外源激素催乳对小牛泌乳的影响

利用外源激素刺激小牛泌乳的研究鲜有报道.研究对8月龄小牛进行外源激素注射,诱导小牛泌乳,并对催乳乳汁的乳脂、总蛋白、乳糖、干物质含量进行了分析.结果表明外源激素能有效刺激小牛泌乳,乳汁成分没有发生明显变化.这对快速鉴定转基因牛是否能生产活性蛋白具有一定意义.     

繁殖季节和非繁殖季节生殖激素处理空怀母马效果观察

研究旨在通过多种激素处理确定生殖激素对繁殖母马的处理效果。用不同激素分别对非繁殖季节(8—10月)的11匹空怀伊犁母马和繁殖季节(5—7月)的53匹空怀伊犁母马进行处理。在非繁殖季节,处理前后,用B-型超声波诊断仪每日扫描马两侧卵巢一次,记录卵泡数量,测量卵泡直径;在繁殖季节,通过直肠触摸判定马卵巢的卵泡发育状态。结果表明:母马对促卵泡素(FSH)、孕马血清(e CG)的处理不敏感,并且卵泡35 mm的马对人绒毛膜促性腺激素(h CG)的处理不敏感;氯前列烯醇(PG-cl)对马黄体有溶解功能,马垂体提取物(extracts of equine pituitary glands)可以显著增加大卵泡直径;对于排卵延迟马的治疗效果,人绒毛膜促性腺激素(h CG)作用促黄体素(LH)作用促排-3(Gn RH analogy)号作用。结论:氯前列烯醇(PG-cl)、马垂体提取物、人绒毛膜促性腺激素(h CG)、促黄体素(LH)和促排-3(Gn RH analogy)可以用于空怀母马,调控卵巢功能。     

比格犬脑垂体远侧部细胞的电镜观察

透射电镜观察表明,比格犬(Beagle)脑垂体远侧部实质中含有6种细胞,即生长激素细胞、催乳激素细胞、促甲状腺激素细胞、促性腺激素细胞、促肾上腺皮质激素细胞和滤泡—星形细胞,它们各有其超微结构特征。生长激素细胞呈圆形;胞核为圆形;分泌颗粒很多,圆形,直径约233～465nm,催乳激素细胞多呈不规则形;胞核为不规则形;分泌颗粒很多,圆形,直径约310～620nm。促甲状腺激素细胞呈圆形或卵圆形;胞核为圆形或卵圆形;分泌颗粒较少,直径约78～232nm。促肾上腺皮质激素细胞呈圆形或卵圆形;胞核为圆形或卵圆形;分泌颗粒较多,圆形,直径约155～310nm,分布于细胞周边。促性腺激素细胞呈圆形或椭圆形;胞核为圆形或椭圆形;分泌颗粒较少,呈圆形、卵圆形、杵状或不规则形,长径约155～434nm。滤泡—星形细胞呈星形或不规则形,有突起伸入相邻细胞之间;胞核为圆形或卵圆形;胞质内无分泌颗粒。     

繁殖季节蒙古母马垂体促性腺激素细胞分泌颗粒与血清FSH、LH浓度的相关性

研究证实，动物垂体FSH和LH呈脉冲式分泌，在接受适当刺激后开始释放，又能在接受另一些信息后调整分泌量或停止分泌，并且其血清FSH和LH含量随着年龄和生理状态的变化而变化上，而与垂体促性腺激素细胞数量的相关性极低；但是，在繁殖季节蒙古利亚矮种母马垂体促性腺激素细胞分泌颗粒的形态学特性是否与血清FSH和LH浓度变化存在相关性，目前尚未见有报道。为此，     

外源激素催乳对小牛泌乳的影响

<正>乳腺生物反应器由于具有其他生物反应器无可比拟的优势一直都受到各国科学家的重视,所以被广泛用于食用或药用蛋白的生产,尤其是牛乳腺生物反应器。但是众所周知,转基因牛生产     

泰山磐石散加减方对妊娠英纯血母马激素的调控及对马驹生长发育的影响

旨在研究复方中草药泰山磐石散(TSPSS)对妊娠不同阶段英纯血母马激素的调控及其对1月龄～6月龄马驹生长发育的影响.选取19匹英纯血妊娠母马,将其随机分为2组,试验组14匹,对照组5匹.妊娠期分为210、240、270、300 d4个阶段,试验组每个阶段连续饲喂5dTSPSS,对照组不喂药物.每次喂药前和喂药结束12 ...     

