemistry and in situ hybridization techniques. Data indicate that combined E(2) and P(4) treatment of ovariectomized ewes is sufficient to restore GM-CSF expression to the level found in cyclic ewes; however, GM-CSF mRNA and protein in pregnant ewes is 2-fold greater than in ovariectomized or cyclic ewes. These data suggest that the conceptus, in addition to steroids, may play a role in the regulation of endometrial production of GM-CSF.     

Inhibin: Regulation of reproductive function and practical use in females

Inhibins are gonadal glycoprotein hormones selectively and potently inhibiting follicle‐stimulating hormone (FSH) secretion from the pituitary gland. Inhibins are produced mainly by the ovary and are purified from follicular fluid. Inhibins were shown to be produced in two forms through dimeric assembly of an α‐subunit and one of two closely related β‐subunits to form inhibin A (α‐βA) and inhibin B (α‐βB). Although inhibin subunits are expressed in various tissues, the gonads are the major source of circulating inhibins. While inhibins may act as a paracrine or autocrine factor in some tissues, their best understood roles are as endocrine regulators of pituitary FSH. In this review we focus our attention on more recent developments in inhibin research. We describe patterns of inhibin A and B secretion during the estrous cycle. We also review the immunization against inhibin α subunit as a practical method for superovulation. Superovulation has been induced successfully by passive or active immunization against the inhibin α‐subunit in several species such as mice, rats, hamsters, guinea pigs, cows, mares, ewes and goats. Furthermore, several studies have shown that oocytes superovulated with immunization against inhibin α‐subunit have the ability to develop normally, suggesting that inhibin immunization could be used as a practical method for superovulation in a wide range of animal species.     

Fasting influences steroidogenesis, vascular endothelial growth factor (VEGF) levels and mRNAs expression for VEGF, VEGF receptor type 2 (VEGFR-2), endothelin-1 (ET-1), endothelin receptor type A (ET-A) and endothelin converting enzyme-1 (ECE-1) in newly formed pig corpora lutea

This study was designed to verify whether fasting influences vascular endothelial growth factor (VEGF) production and VEGF, VEGF receptor-2 (VEGFR-2) as well as endothelin (ET) system members (endothelin converting enzyme-1, ECE-1; ET-1; endothelin receptor type A, ET-A) mRNA expression in pig corpora lutea; furthermore, we wanted to assess whether fasting affects steroidogenesis in luteal cells. Eight prepubertal gilts were induced to ovulate and were randomly assigned to two groups: (A) n = 4, normally fed; and (B) n = 4, fasted for 72 h starting 3 days after ovulation. At the end of fasting, ovaries were removed from all the animals and corpora lutea (CLs) were collected. VEGF and steroid levels in luteal tissue were determined by ELISA and RIA, respectively; VEGF, VEGFR-2, ET-1, ET-A and ECE-1 mRNAs expression was measured by real-time PCR. VEGF protein levels were similar in the two groups, while all steroid (progesterone, testosterone, estradiol 17beta) concentrations were significantly (P < 0.001) higher in CLs collected from fasted animals compared with those from normally fed gilts. VEGF, VEGFR-2, ET-1 and ECE-1 (but not ET-A) mRNA expression was significantly lower (P < 0.05) in fasted versus normally fed animals. The overall conclusion is that all the parameters studied are affected by feed restriction, but the mechanisms activated at luteal level are possibly not fully adequate to compensate for nutrient shortage.     

Endometrial inositol phosphate turnover in pigs is reduced during pregnancy and estradiol-induced pseudopregnancy

Three experiments were conducted to examine inositol phosphate (IP) turnover in response to treatments applied in vitro to endometrium from cyclic (CYC), pregnant (PREG) and estradiol-induced pseudopregnant (PSP) gilts. In Exp. 1, treatments (in 25 microliters .1 M NaHCO3) were 1) control (NaHCO3), 2) 125 ng oxytocin, 3) .25 micrograms prolactin, 4) 2.5 micrograms prolactin and 5) 5 micrograms pig conceptus secretory proteins (pCSP). Basal IP turnover on d 14 (estrus = d 0) for CYC was 3.9 to 5.0-fold greater than for PREG gilts and .6 to 1.1-fold greater than for PSP gilts (P less than .05). Oxytocin increased IP turnover 23 to 42% in CYC gilts (P less than .05), but not in PREG or PSP gilts. The treatment x reproductive status interaction (P less than .05) indicated that pCSP increased IP turnover 74 to 140% in PREG gilts but decreased it 18 to 22% in CYC and 17 to 50% in PSP gilts. In Exp. 2, treatments were applied in a 2 x 2 x 2 arrangement: 1) 0 or 125 ng oxytocin; 2) 0 or 2.5 micrograms prolactin and 3) 0 or 5 micrograms pCSP. Basal IP turnover on d 14 was 3.3 to 5.4-fold greater (P less than .05) in CYC than in PSP gilts and was affected by interaction (P less than .05) of pCSP and prolactin. Inositol phosphate turnover was increased by prolactin (12 to 22%) and by pCSP (7 to 34%) but, when combined, the stimulatory effects of each were eliminated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gene expression and hormonal regulation of adiponectin and its receptors in bovine mammary gland and mammary epithelial cells

Although the functions of adiponectin, a differentiated adipocyte‐derived hormone, in regulating glucose and fatty acid metabolism are regulated by two subtypes of adiponectin receptors (AdipoRs; AdipoR1 and AdipoR2), those in ruminants remain unclear. Therefore we examined the messenger RNA (mRNA) expression levels of adiponectin and its receptors in various bovine tissues and mammary glands among different lactation stages, and the effects of lactogenic hormones (insulin, dexamethasone and prolactin) and growth hormone (GH) on mRNA expression of the AdipoRs in cultured bovine mammary epithelial cells (BMEC). AdipoRs mRNAs were widely expressed in various bovine tissues, but adiponectin mRNA expression was significantly higher in adipose tissue than in other tissues. In the mammary gland, although adiponectin mRNA expression was significantly decreased at lactation, AdipoR1 mRNA expression was significantly higher at peak lactation than at the dry‐off stage. In BMEC, lactogenic hormones and GH upregulated AdipoR2 mRNA expression but did not change that of AdipoR1. In conclusion, adiponectin and its receptor mRNA were expressed in various bovine tissues and the adiponectin mRNA level was decreased during lactation. These results suggest that adiponectin and its receptors ware changed in mammary glands by lactation and that AdipoRs mRNA expression was regulated by different pathways in BMEC.     

