Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls

The objective of the present study was to characterize the effects of nutrition on circulating concentrations of metabolic hormones, gonadotropins, and testosterone during sexual development in bulls. Nutrition regulated the hypothalamus-pituitary-testes axis through effects on the GnRH pulse generator in the hypothalamus and through direct effects on the testes. Pituitary function (gonadotropin secretion after GnRH challenge) was not affected by nutrition. However, nutrition affected LH pulse frequency and basal LH concentration during the early gonadotropin rise (10-26 weeks of age). There were close temporal associations between changes in insulin-like growth factor-I (IGF-I) concentrations and changes in LH pulse frequency, suggesting a role for IGF-I in regulating the early gonadotropin rise in bulls. The peripubertal increase in testosterone concentration was delayed in bulls with lesser serum IGF-I concentrations (low nutrition), suggesting a role for IGF-I in regulating Leydig cell function. Serum IGF-I concentrations accounted for 72 and 67% of the variation in scrotal circumference and paired-testes volume, respectively (at any given age), indicating that IGF-I may regulate testicular growth. Bulls with a more sustained elevated LH pulse frequency during the early gonadotropin rise (high nutrition) had greater testicular mass at 70 weeks of age relative to the control group (medium nutrition), despite no differences in metabolic hormone concentrations after 26 weeks of age. Therefore, gonadotropin-independent mechanism regulating testicular growth might be dependent on previous gonadotropin milieu.     

牦牛睾丸附睾LDH同工酶表达模式的研究

利用比色法和聚丙烯酰胺凝胶电泳技术对６、１２、１８、２４月龄半血野牦牛,横交半血野牦牛和家牦牛睾丸、附睾组织ＬＤＨ同工酶活性及谱带表达进行测析。结果表明,睾丸、附睾ＬＤＨ在相同月龄其表达模式不同,６月龄睾丸ＬＤＨ有四条酶谱,活性百分率依次（ＬＤＨ１〉ＬＤＨ３〉ＬＤＨ２〉ＬＤＨ４）附睾只有三条酶谱（ＬＤＨ１〉ＬＤＨ２〉ＬＤＨ３）;到１２、１８月龄时,睾丸ＬＤＨ有五条酶谱（ＬＤＨ１〉ＬＤＨ３〉ＬＤＨ４     

黄牛睾丸特异乳酸脱氢酶-C基因选择性剪接体的克隆与序列分析

采用RT-PCR方法从黄牛睾丸组织中克隆睾丸特异乳酸脱氢酶.C(LDH-C)基因的cDNA序列,结果发现2种Ldhc剪接体,根据Ldhc基因在进化上的保守性,参照普通牛Ldhc基因结构分析了黄牛Ldhc基因的选择性剪接体的结构,结果显示,剪接体存在外显子缺失:其中剪接体1缺失第7个外显子,剪接体2缺失第4和第7两个外显子.因为LDH-CA酶的NAD+结合结构域由Ldhc的外显子2-4编码,酶的活性中心由外显子4编码.所以剪接体1包含完整酶的NAD+结合结构域和酶的活性中心,剪接体2失去了大部分NAD+结合结构域和酶的活性中心.对黄牛睾丸组织和精子LDH同工酶的电泳分析未检测到潜在的Ldhc剪接体的表达,推测睾丸组织Ldhc选择性剪接的功能是调控该基因在睾丸中表达的方式之一.     

Chronic chlorpyrifos-induced oxidative changes in the testes and pituitary gland of Wistar rats: Ameliorative effects of vitamin C

Chlorpyrifos (CPF), a chlorinated organophosphate insecticide that is widely used in agriculture and public health, has been implicated in male reproductive toxicity. Apart from acetylcholinesterase inhibition, CPF has been shown to induce changes characteristic of oxidative stress. Therefore, the aim of the present study was to evaluate the effects of vitamin C on oxidative changes in the testes and pituitary gland of rats chronically exposed to CPF. Twenty adult male Wistar rats were divided into four groups of five animals each: Group I (S/oil) received soya oil (2 ml/kg); Group II (VC) was administered with vitamin C (100 mg/kg); Group III (CPF) was given CPF (10.6 mg/kg; ∼1/8th LD₅₀); Group IV (VC + CPF) was pretreated with vitamin C (100 mg/kg) and then given CPF (10.6 mg/kg), 30 min later. The regimens were administered orally by gavage once daily for 15 weeks. Thereafter, the rats were sacrificed and the testes and pituitary glands were evaluated for the concentration of malonaldehyde (MDA) and activities of superoxide dismutase (SOD) and catalase (CAT). The result shows that CPF increased MDA concentration and reduced activities of SOD and CAT, which were ameliorated by pretreatment with vitamin C.     

Towards a universal scale to assess sexual maturation and related life history traits in oviparous teleost fishes

The literature presents a confusing number of macroscopic maturation scales for fish gonads, varying from over-simplified scales comprising three to four stages to highly specific and relatively complicated nine-stage scales. The estimation of some important life history traits are dependent on a correct assessment and use of the gonadal maturation scales, and frequent mistakes have been made in many studies. The goal of this report is to provide a synthetic, relatively simple, yet precise maturation scale that works for most oviparous teleost fishes. The synthetic scale proposed here is based on the correspondence between key physiological and cytological processes of gamete development and corresponding modifications observed at the macroscopic level. It is based on previous and ongoing studies of several fish species pertaining to some of the most important African and Neotropical taxa, including Characiformes, Siluriformes, Osteoglossiformes and Perciformes. This scale should allow for standardized protocols of field studies and improve intra- and inter-specific comparisons of life history traits. Guidelines on the correct use of this scale to estimate these life history traits are provided.     

