褪黑素的生物合成及对繁殖性能的影响

褪黑素是一种广泛存在于动物体内的激素,不仅能够调节动物昼夜节律,还能够从多方面影响动物的繁殖性能,对于季节性繁殖动物,褪黑素根据日照时长的变化表现出抑制或促进繁殖性能的作用。对于幼年动物,褪黑素表现出抑制发情的作用,体成熟后则表现促进发情的作用。褪黑素主要通过下丘脑-垂体-性腺轴调控动物繁殖活动,除此之外,褪黑素还能够直接作用于生殖系统甚至早期胚胎,通过提高组织及细胞抗炎及抗氧化功能来改善动物繁殖性能。目前,褪黑素能够用于治疗精神疾病及炎症、促进畜禽繁殖和调节昼夜节律,是相关研究领域的热门话题。本文详细描述了褪黑素的生物合成以及分泌调控,并结合褪黑素的生理功能,阐述了对动物繁殖性能以及辅助生殖的影响。     

Night-time Melatonin Secretion and Seasonally Delayed Puberty in Gilts

This study was conducted to determine whether the seasonal delay in puberty in autumn is driven by individual differences in night-time melatonin secretion in domestic gilts at the attainment of puberty. A group of spring-born gilts (n = 30) were expected to reach puberty in autumn by the age of 7 months. Eighteen of these gilts were selected in pairs on the basis of matched days of birth. By the expected time, half of the animals showed oestrous symptoms (group CYCLING, n = 9) with the rest remaining silent (group SILENT, n = 9). Afterwards, all gilts were fitted with indwelling jugular catheters for frequent blood sampling. Blood samples were collected from all animals three times during the day followed by three times in the night at 2-h intervals for 48 h. The samples were analysed by a commercial radioimmunoassay (RIA). The results show a consistent 25-fold rise (on average) in night-time melatonin concentration in every animal sampled with group averages ranging from 0.28 +/- 0.04 to 0.37 +/- 0.06 pg/ml at day and from 10.20 +/- 2.16 to 10.67 +/- 0.05 pg/ml at night. Night-time group mean values between CYCLING and SILENT gilts did not differ significantly (10.26 +/- 0.67 and 10.38 +/- 0.94 for the CYCLING; 10.67 +/- 0.05 and 10.20 +/- 2.16 for the SILENT). When 10 pg/ml was used as a threshold value, six individuals did not reach it during the night (low responders). Two of these gilts were CYCLING and four were SILENT. In conclusion, the results presented imply no involvement of the level of night-time melatonin concentration in the seasonal delay of puberty in gilts.     

Intratesticular Morphometric, Cellular and Endocrine Changes Around the Pubertal Period in Dromedary Camels

We obtained the paired testes from 66 clinically healthy camels during two consecutive breeding seasons. Testicular tissues were examined for peripubertal changes in histological structure as well as spermatogenic and steroidogenic activities. Cellular sizes (length microm x width microm) increased linearly (P< 0.05) throughout the first three years of the animal's life for Leydig cells and between two and a half and five years of age for Sertoli cells. A clear increase in the percentage of tubules demonstrating primary and secondary spermatocytes occurred between less than one and five years and a cohort of elongated spermatids was produced in 3.5 +/- 0.2% tubules in males of two and a half years old; the appearance of spermatozoa in 3.1 +/- 0.3% tubules was evident six months later. The basal values for intratesticular and plasma concentrations of oestradiol-17 beta and testosterone respectively, were measured in all animals up to one and a half years for oestradiol-17 beta and three years for testosterone. Thereafter, both steroids increased markedly (P< 0.01) peaking to 269.5 +/-27.1 pg/g and 83.4 +/- 8.3 pg/mL at three years for oestradiol-17 beta and to 164.7 +/- 16.8 ng/g and 6.8 +/- 0.7 ng/mL at five years for testosterone. The results suggested that a steroid hormonal shift around four and a half to five years of age could demarcate the beginning of pubertal period which culminates with the production of the first ejaculum containing higher concentrations of spermatozoa by dromedary camels of six years old.     