Ontogeny of testicular inhibin and activin in ducks: An immunocytochemical analysis

The ontogeny of testicular inhibin/activin in ducks was investigated. Testicular localization of three inhibin/activin subunits (α, β_A and β_B) was determined in embryonic and newly hatched ducks from 12 days of incubation to 1 day of age, in immature ducks and in adult ducks. In the duck embryonic testis, positive α‐subunit immunostaining was first detected in the Leydig cells and Sertoli cells on day 15 of incubation, whereas β_A‐subunit and β_B‐subunit immunostaining were found in Sertoli cells and primary germ cells on day 18 of incubation. In 1 month old ducks, intense staining of α‐subunit was present in the seminiferous epithelium consistent with localization in Sertoli cells and primary germ cells, and the immunostaining of the β_A‐ and β_B‐subunit was also present in Sertoli cells and primary germ cells. Specific immunostaining with inhibin/activin α‐, β_A‐ and β_B‐subunits antisera occurred in Sertoli cells in the adult duck testes. In conclusion, it was shown that, in the duck testis, the majority of α‐, β_A‐ and β_B‐subunits are colocalized in Sertoli cells with a certain degree of staining in germ cells and the α‐subunit is present in Leydig cells of embryonic testes before day 18 of incubation. These results indicate that Sertoli cells and possibly germ cells in the embryonic testes of late stage of incubation and newly hatched ducks, immature ducks and mature ducks may produce bioactive inhibin dimers, inhibin A and inhibin B, as a possible regulator of follicle‐stimulating hormone secretion. Free inhibin/activin subunits and their dimers may also play an autocrine/paracrine role in the development of the testis and spermatogenesis. Furthermore, early onset of the α‐subunit in duck testes indicates that it may have an autocrine/paracrine effect on steroid hormones, which is important for sex differentiation.     

双拷贝抑制素基因免疫对大鼠卵泡发育、产仔及生殖激素的影响

将90只大鼠随机分为5组,分别注射10μg.100μL-1 pcISI(T1)、50μg.100μL-1 pcISI(T2)、100μg.100μL-1(T3)pcISI、100μg空载体pcMV-S(V)和100μL生理盐水(S),以探讨在不使用免疫佐剂的情况下,不同剂量的双拷贝抑制素pcISI基因免疫对大鼠卵泡发育、产仔和生殖激素的影响。结果表明,加强免疫能提高抗体P/N值,加强免疫后各剂量组平均抗体P/N值大于2,T3组抗体P/N值显著高于T1和T2组(P<0.05)。T3组成熟卵泡数显著高于对照组(P<0.05),且抗体阳性鼠成熟卵泡数比阴性鼠多12.45个(P<0.05)。除了T1组外,其他2个剂量组产仔数和胎盘数均高于对照组(P<0.05)。抗体阳性鼠胎盘数比阴性鼠多5.09个(P<0.05),产仔数比阴性鼠多5.39个(P<0.05)。抑制素pcISI基因免疫大鼠后促卵泡素(FSH)、雌二醇(E2)和孕酮(P4)含量均高于对照组,T3组的FSH含量与对照组差异显著(P<0.05),T3组的E2含量与对照组差异极显著(P<0.01),各剂量组P4含量与对照组差异均不显著(P>0.05)。这些结果说明,在没有免疫佐剂的前提下,双拷贝抑制素pcISI基因免疫可产生抗体,促进FSH分泌和卵泡发育,增加产仔数。本试验条件下100μg.100μL-1是最佳免疫剂量。     

抑制素主动免疫对大鼠生殖激素及卵巢发育的影响:Montanide和Freund’s佐剂效应比较

本研究采用新疆细毛羊抑制素成熟区序列重组融合蛋白(roINH)作为免疫原,以Montanide (MON)和Freund's (FA)作为佐剂,主动免疫SD大鼠,测定生殖激素及卵巢发育情况,评价佐剂效应.选用72只9～10周龄性成熟雌性SD大鼠,随机分为3组,分别皮下注射生理盐水(对照组)、roINH+ MON(MON组)和roINH+FA (FA组).各组大鼠每20 d免疫1次,连续免疫3次.结果,MON组产生的抗体滴度显著高于FA组(P＜0.05);与对照组相比,注射roINH+MON和roINH+FA均可极显著提高大鼠血清FSH平均含量(P＜0.01),显著提高P峰值(P＜0.05),而FSH及P平均含量及峰值在2个免疫组间无显著差异(P＞0.05);LH含量和峰值在2个试验组间无显著差异(P＞0.05); MON和FA组成熟卵泡数无显著差异(P＞0.05),但均显著高于对照组(P＜0.05);MON组脓包直径及炎症反应小于FA组.结果表明,应用roINH作为免疫原并配以MON或FA佐剂免疫大鼠均能取得较好的免疫效果,且MON佐剂炎症反应小于FA佐剂.