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81.
母猪超数排卵对胚胎发育和胚胎质量的影响 总被引:6,自引:0,他引:6
对湖北白猪青年母猪和经产母猪用孕马血清促性腺激素(PMSG)和人绒毛膜促性腺激素(HCG)进行超数排卵处理,发性后配种,手术采集胚工观察,实验发现,10IU/kg体重的PMSG能促进母猪的发情并显著提高青年母猪的排卵数,10IU/kg体重的PMSG对经产母猪的超排效果不明显。超数排卵影响胚胎的质量,自然发情母猪较超数排卵母猪排卵较快,且胚胎质量较好。 相似文献
82.
83.
John P. Chang Richard M. Jobin Anderson O. L. Wong 《Fish physiology and biochemistry》1993,11(1-6):25-33
Evidence for the involvement of Ca2+, protein kinase C, cAMP, and arachidonic acid metabolism in mediating gonadotropin (GTH) and growth hormone (GH) release
in the goldfish is reviewed. Models for the signal transduction pathways mediating GTH-releasing hormone (GnRH) and dopamine
actions on GTH and GH secretion are postulated. A novel hypothesis that two GnRHs which bind to the same receptor type activate
different transduction cascade in two different cell types (GTH vs. GH) as well as within the same cell type (GTH) is presented.
Résumé Cette revue présente les données expérimentales démontrant l'implication de Ca++, de la protéine kinase C et du métabolismes de l'acide arachidonique dans les mécanismes régulant la sécrétion des hormones gonadotrope (GTH) et de croissance (GH). Des modèles de signaux de transduction de l'action de la gonadolibérine (GnRH) et de la dopamine sur la sécrétion de GTH et de GH sont proposés. Les deux GnRHs existant chez le poisson rouge pourraient se lier au même type de récepteur et activer différentes voies de transduction dans deux différents types cellulaires (GTH vs. GH) ou dans un seul type (GTH).相似文献
84.
LI Zhongyang WANG Shengxiang QIANG Yuyun TIAN Tian ZHAO Baoyu WU Chenchen 《畜牧兽医学报》1956,51(12):3171-3180
Swainsonine (SW) can cause disorders of reproductive hormones. Gonadotropins are glycoprotein hormones, so they are regulated by N-glycosylation modifications. ɑ-mannosidase, a key enzyme that accelerates the processing of N-glycosylation modifications, can be inhibited by SW. So how does SW affect the structure of N-glycan and the secretion performance of reproductive hormone is unclear. Thus, this test was conducted by intraperitoneal injection of SW exposed mice to establish models of poisoning. The changes of N-glycan structure in their pituitary tissues were detected by MALDI-TOF-MS mass spectrometry; the activity of glycosylase, the level of reproductive hormone, the quantity of reproductive hormone receptors were analyzed. With the extension of injection time, the five composite glycosides of the pituitary glycoprotein in the poisoned group disappeared, and three hybrid glycosides were added. The activities of glycosyltransferase and glycosidase in the poisoned group were significantly decreased. There were further found that the expression levels of gonadotropin receptor, estradiol and progesterone receptor proteins in the poisoned group were significantly lower than those in the control group, and the secretion levels of reproductive hormones were also significantly decreased. SW can significantly inhibit the activity of N-glycan glycosylase and cause changes of normal N-glycan structure; it has a negative influence on the activities of gonadotropins and their receptors, causing the regulation of downstream steroid hormone secretion out of balance, and eventually, reproductive hormone regulation can be disrupted. 相似文献
85.
Xianzhong Wang Yan Sun Jianyun Wu Hongmei Pan Jiahua Zhang 《Frontiers of Agriculture in China》2007,1(3):334-338
It has previously been shown that Human Chorionic Gonadotropin (hCG) can stimulate steroidogenesis in Leydig cells. In the
present study, the mechanisms of hCG-stimulated steroidogenesis in Leydig cells of immaturated pigs were investigated. It
was found that both hCG and 8-Br-cAMP could enhance the expression level of both the Steroidogenic acute regulatory protein
(StAR) and mRNA, and increase the activity of extracellular signal-regulated kinase1/2 (ERK1/2) significantly depending on
stimulating time. However, the effect of 8-Br-cAMP was more significant than that of hCG. While appending the inhibitor of
Protein Kinase A (PKA) to Leydig cells in culture, the expression level of StAR protein, mRNA and the activity of ERK1/2 began
to drop significantly, but the level of StAR mRNA could still be detectable. While appending the inhibitor of MAPK (PD98059),
the expression level of StAR protein and mRNA declined significantly. These results infer that at the beginning of hCG stimulation,
hCG increases the level of StAR protein by cAMP-PKA. With prolonged stimulating time, hCG increases the level of StAR protein
through cAMP-PKA-ERK1/2.
Translated from Acta Veterinaria et Zootechnica Sinica, 2006, 37(11): 1154–1159 [译自: 畜牧兽医学报] 相似文献
86.