褪黑素调控动物生殖内分泌的研究进展

褪黑素(MLT)是松果体分泌的一种神经内分泌激素,具有参与免疫反应、调节生命活动的节律性等多种生物学功能,并与生殖内分泌息息相关。目前对于褪黑素的研究主要集中在人类的癌症和植物等方面,而关于动物生殖内分泌的研究较少,深度较浅。研究表明,褪黑素可以调控动物下丘脑-垂体-性腺轴生殖相关激素的内分泌作用,抑制或促进促性腺激素释放激素(GnRH)、促卵泡素(FSH)、促黄体素(LH)、性腺激素的分泌。而在不同物种间,褪黑素作用效果却不同。论文综述了褪黑素对促性腺激素释放激素、促卵泡素、促黄体素、性腺激素以及其他与生殖相关激素的调控,为褪黑素调控动物生殖内分泌的的研究提供参考,以期对褪黑素在动物生殖调控中的作用更深入了解。     

褪黑激素受体基因的多态性及其与繁殖季节性之间关系的研究进展

褪黑激素通过与药理学特异的高素和性g-蛋白偶联受体相结合来发挥其生物学功能.本文介绍了褪黑激素受体基因的多态性分析及其与繁殖季节性之间的关系,并对牦牛该基因的研究做一展望.     

褪黑激素受体基因的多态性及其与繁殖季节性之间关系的研究进展

褪黑激素通过与药理学特异的高亲和性G-蛋白偶联受体相结合来发挥其生物学功能。本文介绍了褪黑激素受体基因的多态性分析及其与繁殖季节性之间的关系,并对牦牛该基因的研究做一展望。     

Administration of hCG 5 days after Breeding and Reproductive Performance in Nulliparous Dairy Goats

The objective of this study was to investigate the effect of hCG administration 5 days after breeding on plasma progesterone (P4) concentration and reproductive performance of oestrous-induced nulliparous dairy goats. A total of 59 nulliparous goats (36 Alpine and 23 Saanen) received intravaginal sponges with 60 mg medroxyprogesterone acetate for 9 days plus 200 IU equine chorionic gonadotrophin (eCG) and 22.5 microg d-cloprostenol 24 h before sponge removal. After detection of oestrus (day of oestrus = day 0) and breeding, 49 females were randomly assigned, according to the breed, into two treatments (T1 and T2). In T1 (n = 25) and T2 (n = 24), animals received intramuscular injection of 1 ml of saline solution (control) or 250 IU hCG, respectively, 5 days after breeding. Plasma P4 concentration (ng/ml) was determined from blood sampled on days 0, 5, 7, 13, 17, 21, 28 and 45 after breeding. Animals were scanned by transrectal ultrasound (5 MHz probe) on days 35 and 70 after breeding for detection of pregnancy. Plasma P4 concentration did not differ (p > 0.05) between treatments in all days, but it was increased (p < 0.05) in Saanen than in Alpine goats from days 13 to 45. Pregnancy and parturition rates, litter size and gestation period were similar (p > 0.05) to treatments and breeds. Results of this study indicate that human chorionic gonadotrophin (hCG) administration 5 days after breeding did not significantly alter reproductive performance in dairy nulliparous goats and that plasma P4 differed between Saanen and Alpine goats.     

光照对马岗鹅季节性繁殖活动和内分泌的调控

研究了光照对马岗鹅季节性繁殖活动和内分泌的调控。在整个试验期（2004.01.13-12.18）对照组接受自然光照,处理组接受人工控制的长短光照处理。在非繁殖期（4-7月份）,对照组公母鹅血浆PRL浓度升高,LH浓度和公鹅睾酮水平降低,鹅换羽;在繁殖期（8-3月份）,公母鹅血浆PRL水平下降,LH浓度和公鹅睾酮水平则上升。在处理组,延长光照均使公母鹅PRL浓度升高,LH浓度和公鹅睾酮水平降低,鹅群进入休产期并换羽;缩短光照则降低PRL水平,促进LH分泌和公鹅睾酮水平上升,鹅群进入繁殖期。整个试验阶段,两组中公鹅甲状腺素T3水平均无明显季节性变化,处理组和对照组母鹅平均产蛋48.8和26.3枚,前者比后者高85.6%。试验结果表明,长光照抑制,短光照促进马岗鹅繁殖活动,光照通过调节PRL和LH的分泌调控马岗鹅繁殖活动的季节性变化。     

光照和褪黑激素对非生绒期绒山羊激素分泌和绒毛生长的影响

为了研究光照和褪黑激素对绒山羊激素分泌和绒毛生长的影响。作者采用随机试验区组的方法,把36只绒山羊平均分成3组,分别进行长光照、短光照和自然光照处理,每组当中一半埋植褪黑素,分别检测血液激素水平和绒毛生长状况。结果表明,光照时间和埋植褪黑素显著影响绒山羊体内的激素分泌,长光照抑制褪黑素的分泌,短光照促进褪黑素的分泌,埋植褪黑素组的血浆褪黑素水平显著高于不埋植组。光照和褪黑素显著影响PRL、IGFI的分泌类型,并与绒山羊的绒毛生长有关,短光照或褪黑激素处理各组绒毛平均增加338.83 g;新生羊绒的长度、细度、强度等品质指标均符合纺织工业标准的要求。     

