NTF3基因与公猪繁殖性能相关性研究进展

神经营养因子3(neurotrophin 3,NTF3)是一种由靶细胞分泌合成并经神经突起逆向转运至胞体而发挥作用的小分子蛋白质,主要在神经系统的发育和生理功能维持中发挥重要作用。但近年来的研究表明,NTF3及其受体与睾丸的发育、成熟和精子发生过程等密切相关,同时,NTF3基因对公猪性机能发育、性成熟、生精调节等方面具有重要调控功能。本文简介NTF3的分子结构、分布、受体及作用机制、生物学功能,重点阐述NTF3基因的启动子、转录因子及其与公猪繁殖性能相关性的研究状况,以期为今后开展更多、更深入的科学研究提供参考。     

雌激素对睾丸发育及生精功能的影响

雌激素与睾丸的功能密切相关.人和哺乳动物体内雌激素的合成需芳香化酶(Ar)的参与,而雌激素与特异受体(ERα、ERβ)结合后才发挥生物学效应.在睾丸所有发育阶段,芳香化酶和雌激素受体几乎都有表达.在睾丸发育过程中,雌激素的缺乏对胎儿睾丸的发育有利.但对成年动物来说,大剂量的雌激素可以引起睾丸功能紊乱和生精障碍,而体外条件下小剂量的雌激素又能促进精原细胞的分裂、增生和分化,诱导精子发生和精子成熟,减少细胞凋亡.文章主要从睾丸内雌激素的来源、芳香化酶和雌激素受体的分布、雌激素对胎儿和新生儿睾丸发育以及对精子发生的影响这几个方面进行了综述.     

神经介素S的研究进展

神经介素S(NMS)是2005年发现的一种神经肽,含有36个氨基酸,与神经介素U结合共同的受体,在体内分布较为广泛,具有抑制摄食和饮水、调节生物节律、影响神经内分泌等作用。本文对NMS的生物学特性、受体、分布定位、作用机理和生理功能作了简要综述,并提出了一些可研究的领域。     

支配子宫的植物神经和肥大细胞与子宫免疫调节的关系

本文概述了近年来子宫的植物性神经支配、子宫肥大细胞（ＭＣ）的最新研究概况，阐述了植物性神经通过子宫肥大细胞对子宫免疫的影响及Ｐ物质对子宫免疫的调节。植物性神经可通过抑制子宫ＭＣ的增殖和组织胺释放来抑制子宫局部免疫水平，神经肽Ｐ物质能刺激子宫ＭＣ组织胺和细胞因子的释放来调节子宫免疫，但组织胺的释放与子宫的生殖状态有关。神经肽对ＭＣ功能的调节是免疫－神经－分分泌网络相互作用的一个侧面，深入研究神经肽对ＭＣ作用的机理，将有助于推动神经免疫的发展。     

甲状腺素对睾丸发育和功能的作用

甲状腺素几乎存在于所有的组织中,是对生长、发育、代谢起决定性作用的调控因子,并且改变甲状腺的状况能影响诸多器官和系统。尽管多年来睾丸一直被认为是与甲状腺素无关的器官,然而现在发现甲状腺素在睾丸发育和功能中起重要作用。大量的资料显示甲状腺如同影响精子形成一样影响着类固醇的形成,包括T3在睾丸支持细胞增殖和功能成熟方面的作用,以及它在出生后间质细胞分化和类固醇生成方面的作用。甲状腺素受体一直出现在发育期和成年期的睾丸细胞中,这暗示了T3可能直接作用于这些细胞来行使其功能。最近许多研究采用不同的方法和技术试图了解甲状腺素作用于睾丸细胞的潜在机制。现在的回顾旨在呈现一个甲状腺素在雄性生殖腺功能中的作用。     

禽类生长轴的发育及其对生长的调节

长期以来,科学家们对禽类胚胎的内分泌学作了大量的研究,主要集中在以下几个方面：１）内分泌腺的发育,包括各种激素分泌细胞的发生、分化和成熟;２）细胞内合成激素的细胞器的发育;３）内分泌细胞对促泌素应答能力的获得和靶器官受体的发育及受体后信号传导机制的建立;４）调控系统的发育,包括神经的发生,内分泌腺上神经的分布,以及神经内分泌系统的发育。本综述将重点讨论与禽类生长密切相关的下丘脑垂体生长轴的发育及其在胚胎和早期发育过程中的作用。１　概述动物的生长是一个复杂的过程,它由内因和外因共同决定的。外因…     

瘦素对动物能量代谢及繁殖性能的影响

瘦素是一种由脂肪细胞分泌,肥胖基因编码,并作用于下丘脑靶细胞上的瘦素受体的蛋白质,能影响人类和啮齿动物等许多动物的能量代谢、内分泌调节及繁殖性能.其相对分子质量为16 ku,共由167个氨基酸组成.瘦素进入血液循环后,作为神经内分泌激素,游离或与特异性运输蛋白质结合来调节诸多生理功能,如实现抑制食物、促进能量消耗、参与糖代谢、脂肪代谢、胰岛素分泌、甲状腺功能和神经内分泌调节等.研究表明,这些功能的实现可通过中枢神经系统作用,也可通过外周神经系统作用来实现.     

