Suppression of Progesterone-enhanced Hyperactivation in Hamster Spermatozoa by γ-aminobutyric Acid

It has been recently shown that mammalian spermatozoa were hyperactivated by steroids, amines and amino acids. In the present study, we investigated whether hyperactivation of hamster sperm is regulated by progesterone (P) and γ-aminobutyric acid (GABA). Although sperm hyperactivation was enhanced by P, GABA significantly suppressed P-enhanced hyperactivation in a dose-dependent manner. Suppression of P-enhanced hyperactivation by GABA was significantly inhibited by an antagonist of the GABA_A receptor (bicuculline). Moreover, P bound to the sperm head, and this binding was decreased by GABA. Because the concentrations of GABA and P change in association with the estrous cycle, these results suggest that GABA and P competitively regulate the enhancement of hyperactivation through the GABA_A receptor.     

Interleukin-1 receptor antagonist expression in the equine endometrium during the peri-implantation period

To identify factors involved in the establishment of pregnancy in the mare, endometrium was collected from day 13 (day 0 = day of ovulation) cyclic and day 13, 19, and 25 pregnant animals. From initial cDNA subtraction studies, interleukin-1 receptor antagonist (IL-1RN) mRNA was found as a candidate molecule expressed uniquely in the pregnant endometrium. Expression of IL-1RN mRNA was markedly increased in day 19 and 25 gravid endometrium. In situ hybridization analysis revealed that IL-1RN mRNA was localized to the glandular epithelium. Interleukin-1 receptor antagonist (IL-1RN) protein was found in the extracts of day 25 gravid endometrium and was immunochemically localized to the glandular epithelium/luminal cavity of the pregnant uterus. High concentrations of estradiol-17β (E₂) were detected in day 25 conceptuses. Concentrations of E₂ were higher in the gravid endometrial portion than in other endometrial regions. On the other hand, progesterone concentrations did not differ among endometrial samples analyzed. Furthermore, the expression of IL-1RN mRNA was up-regulated in endometrium culture samples treated with 10 ng/mL E₂ and 10 ng/mL progesterone. In the analysis of related gene expression, increased amounts of IL-1α and IL-6 mRNA were also found in the day 25 gravid endometrium; however, these expressions in endometrial culture samples were not up-regulated by the steroid treatment. These results indicate that expression of IL-1RN in the endometrium is likely regulated by E₂ and progesterone and suggest that IL-1RN regulates the degree of IL-1 signal transduction and thereby plays an important role in the establishment of equine pregnancy.     

国产LRH-A穴位注射治疗奶牛不孕症的研究

本研究系采用中西兽医结合的方法,首次应用国产LRH-A穴位注射后海穴、百会穴和催情穴(任选一穴)治疗因卵巢机能失调所造成的不孕症奶牛共177例,总有效率达73.6～100％,与肌肉注射疗法比较,提高疗效10.7％左右,用药量比肌肉注射节省2/3～4/5,取得了满意效果。在探索其治疗机理方面,测定了血浆中孕酮(P)和17β一雌二醇(E_2)的含量变化,提供了一定依据。     

Subclinical, chronic intramammary infection lowers steroid concentrations and gene expression in bovine preovulatory follicles

Various doses of estradiol-17β (E₂) were used in heifers to induce a pulse of 13,14-dihydro-15-keto-prostaglandin F_2α (PGFM). The effect of E₂ concentration on the prominence of PGFM pulses and the relationship between prominence and intrapulse concentration of progesterone (P₄), LH, and luteal blood flow were studied. A single dose of 0 (vehicle), 0.01, 0.05, or 0.1 mg of E₂ was given (n = six/group) 14 d after ovulation. Blood samples were collected, and luteal blood flow was evaluated hourly for 10 h after the treatment. The 0.05-mg dose increased and the 0.1-mg dose further increased the prominence of the induced PGFM pulse, compared with the 0.0-mg dose and the 0.01-mg dose. The PGFM pulses were subdivided into three different prominence categories (<50, 50 to 150, and >150 pg/mL at the peak). In the 50 to 150 category, P₄ concentration increased (P < 0.05) between −2 h and 0 h (0 h = peak of PGFM pulse). In the >150 category, P₄ decreased (P < 0.05) between −1 h and 0 h, LH increased (P < 0.05) at 1 h, and luteal blood flow apparently decreased (P < 0.05) at 2 h of the PGFM pulse. The novel results supported the following hypotheses: (1) an increase in E₂ concentration increases the prominence of a PGFM pulse, and (2) greater prominence of a PGFM pulse is associated with a greater transient intrapulse depression of P₄ at the peak of the PGFM pulse. In addition, the extent of the effect of prostaglandin F_2α on the increase in LH and changes in blood flow within the hours of a PGFM pulse was related positively to the prominence of the PGFM pulse.     