褪黑素对荷斯坦奶牛妊娠率及生殖激素的影响

试验旨在探明皮下注射褪黑素（MT）对荷斯坦奶牛配种妊娠率及血清生殖激素的影响。用计步器法确定自然发情的首次配种荷斯坦奶牛150头,对其中70头进行颈部皮下肌内注射褪黑素30 mg,12 h后进行人工输精;选择170头产后首次配种的荷斯坦奶牛进行同期排卵-定时输精处理,其中90头荷斯坦奶牛最后一次注射促性腺激素释放激素（gonadotropin-releasing hormone,GnRH）的同时进行颈部皮下肌内注射褪黑素30 mg,16 h后进行人工输精。在进行二次配种的荷斯坦奶牛中选择153只进行皮下注射褪黑素。荷斯坦奶牛输精后20~35 d进行妊娠检查,详细记录首次配种妊娠母牛头数、二次配种妊娠母牛头数、产犊数。选取同期排卵-定时输精的荷斯坦奶牛25头,皮下注射褪黑素8 h后用放射免疫法检测其血清中褪黑素、促卵泡素（FSH）、促黄体素（LH）、雌二醇（E₂）的含量及35 d妊检时妊娠母牛血清中孕酮（P₄）含量。结果显示,与自然发情和同期排卵对照组相比,其对应的皮下注射褪黑素组荷斯坦奶牛的妊娠率及产犊率均显著提高（P<0.05）;皮下注射褪黑素组的双犊率显著提高（P<0.05）,首次配种妊娠率和产犊率均显著提高（P<0.05）,二次配种妊娠率和产犊率均差异不显著（P>0.05）。血清激素检测结果表明,与对照组相比,皮下注射褪黑素组血清中褪黑素、LH、E₂含量均显著增加（P<0.05）;35 d妊检时,皮下注射褪黑素的妊娠母牛P₄含量显著增加（P<0.05）。本试验结果表明,皮下注射褪黑素能够提高荷斯坦奶牛的妊娠率、产犊率及血清中LH、E₂和P₄含量,说明皮下注射褪黑素能够促进卵母细胞成熟和排卵,并提高配种妊娠率。     

Influence of CRH and ACTH Administration on Endocrine Profile and Ovulation in Sows

Grouping of sows is a stressful event until the ranking is established. The purpose of this study was to simulate stress by repeated administration of porcine corticotropin releasing hormone (CRH) and adrenocorticotropic hormone (ACTH)/tetracosactide and to study its influence on endocrine profile and ovulation. Four multiparous sows were used and blood was collected every 2 h from the onset of pro-oestrus until 12 h after ovulation. The first oestrus after weaning was used to check ovulation and acclimate the sows to their environment. The second oestrus after weaning was used as control. At their third oestrus CRH (0.6 microg/kg) and at their fourth oestrus ACTH (5 microg/kg) were given every 4 h from onset of oestrus until ovulation. The total 'area under the curve' of cortisol was twofold larger in two of four sows during the CRH treatment period, and two- to fourfold larger (p < or = 0.05) during the ACTH treatment period, compared with the corresponding control period. In three sows, there was no clear effect of either CRH or ACTH on the levels of oestradiol 17beta, luteinizing hormone (LH) or on the timing of ovulation. One sow was different in all hormonal patterns and also in the timing of ovulation. In all four sows, ACTH treatment lowered the baseline level of prostaglandin F(2 alpha)-metabolite. Therefore, we conclude that stage of the oestrous cycle seems to be of importance when investigating the influence of exogenous administration of CRH/ACTH on hormonal pattern and ovulation time in the sow.     