Sequential testicular and epididymal damage in Zebu bulls experimentally infected with Trypanosoma vivax

Six Zebu bulls aged between 31 and 34 months exhibiting good libido were used to study sequential testicular and epididymal damage in Trypanosoma vivax infection. Three bulls were infected with T. vivax, while the other three served as controls. All infected bulls became parasitaemic by day 5 post-infection and developed clinical trypanosomosis with rapidly developing anaemia. Representative bulls, one from each of the infected and control groups, were sacrificed on days 14, 28 and 56 post-infection. Testes and epididymides from these animals were studied histopathologically after processing and staining with haematoxylin and eosin (H and E). Testicular degeneration developed in all the infected bulls characterized by depletion of spermatogenic cells and destruction of interstitial tissue. The most severe testicular degeneration occurred in the bull that was sacrificed 56 days post-infection. Epididymal sperm reserves were 36%, 4% and 0%, respectively, in infected bulls that were sacrificed on days 14, 28 and 56 post-infection. The 0% epididymal sperm reserve may suggest complete cessation of spermatogenesis. It was concluded from this study that T. vivax infection of Zebu bulls could cause severe testicular and epididymal damage that may result in infertility or even sterility of the affected animals at early infection stages not previously thought.     

Bax and Bcl‐2 are involved in the apoptosis induced by local testicular heating in the boar testis

The aim of this study was to determine whether the effect of Bax and Bcl‐2 on the apoptosis of germ cells is caused by local testicular heating (42°C, 1 hr) in boar testis. The testes of three boars were exposed to 42°C for 1 hr. Three other boars were assigned as control (no heat treatment). After 6 hr of heat treatment, all boars were castrated and the testes were harvested. Immunohistochemical results showed that a redistribution of Bax was caused by heat stress, and Bcl‐2 was expressed in the cytoplasm and nucleus. Western blot analyses and quantitative real‐time polymerase chain reaction (QRT‐PCR) showed that the protein and mRNA levels of Bax and Bcl‐2 were increased after local testicular heating. The number of TUNEL‐positive cells was increased in the seminiferous tubules compared with the control after local testicular heating. These results suggested that local testicular heating induced the apoptosis of germ cells by regulating the Bax and Bcl‐2 protein levels.     

Apoptosis in adult rabbit testes during subacute endosulfan toxicity

Effects of endosulfan toxicity on testes and testosterone inhibition, and the effect of Vitamin C were studied in twenty-four male New Zealand White rabbits, divided into four groups, and given during 6 weeks either endosulfan alone, endosulfan and Vitamin C together, Vitamin C alone or the corn oil vehicle for endosulfan alone (control). Serum testosterone concentration decreased in response to endosulfan alone, but concurrent treatment with Vitamin C ameliorated the toxic effect on serum testosterone. The endosulfan regimen caused gross hyperemia and slight hemorrhage in some testes but histopathological findings of severe degeneration and necrosis in testes of some rabbits amplified the evidence of toxicity, as also did the severe apoptotic activity observed in Sertoli and Leydig cells. In contrast, concurrent treatment with Vitamin C significantly ameliorated other aspects of endosulfan toxicity. The findings relate to potential adverse effects of indiscriminate use of pesticides on human and animal fertility.     

己烯雌酚对成年仓鼠睾丸生精的影响

 探讨环境内分泌干扰物己烯雌酚(DES)对成年动物睾丸生精的影响。将DES皮下注射给成年仓鼠(剂量为1 mg·kg-1·d-1)，用光镜和电镜观察睾丸和生精细胞形态结构的变化，并用甲基绿-哌咯宁和脱氧核糖核酸末端转移酶介导的dUTP缺口末端标记法（TUNEL）检测生精细胞的凋亡。结果表明，DES处理后睾丸萎缩，曲精小管变细。曲精小管内的细胞排列紊乱，大量的精母细胞和精子细胞凋亡，少见长形精子细胞。电镜下，这些退化的精母和精子细胞的胞浆内有大量髓样或空泡状结构。DES诱发生精细胞凋亡是造成成年动物睾丸生精障碍的重要原因。     

外生殖器发育不全公鹅睾丸组织学及血浆睾酮水平研究

本试验以天府肉鹅母系 (四川白鹅 ,WW)、天府肉鹅父系 (川朗鹅 ,WL)、朗德鹅 (LL)为试验材料 ,研究不同品种公鹅和外生殖器官发育不同 (发育正常 :WLn、LLn ,发育异常 :WLa、LLa)公鹅睾丸的形态学、组织学特性、超微结构及血浆睾酮水平。结果表明 :公鹅睾丸重量、体积、曲细精管直径、生殖上皮高度、生殖细胞总数的数密度、精原细胞的数密度、精母细胞的数密度、精细胞的数密度、精子的数密度、间质细胞的数密度 ,WW公鹅显著大于WLn和LLn ;WLn大于LLn ,但差异不显著 ;WLn、LLn显著大于WLa和LLa ;WLa与LLa间差异不显著。公鹅睾丸超微结构可观察到各级生殖细胞数量WW多于WLn和LLn ;WLn、LLn多于WLa和LLa ;血浆睾酮水平 ,WW公鹅显著高于WLn和LLn ;WLn、LLn显著高于WLa和LLa ;WLn显著高于LLn ,WLa显著高于LLa。睾丸重量、体积及定量组织学指标与阴茎发育情况、血浆睾酮水平高低有关 ,因此可以通过观测公鹅阴茎发育情况、血浆睾酮水平 ,来对种公鹅进行选择。