Effect of luteinizing hormone oscillations on progesterone concentrations based on treatment with a gonadotropin-releasing hormone antagonist in heifers

Close temporality has been reported between the episodic secretion of luteinizing hormone (LH) and progesterone (P4) during the midluteal phase and preceding the beginning of luteolysis in cattle. In the present studies, the relationship between LH and P4 was examined by blocking LH oscillations with the gonadotropin-releasing hormone (GnRH) antagonist, acyline. In a titration study, the minimal single acyline dose for blocking LH oscillations in heifers was 3 μg/kg. The main experiment compared LH and P4 concentrations and oscillations between a group treated with acyline on day 15 after ovulation (n = 8) and a control group (n = 4). Concentrations of P4 in blood samples collected every 8 h on days 13 to 18 indicated that acyline treatment did not alter the time that luteolysis began or the length of the luteolytic process. In blood samples collected every hour for 24 h beginning at the hour of treatment, acyline reduced the LH concentrations and blocked LH oscillations. The hourly LH means were 0.06 to 0.08 ng/mL, comparable to the mean concentration at the nadirs of LH oscillations in controls (0.07 ng/mL). During the hourly sampling, the GnRH antagonist produced the following P4 responses: (1) lower P4 concentrations, (2) fewer and reduced prominence of P4 oscillations, and (3) increased length and variability in the interval between the peaks of P4 oscillations. Results indicated that LH oscillations affect both the prominence and the rhythmicity of P4 oscillations during preluteolysis but not the onset and length of luteolysis.     

三种药物诱导罗氏沼虾产卵

使用孕酮、前列腺素、利血平三种药物，对罗氏沼虾注射以研究其催产效果。结果表明，三种药物以每属注射１μｇ催产效果最好，产卵率可达６５－８５％，比对比组（３５％）有明显提高，且孵出幼体与自然条件下孵出的幼体在生长上无明显差异。三种药物中，孕酮的效果最好。     

三种药物诱导罗氏沼虾产卵

使用孕酮、前列腺素、利血平三种药物，对罗氏沼虾注射以研究其催产效果。结果表明，三种药物以每属注射１μｇ催产效果最好，产卵率可达６５－８５％，比对比组（３５％）有明显提高，且孵出幼体与自然条件下孵出的幼体在生长上无明显差异。三种药物中，孕酮的效果最好。     

产后乏情奶牛的诱导发情研究

 本研究用奶牛初乳、新斯的明、孕激素和孕马血清促性腺激素(PMSG)处理产后乏情奶牛,测定处理后24头奶牛乳汁中孕酮(P₄)和17β-雌二醇(17β-E₂)水平变化。结果表明:初乳对产后乏情奶牛的诱导发情作用,可能与处理后乳汁17β-E₂/P₄增加有关;注射初乳时,配合用新斯的明能提高发情率;产后乏情奶牛,用初乳十新斯的明+LRH-A₂方法处理,可有效地诱导发情,且受胎率较高。     

植物甾醇对去卵巢KM小鼠血清生殖激素及乳腺组织孕激素受体的影响

本试验旨在研究植物甾醇对去卵巢小鼠血清激素及乳腺组织中孕激素受体的影响。50只雌性小鼠,随机选40只进行去卵巢手术,恢复7 d。分组如下：正常组、去卵巢对照组、植物甾醇低、中、高3个剂量组（每日灌胃20、80和320 mg/kg植物甾醇）。连续灌胃3周,第22天采集血样和乳腺组织,对小鼠血清中的雌二醇、孕酮和催乳素水平进行检测,对乳腺组织的孕激素受体基因表达进行荧光定量检测。结果表明,去卵巢对照组小鼠雌二醇水平显著低于正常组（P〈0.05）。植物甾醇组小鼠血清雌二醇水平持续升高,其中,高剂量组小鼠血清雌二醇水平与正常组最接近;与去卵巢对照组相比,去卵巢植物甾醇组小鼠血清孕酮水平均有提高,但差异不显著（P〉0.05）;与去卵巢对照组相比,去卵巢植物甾醇组小鼠催乳素水平先下降后上升,但他们之间无显著差异（P〉0.05）。与去卵巢对照组相比,植物甾醇各剂量组小鼠孕激素受体基因相对表达量呈上升趋势,低、中、高剂量组小鼠孕激素受体基因相对表达量分别是去卵巢对照组的1.05、1.13和2.78倍。植物甾醇可改善去卵巢小鼠内源激素不平衡的状况,促进乳腺组织PR基因的表达。     

The Activity and Localization of 3β-hydroxysteroid Dehydrogenase/Δ5-Δ4 Isomerase and Release of Androstenedione and Progesterone by Uterine Tissues During Early Pregnancy and the Estrous Cycle in Pigs

Steroid hormones are produced by the porcine uterus. We hypothesized that the uterus in pigs possesses active 3β-hydroxysteroid dehydrogenase/Δ⁵-Δ⁴ isomerase (3β-HSD) responsible for progesterone and androstenedione production, that uterine steroids may supplement the amount of steroid hormones produced by embryos and corpus luteum and that these steroids are necessary for maintenance of pregnancy. In this study, we examined 1) endometrial and myometrial expression of 3β-HSD mRNA, 2) uterine 3β-HSD protein activity and 3) in vitro production of A₄ and P₄ by uterine slices harvested from pigs on days 10 to 11, 12 to 13 and 15 to 16 of pregnancy and the estrous cycle. The expression of 3β-HSD and the presence and activity of 3β-HSD protein were different in the endometrium and the myometrium during the examined periods of pregnancy and the estrous cycle. Production of A₄ by the endometrium and myometrium was highest on days 12 to 13 of pregnancy and the estrous cycle. Endometrial secretion of P₄ did not differ in the course of early pregnancy and on the respective days of the estrous cycle. The gravid myometrium was the highest source of P₄ in pregnant pigs on days 12 to 13. The release of P₄ by the cyclic myometrium rose during the examined days of the estrous cycle. The steroidogenic activity of the uterus, as described in this study, may support early pregnancy or the luteal phase of the estrous cycle in pigs.