R. W. Schulz H. Paczoska-Eliasiewicz D. G. P. E. Satijn H. J. Th. Goos 《Fish physiology and biochemistry》1993,11(1-6):107-115
11-ketotestosterone (OT) is a typical androgen of male teleost fish, but information on the question if it is involved in the feedback regulation of pituitary gonadotropin II (GTH-II) secretion is controversial. We have therefore studied the effects of OT on gonadotropin releasing-hormone (GnRH) stimulated GTH-II secretion in male African catfish Clarias gariepinus). In vivo experiments were carried out with intact and castrated fish. OT plasma levels were increased by implantation of silastic capsules containing 11-ketoandrostenedione (OA) which is converted to OT in both intact and castrated fish. When intact males received OA- or blank-capsules, treatment with salmon gonadotropin releasing-hormone analogue (Des-Gly10-D-Arg6-sGnRH-NEt; 0.2 μg sGnRHa/kg body weight) elevated the plasma GTH-11 levels in both groups. However, the levels were about 2 times higher in blank- than in OA-implanted fish. When castrated fish received either blank-or OA-capsules, sGnRHa treatment led to plasma GTH levels significantly higher than in sham-operated fish. However, there was no difference between the blank- or OA-implanted castrates, though OA implantation led to a restoration of OT plasma levels. This suggests that replacement ofOT is insufficient to reverse castration-induced effects. In vitro experiments were carried out with pituitary tissue fragments using a static culture system. The tissue remained sensitive to sGnRHa (5 × 10?9M) for 4 days after the beginning of incubation. Preincubation of pituitary tissue for 24 hours with 25 ng OT/ml medium (80 nM) completely abolished the stimulatory effect of sGnRHa on GTH-II secretion. Tritiated OT was not metabolized by pituitary tissue during 6 hours of incubation. We conclude that 11-ketotestosterone, a quantitatively prominent and non-aromatizeable circulating androgen participates, at least in part by direct action on the pituitary, in the negative feedback regulation of GnRH-stimulated GTH-II secretion in male African catfish. 相似文献
87.
K. Mol N. Byamungu B. Cuisset Z. Yaron M. Ofir Ch. Mélard M. Castelli E. R. Kühn 《Fish physiology and biochemistry》1994,13(3):209-218
Triploidy as a result of thermal shock exposure of fertilized eggs decreases the growth rate ofOreochromis aureus as compared to their diploid controls, but this is due to the higher female ratio present in triploids (86%) and the lower
growth rate of females. When females and males are considered separately, the growth rate is not significantly different in
diploids and triploids. Since triploidy results in a malfunctioning steroidogenesis in females (mainly testosterone (T) and
17β-estradiol (E2)), but does not affect the growth rate, it is concluded that female gonadal steroids do not influence growth unless in pharmacological
concentrations. These low levels of gonadal steroids are generally accompanied by higher levels of gonadotropin (GtH), but
the difference is not always significant.
Despite their lower growth rate diploid females have higher plasma concentrations of growth hormone (GH) during several months
compared to the triploid females and diploid males. 3,5,3′-triiodo-L-thyronine (T3) levels, however, are comparable between diploid and triploid females (except for 1 month), but higher in diploid males in
4 of the 5 months studied. 11-ketotestosterone (11kT) is always higher in males. These results indicate that the higher growth
rate of males may be related to the high circulating levels of T3 and 11kT. 相似文献
88.
B. Breton T. Mikolajczyk C. Weill J. M. Danger H. Vaudry 《Fish physiology and biochemistry》1990,8(4):339-346
The action of neuropeptide Y (NPY) and gonadotropin releasing hormone (s-GnRH) have been compared on the release of gonadotropin
(GtH) by perifused rainbow trout pituitary glands sampled from freshly ovulated female rainbow trout. We have already demonstrated
that NPY stimulated the secretion of GtH in vitro.
The pituitary responses to s-GnRH and NPY were similar either after repeated 10 min infusions or a one hour prolonged application.
In both cases, after the first application, the pituitary did not responded to subsequent secretagogues stimulations, and
appeared to be desensitized. The stimulatory action of s-GnRH was partly inhibited (60%) by LH-RH antagonist (DpGlu1, DPhe2, DTrp3–6) LH-RH, which completely inhibited the response to NPY in perifused pituitary glands sampled from freshly ovulated females,
but did not modify the response of pituitaries taken from vitellogenic animals in which NPY induced a transient inhibition
of the GtH secretion. These results may indicate that the mode of action of NPY would differ between vitellogenic and matured
animals. NPY also stimulated the GtH secretion from perifused pituitary dispersed cells prepared from pituitaries taken from
freshly ovulated rainbow trout, indicating that NPY may act directly on the pituitary gonadotropic cells to stimulate GtH
secretion. 相似文献
89.
Koichi Okuzawa 《Fish physiology and biochemistry》2002,26(1):31-41
Puberty is the process by which animals acquire for the first time the ability to reproduce. In teleost fishes, an understanding
of the mechanism underlying pubertal development is important not only for basic science but also for aquaculture. In this
article, recent progress in several aspects of puberty in teleosts is reviewed; namely, pubertal changes in brain-pituitary-gonad
axis, factors controlling the timing of the onset of puberty, and artificial control of puberty. In addition, possible future
directions of study are suggested.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
90.
镉对鲤血清促性腺激素和生长激素的影响 总被引:3,自引:0,他引:3
采用CdCl2浸没法处理鲤,研究镉对鲤血清促性腺激素(GtH)和生长激素(GH)水平的影响,结果表明,较镐浓度镉(CdCl29mg/L)处理引起血清GtH水平降低,GH水平升高,提高水中钙浓度,能使由镉引起的GtH水平的降低恢得取正常水平,并对镉引起的GH水平升高起延迟作用,镉处理使鲤对LHRH-A刺激GtH分泌的反应性下降,提高水中钙浓度也不能恢复正常,实验结果提示,镉引起的GtH和GH的变化可 相似文献