多巴胺及其受体的研究进展

多巴胺(dopamine，DA)是中枢神经系统中主要的神经递质，它参与运动、情感以及神经内分泌的调节，文中概述了多巴胺及其多巴胺受体的结构、功能以及作用机制的研究进展。     

成年大鼠睾丸去精索上神经对睾丸功能及肾上腺素能受体表达的影响

试验旨在研究精索上神经（superior spermatic nerve,SSN）对睾丸功能的影响,25只成年Wistar大鼠随机分为2组,试验组左右睾丸切除精索上神经,手术30 d后两组大鼠同时处死取样分析。结果显示,睾丸去精索上神经不影响睾丸指数的大小但使附睾尾精子数极显著降低（P＜0.01）,平均日增重显著增加（P＜0.05）。增殖细胞核抗原（PCNA）免疫组织化学染色结果显示,睾丸去精索上神经不影响曲细精管精原细胞和初级精母细胞的增殖,但影响曲细精管的形态和生殖细胞的规则排列。RT-PCR结果显示,睾丸去精索上神经明显上调β1AR mRNA的表达,下调β2AR mRNA的表达;另外切除精索上神经不影响睾丸3β-羟胆固醇脱氢酶（3β-HSD）mRNA表达,但显著抑制类固醇快速调节蛋白（StAR）、胆固醇侧链裂解酶（P450scc）mRNA表达（P＜0.05）。结果表明,支配睾丸的精索上神经通过调节肾上腺素能受体β1AR和β2AR的表达及StAR和P450scc影响睾丸睾酮的合成和精子的发生。     

CART肽对动物采食量和摄食行为的影响

CART肽作为新近发现的一种神经内分泌肽类物质,参与动物体内多种生物功能的调节.本文就其对动物采食量、摄食行为方面的影响,以及其调节途径作一简要综述.     

去精索上神经(SSN)和精索下神经(ISN)对大鼠睾丸发育和精子发生的影响

本试验旨在研究睾丸神经是否参与调控睾丸的发育和精子的发生过程。大鼠出生后10 d(Postnatal day10,PD10)切断睾丸精索上神经(Superior spermatic nerve,SSN)和精索下神经(Inferior spermatic nerve,ISN),然后分别在PD25和PD50时取样分析。结果显示:睾丸去神经不影响PD25时睾丸质量和睾丸大小(P<0.05),但使PD50时的睾丸质量和睾丸尺寸极显著减小,附睾尾精子数极显著降低(P<0.01)。增殖细胞核抗原(Proliferatingcell nuclear antigen,PCNA)免疫组织化学染色显示睾丸去神经不影响PD25时生殖细胞的增殖,但却影响PD50时生殖细胞的增殖。另外RT-PCR结果显示睾丸去神经明显降低PD25时睾丸3β-羟胆固醇脱氢酶1(3β-hydroxysterol dehydrogenase 1,3β-HSD1)mRNA的表达(P<0.05),并明显抑制PD50时3β-HSD1和雄激素结合蛋白(Androgen binding protein,ABP)mRNA表达(P<0.01)以及黄体生成素受体(Lute...     

Expression and localization of growth factors and their receptors in the mammalian testis. Part I: Fibroblast growth factors and insulin-like growth factors

It is now well established that normal development and function of testis are mediated by endocrine and paracrine pathways including hormones, growth factors and cytokines as well as by direct cell-to-cell contacts depending on tight, adhering and gap junctions. In the last two decades, several growth factors were identified in the testis of various mammalian species. Growth factors are shown to promote cell proliferation, regulate tissue differentiation, and modulate organogenesis. Interestingly, most of these peptides are expressed not only in the adult mammalian testis during spermatogenesis but also during testicular morphogenesis in prenatal and postnatal life. Our study was launched to provide an overview of the expression, localization, and putative physiological roles of growth factors and their receptors in the mammalian testis. The growth factors considered in this part of our review are fibroblast growth factors and insulin-like growth factors. These factors are found in testicular cells in prenatal, postnatal, and adult animals and are implicated in the regulation of important testicular activities including testicular cord morphogenesis, modulation of testicular hormone secretion and control of spermatogenesis.     