催乳激素对山羊脂肪酸合酶基因转录活性的影响

为探讨催乳激素对体外培养的山羊乳腺上皮细胞脂肪酸合酶（fatty acid synthase,FASN）基因转录活性的调控作用,试验分别用不同浓度的胰岛素（insulin,INS）、雌激素（estradiol,E₂）、催乳素（prolactin,PRL）及不同激素组合（INS+PRL、E₂+INS+PRL）处理山羊乳腺上皮细胞24 h,提取细胞总RNA,采用实时荧光定量PCR检测催乳激素对FASN基因mRNA表达水平的影响。细胞转染山羊FASN基因启动子报告基因载体,同样用不同浓度的胰岛素、雌激素、催乳素及激素组合处理24 h,利用双荧光素酶报告基因系统检测催乳激素对FASN基因启动子活性的影响。结果发现,用雌激素、催乳素处理山羊乳腺上皮细胞后,FASN基因启动子活性及mRNA水平极显著或显著上调（P<0.01;P<0.05）,雌激素浓度为10、100 μmol/L和催乳素浓度为0.1和1 μg/mL时效果最为明显,而胰岛素对FASN基因的启动子活性及mRNA水平没有显著影响（P>0.05）。用不同激素组合（INS+PRL、E₂+INS+PRL）处理细胞均能显著上调FASN基因启动子活性及mRNA表达水平（P<0.05）。结果表明,雌激素和催乳素能够调控FASN基因的转录活性,为进一步研究泌乳过程中FASN基因的分子调控机制提供理论依据。     

对41年来激素、乳腺生长和泌乳研究综述（上）

41年前当我即将毕业时，人们公认雌激素具有促进乳腺管道生长发育的功能；对于乳腺小叶泡发育来说，雌激素和孕酮是必要的成份，催乳素和生长激素也必不可少。对于实验室动物品种来说如果乳腺组织有发育完备的小叶泡系统，那么外源催乳素、糖皮质激素和雌激素就能够起到乳汁分泌，很难确定孕酮是否对这一过程有抑制作用。对于一些动物品种，催乳素和甲状腺素有催乳作用，而糖皮质激素却抑制泌乳。生长激素和胰岛素对泌乳的明确作用尚无定论，研究激素对奶牛乳腺发育及功能影响的文章很少。利用体外方法研究激素对乳腺的作用还不成熟，也很少有人定量研究激素对乳腺细胞数目以及牛乳成份的影响。在对血液激素水平、激素受体、生长因子、结合蛋白定量化方面以及激素的营养分配作用和激素对乳腺细胞的作用机制等方面还有待深入研究。总之，我们要避免过于局限在现有激素调节乳腺发育和泌乳功能的理解范围内，事实上泌乳的最大生理刺激是妊娠，而不是外源激素、生长因子、受体兴奋剂/拮抗物以及基因疗法等。     

Effects of photoperiod on the secretion of growth hormone and prolactin during nighttime in female goats

The aim of the present study was to clarify the effect of photoperiod on nighttime secretion of growth hormone (GH) in goats. Adult female goats were kept at 20°C with an 8 h or 16 h dark photoperiod, and secretory patterns of GH for 8 h in the dark period were examined with the profile of prolactin (PRL) secretion. GH was secreted in a pulsatile manner in the dark period. There were no significant differences in pulse frequency between the 8‐ and 16‐h dark photoperiods; however, pulse amplitude tended to be greater in the group with the 16‐h dark photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the same photoperiod (P < 0.05). PRL secretion increased quickly after lights off under both photoperiods. The PRL‐releasing responses were weaker in the 8‐h than 16‐h dark photoperiod. The secretory response to photoperiod was more obvious for PRL than GH. The present results show that a long dark photoperiod enhances the nighttime secretion of GH in female goats, although the response is not as obvious as that for PRL.     