雌酮主动免疫对美利奴母羊发情产羔和生殖内分泌的影响

20头母羊在配种季节开始前6周和3周,用雌酮免疫原免疫2次(E组),13头不作处理为对照(C组)。免疫不影响母羊正常发情,可使母羊产羔率由115.38％提高到156.25％,发情当天的LH水平显著提高(3.06±0.61对1.93±0.88miu/ml);发情周期黄体期的孕酮水平亦增加,周期12天时差异显著(9.31±3.53对3.71±0.92ng/ml);整个发情周期内E组的睾酮水平显著高于C组,而17β-雌二醇水平两组间无差异。     

虎斑颈槽蛇的生殖生态学探讨

虎斑颈槽蛇雄性睾丸于５ 月达最大值,随后逐渐减小,到冬眠期至最轻。雌性产卵期为６ ～７ 月中旬,卵生,一年一次性产卵６ ～２２ 枚,孵化期为４１ ～４３ ｄ。本文较详细观察和描述了１１ ～１６ 期胎蛇的外部形态特征和发育时序。     

Bovine Normal and Abnormal Reproductive and Endocrine Functions during the Postpartum Period: A Review

The results of numerous studies on postpartum uterine involution, ovarian activity and endocrinological changes before, during and after normal and abnormal parturitions, have been reviewed in this article. Most studies have shown that abnormal parturition is the main factor which delays completion of uterine involution and occurrence of the first estrous cycle post partum. The reviewed reports also indicated that any interference (corticosteroid injection, overiectomy, etc.) with normal synchronized hormonal changes of parturition can increase the incidence of retained fetal membrane. Reports on the use of hormonal treatments and their effects on the elimination of bacterial infection, rate of uterine involution and the resumption of ovulation activity are conflicting. It is suggested that the use of natural substances such as lipopolysaccharide of E. coli, serum or hyperimmune serum, extracts of poly morphonuclear leucocytes and/or macrophage-granulocyte Colony Stimulating Factor as treatments of postpartum uterine infection may play an important role in the completion of uterine involution and the commencement of estrous cycle .     

母牦牛的繁殖特性与人工授精

牦牛是青藏高原特有的遗传资源,是高寒牧区的基本生产生活资料。牦牛繁殖是牦牛生产中的关键环节,深入了解母牦牛的繁殖特性是实施牦牛繁殖调控的基础。本文从初情期、性成熟、发情、妊娠期、分娩、繁殖力等方面综述了牦牛的繁殖特性,并探析了提高牦牛人工授精效率的技术措施,旨在为牦牛品种改良提供技术参考。     

菟丝子总黄酮对生殖内分泌调节的研究进展

近年来,菟丝子在临床上经常用于治疗生殖内分泌类疾病,且作用效果显著。菟丝子是旋花科植物,具有毒副作用小、无耐药性、富含多种营养物质、成本低廉等优点,是纯天然的药用植物。菟丝子总黄酮是菟丝子中最有效的成分,具有止泻、滋补肝肾、益精壮阳和安胎等功效,不仅对雌雄动物生殖内分泌活动有调节作用,还对免疫、心脑血管等多个系统具有药理作用。动物的生殖内分泌活动主要由下丘脑-垂体-性腺轴调控,包括生殖激素的分泌以及精子的发生、卵泡的发育,对动物生殖繁育起着重要作用。绝大多数动物的生殖内分泌疾病都与下丘脑-垂体-性腺轴所调节的生殖激素以及生殖器官的发育状态有关,生殖激素可以通过直接或间接作用引起下丘脑-垂体-性腺轴功能性障碍疾病。鉴于目前经济动物禁用激素类药物,因此迫切需要研究安全有效低毒的中草药的作用及其机理,为其广泛应用奠定基础。文章介绍了菟丝子总黄酮主要的药理作用,并详细阐述了菟丝子总黄酮对下丘脑-垂体-性腺轴不同级内分泌活动的调控作用,为今后进一步研究菟丝子总黄酮对下丘脑-垂体-性腺轴调控的作用靶点和作用机理提供参考。     

Effect of Testosterone Administration and Spiking on Reproductive Success of Broiler Breeder Flocks

Age negatively affects reproductive success of broiler breeder flocks. One of the main hormones involved in the change of fertility with the age is testosterone (TT). The introduction of young males at later production stages of broiler flocks is known as spiking and is expected to reduce the fertility decline with age. The aim of this study was to determine the effect of injection of different levels of TT and the effect of spiking on reproductive fitness of broiler breeder flocks. Two experiments were conducted on Ross 308 breeder flocks for 10 weeks (41–50 weeks of age). The experiment 1 included a control and three treatments corresponding to three doses of TT (0.1, 0.2 and 0.3 cc), while the experiment 2 included a control and one treatment corresponding to spiking. The lower dose of TT (0.1 cc) and the spiking clearly slowed down the decline in hatchability. Therefore, either the external administration of TT to the males when the natural concentration of TT starts to decline or spiking the breeder flock with young roosters could contribute to improve reproductive success in later stages of the production cycle in broiler breeder flocks.