Function of contralateral testis after artificial unilateral cryptorchidism in dogs

The effects of a cryptorchid testis on the contralateral testis were investigated after artificially producing unilateral cryptorchidism in 8 beagle dogs. Bilateral testicular biopsy and collection of spermatic vein blood and peripheral vein blood were performed at the time of the operation to produce the cryptorchidism and 52 weeks later. The testicular tissue was used for histological examination by light microscopy and measurement of the testicular transferrin (Tf) concentration by enzyme immunoassay. Plasma testosterone (T), estradiol-17 beta (E2), and luteinizing hormone (LH) levels were measured by radioimmunoassay. Semen was collected weekly and its quality was examined. No spermatogenesis was observed in the cryptorchid testes at 52 weeks after the operation, and the number of germ cells in the contralateral testes had decreased but the number of Sertoli cells did not change. The Tf concentration in both testes had also decreased. The mean total number of sperm between 48 and 52 weeks after the operation (194 x 10(6)) was less than half the number before the operation (510 x 10(6)). Mean spermatic vein plasma T levels (51 ng/ml) in the cryptorchid testes 52 weeks after the cryptorchid operation were significantly lower than before the operation (91 ng/ml; P < 0.05). By contrast, spermatic vein plasma E2 levels (80 pg/ml) were significantly higher than the values before the operation (51 pg/ml P < 0.05). The peripheral plasma LH levels decreased. These findings indicate that a large quantity of E2 secreted by the cryptorchid testis inhibits the endocrine and spermatogenic functions of the contralateral testis in the dog. In particular, it is assumed that dysfunction of the contralateral testis is associated with Sertoli cell dysfunction suggested by the low Tf concentration.     

SPERMATIC GRANULOMA IN THE RAM: DIAGNOSIS BY ULTRASONOGRAPHY AND SEMEN CHARACTERISTICS

Ultrasonographic appearance of the testis and epididymis, and seminal characteristics, with regard to localization of spermatic granuloma were studied. In rams with spermatic granuloma (n = 9), diagnosed by clinical or ultrasonographic examinations before histopathological confirmation, localization of each lesion was recorded. Epididymal granulomas, caput and cauda, were seen as anechoic or hyperechoic areas with a distinct margin with or without a hyperechoic capsule. Granulomas in the testis were microscopic and, therefore, could not be detected by ultrasonography. Enlargement in the mediastinum testis was detected in all rams when there were granulomas in the caput. Heterogeneous testis parenchyma invaded by numerous hyperechoic foci, representing testicular degeneration, was associated with granulomas both in the epididymis and testis. Ultrasonographic appearance of the lesions did not differ with regard to season. Seminal characteristics varied between rams. It was concluded that ultrasonographic evaluation may give valuable information in the diagnosis of sperm granuloma in the ram.     

Absence of Sirtuin 1 impairs the testicular development in cattleyak by inactivating SF-1

Cattleyak, which are interspecific hybrids between cattle and yak, display much higher growth performances than yak. However, F1 male cattleyak are infertile due to defective testicular development. Sirtuin 1 (SIRT1) is a histone deacetylase that is essential for various biological processes, while the roles of testicular SIRT1 in yak and cattleyak are still poorly understood. Here, we found that SIRT1 was localized in various kinds of yak testicular cells except elongated spermatids while it was deficient in cattleyak testis. Further studies indicated that cattleyak testis exhibited decreased histone acetylation levels on H3 and H4. One of SIRT1 co-factors, steroidogenic factor-1 (SF-1), was lost in cattleyak testis at protein level. Expressions of several SF-1 target genes responsible for Sertoli cell development and steroidogenesis, including STAR, CYP11A1, CYP26B1, FDX1 and HSD3B, decreased significantly in cattleyak testis. In addition, SIRT1-mediated P53 acetylation was not responsible for the cell apoptosis in cattleyak testis. Taken together, our results suggested the deficiency of SIRT1 in yak testis caused inactivation of SF-1 and the impairment of testicular development. This research provides theoretical bases for understanding the mechanism of cattleyak sterility and gives new insights in revealing the roles of SIRT1 in regulating yak testicular development.     

Testicular seminoma associated with torsion of the spermatic cord in two cryptorchid stallions

Two adult horses had colic attributable to spermatic cord torsion and strangulation of abdominally retained neoplastic testes. Both horses had caudal abdominal soft tissue masses palpable per rectum. One horse was treated successfully by surgical removal of the testis, and the other was euthanatized without treatment. Histopathologic diagnosis of the involved testes was testicular seminoma. Spermatic cord torsion of an abdominally retained testis should be considered in the differential diagnosis of signs of abdominal pain in cryptorchid stallions, especially those with a palpable caudal abdominal mass.     

Unilateral testicular mastocytoma in a Peruvian Paso stallion

A 12‐year‐old Peruvian Paso stallion was examined for scrotal swelling and unilateral testicular enlargement of 4–6 weeks duration. Physical examination and ultrasonography of the scrotum revealed an enlarged, nonpainful right testis with a well encapsulated mass at the cranial‐medial aspect containing echodense flocculent material. Unilateral castration was performed and the testis, spermatic cord and vaginal tunic were submitted for histological examination, which revealed a mastocytoma with accompanying evidence of malignancy. Short‐term follow‐up examination did not reveal any evidence of abdominal metastasis and the stallion has since successfully achieved pregnancy in a small number of mares. Although considered rare, mast cell neoplasia should be considered as a differential diagnosis when unilateral testicular enlargement is encountered.