Effects of hypothalamic dopamine on growth hormone‐releasing hormone‐induced growth hormone secretion and thyrotropin‐releasing hormone‐induced prolactin secretion in goats

The aim of the present study was to clarify the effects of hypothalamic dopamine (DA) on the secretion of growth hormone (GH) in goats. The GH‐releasing response to an intravenous (i.v.) injection of GH‐releasing hormone (GHRH, 0.25 μg/kg body weight (BW)) was examined after treatments to augment central DA using carbidopa (carbi, 1 mg/kg BW) and L‐dopa (1 mg/kg BW) in male and female goats under a 16‐h photoperiod (16 h light, 8 h dark) condition. GHRH significantly and rapidly stimulated the release of GH after its i.v. administration to goats (P < 0.05). The carbi and L‐dopa treatments completely suppressed GH‐releasing responses to GHRH in both male and female goats (P < 0.05). The prolactin (PRL)‐releasing response to an i.v. injection of thyrotropin‐releasing hormone (TRH, 1 μg/kg BW) was additionally examined in male goats in this study to confirm modifications to central DA concentrations. The treatments with carbi and L‐dopa significantly reduced TRH‐induced PRL release in goats (P < 0.05). These results demonstrated that hypothalamic DA was involved in the regulatory mechanisms of GH, as well as PRL secretion in goats.     

Ghrelin对莎能奶山羊垂体催乳素和生长激素mRNA表达的影响

垂体催乳素和生长激素对雌性哺乳动物泌乳的启动和维持以及乳腺的发育都发挥着重要的调节作用.为探讨ghrelin对奶畜泌乳的调节作用,10只泌乳期莎能奶山羊随机分为2组(试验组和对照组),每组5只.试验组羊静脉注射ghrelin(3.0μg/kg)3 h后检测垂体催乳素(Prolactin,PRL)和生长激素(Grouth hormone,GH)mRNA的表达,结果显示一定剂量的ghrelin对催乳素mRNA的表达具显著上调作用(P<0.01);对生长激素mRNA的表达也有显著促进作用(P<0.01).结果表明,ghrelin在垂体水平上对催乳素和生长激素mRNA的表达具有上调作用,提示ghrelin可能通过对这些激素的作用参与了对奶畜泌乳的调节.     

Effects of photoperiod on secretory patterns of growth hormone in adult male goats

The aim of the present study was to clarify the effect of photoperiod on secretory patterns of growth hormone (GH) in male goats. Adult male goats were kept at 20°C with an 8‐h or 16‐h light photoperiod, and secretory patterns of GH secretion were compared. In addition, plasma profiles of prolactin (PRL), insulin‐like growth factor‐I (IGF‐I) and testosterone (T) were also examined to characterize GH secretion. GH was secreted in a pulsatile manner. There was no significant difference in pulse frequency between the 8‐h and 16‐h photoperiods. However, GH pulse amplitude tended to be greater in the group with the 16‐h photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the 16‐h photoperiod (P < 0.05). The GH‐releasing response to GH releasing hormone was greater in the 16‐h than 8‐h photoperiod (P < 0.05). Plasma PRL and IGF‐I levels were higher in the 16‐h than 8‐h photoperiod (P < 0.05). In contrast, plasma T levels were lower in the 16‐h photoperiod (P < 0.05). These results show that a long light photoperiod enhances the secretion of GH as well as PRL and IGF‐I, but reduces plasma T concentrations in male goats.     

Comparative histomorphological study of endometrium in mares

Uterine acute post‐breeding inflammation is a physiological tissue response to the entry of exogenous elements, with persistent endometritis being the main pathology responsible for subfertility in the mare (Equus ferus caballus; Linnaeus, 1758). Mares can be classified as susceptible or resistant to endometritis according to their ability to remove intrauterine fluid within 48 hr after experimental inoculation. Endometrial biopsy is a technique that is commonly used to establish the degree of lesions that can affect the fertility of the mare. Endometrial histomorphometry is an objective and highly precise diagnostic method. The aim of this study was to compare, during oestrus, the endometrial histomorphometry of mares previously classified as susceptible (SM) or resistant (RM) to endometritis. Endometrial biopsies from 24 mares at the oestrus phase of the cycle were obtained. For the histomorphometric analysis, samples were histologically processed and subjected to routine Haematoxylin–Eosin staining. For the evaluation, the variables were considered as follows: 1‐Height of the lining and glandular epithelia (Lining SM = 15.9 μm vs. RM = 13.3 μm; Glandular SM = 15.0 μm vs. RM = 13.0 μm); 2‐Perpendicular diameters of endometrial glands (SM = 51.3 μm vs. RM = 44.8 μm); 3‐Number of endometrial glands per field (SM = 24.8 glands/field vs. RM = 20.5 glands/field). The results from this study suggest the existence of a relationship between the studied characteristics and the susceptibility/resistance to post‐breeding endometritis in mares. Thus, increased epithelial height, greater glandular density and greater development of the glands during oestrus would be related to a higher susceptibility to endometritis.     

Effects of leptin on the release of luteinizing hormone, growth hormone and prolactin from cultured bovine anterior pituitary cells

The effects of leptin on the release of luteinizing hormone (LH), growth hormone (GH) and prolactin (PRL) were studied in cultured bovine anterior pituitary (AP) cells in vitro. The AP cells were obtained from fully‐fed Japanese Black steers and were incubated for 3 h with 10^?13 to 10^?7 mol/L of leptin after incubating in Dulbecco's modified Eagle's Medium for 3 days. Leptin significantly increased the concentration of LH in the culture medium by 45 and 44% at doses of 10^?8 and 10^?7 mol/L, respectively, compared with the controls (P < 0.05). Leptin significantly increased the concentration of GH in the culture medium by 14 and 12% at doses of 10^?8 and 10^?7 mol/L, respectively (P < 0.05). Leptin also significantly increased the concentration of PRL in the culture medium by 26% compared with the controls at a dose of 10^?7 mol/L (P < 0.05). These results show that leptin stimulates the release of LH, GH and PRL by acting directly on bovine AP cells from fully‐fed steers.     

Sex steroid hormones do not enhance the direct stimulatory effect of kisspetin‐10 on the secretion of growth hormone from bovine anterior pituitary cells

The aims of the present study were to clarify the effect of kisspeptin10 (Kp10) on the secretion of growth hormone (GH) from bovine anterior pituitary (AP) cells, and evaluate the ability of sex steroid hormones to enhance the sensitivity of somatotrophic cells to Kp10. AP cells prepared from 8–11‐month‐old castrated calves were incubated for 12 h with estradiol (E₂, 10^?8 mol/L),progesterone (P₄, 10^?8 mol/L), testosterone (T, 10^?8 mol/L), or vehicle only (control), and then for 2 h with Kp10. The amount of GH released in the medium was measured by a time‐resolved fluoroimmunoassay. Kp10 (10^?6 or 10^?5 mol/L) significantly stimulated the secretion of GH from the AP cells regardless of steroid treatments (P < 0.05), and E₂, P₄, and T had no effect on this response. The GH‐releasing response to growth hormone‐releasing hormone (GHRH, 10^?8 mol/L) was significantly greater than that to Kp10 (P < 0.05). The present results suggest that Kp10 directly stimulates the release of GH from somatotrophic cells and sex steroid hormones do not enhance the sensitivity of these cells to Kp10. Furthermore, they suggest that the GH‐releasing effect of Kp10 is less potent than that of GHRH.     

Effects of leptin and leptin peptide amide on the release of luteinizing hormone, growth hormone and prolactin from cultured porcine anterior pituitary cells

The present study was carried out to determine whether leptin or leptin (116–130) peptide amide (lep (116–130)), an active fragment of the native protein in rats, is able to stimulate the release of luteinizing hormone (LH), growth hormone (GH) or prolactin (PRL) from cultured porcine anterior pituitary (AP) cells in vitro. The AP cells were obtained from 6 month‐old pigs and were incubated for 3 h with 10^?11?10^?7 mol/L leptin or lep (116–130) after being cultured in Dulbecco's modified Eagle's medium for 3–4 days. Leptin significantly increased the concentration of LH and GH in the culture medium at concentrations of 10^?8 and 10^?7 mol/L, respectively, compared with the controls (P < 0.05). Leptin did not increase the concentration of PRL in the culture medium. In contrast to these results, no effects of lep (116–130) on the release of LH, GH or PRL were seen in the cultured cells. These results suggest that leptin stimulates the release of LH and GH by acting directly on porcine AP cells, and that a fragment of leptin protein comprising amino acids 116–130 is not associated with the secretion of hormones in pigs.     

Progesterone inhibits prolactin and growth hormone release from fowl pituitary glands in vitro

After preincubation of anterior pituitary glands of broiler fowls for 20 h in either medium alone or medium containing progesterone, their responsiveness to hypothalamic stimulation and to thyrotrophin releasing hormone (TRH) was determined. Following exposure to progesterone the basal rate of release of prolactin was reduced in a concentration-related manner but basal growth hormone release was unaffected. Stimulation of the release of prolactin and growth hormone by both hypothalamic extract and TRH was reduced following incubation with progesterone, and the reduction of the prolactin response to TRH was related to progesterone concentration.