Home About us Contact
|
Home About us Contact | ||
|
|
||
Luteinizing Hormone (Luteinize + hormone)
Selected AbstractsFunctional reconstruction and synthetic mimicry of a conformational epitope using CLIPSÔ technology,JOURNAL OF MOLECULAR RECOGNITION, Issue 5 2007Peter Timmerman Abstract This paper describes immunization studies with CLIPS-constrained peptides covering only the major part (,3-loop) of a structurally complex antigenic site on human Follicle Stimulating Hormone , -subunit (FSH- ,). In cases where linear and SS-constrained peptides fail, the CLIPS-constrained peptides generate polyclonal antibodies with high neutralizing activity for hFSH. The sera were shown to be specific for hFSH over human Luteinizing Hormone (hLH) and human Chorionic Gonadotropin (hCG). ELISA-competition studies and circular dichroism (CD)-measurements illustrate clearly that activity of the peptides in antibody binding and generation relates directly to precise and appropriate fixation of the peptide conformation. Design of the CLIPS-peptides was entirely based on epitope mapping studies with two neutralizing anti-hFSH mAbs. Both mAbs were shown to bind to a conformational epitope located at the top of the ,1,,3-loop covering the amino acid sequences Y58 -P77 (,3-loop). The results described in this paper show that CLIPS-constrained peptides covering the Y58 -P77 sequence provide the minimally required structural entity necessary to generate reproducibly sera with high hFSH-neutralizing activity. Copyright © 2007 John Wiley & Sons, Ltd. [source] Neuropeptide Y (NPY) Delays the Oestrogen-Induced Luteinizing Hormone (LH) Surge in the Ovariectomized Ewe: Further Evidence That NPY has a Predominant Negative Effect on LH Secretion in the EweJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2003K. M. Estrada Abstract Studies in rats suggest that neuropeptide Y (NPY) plays a stimulatory role in the generation of the preovulatory luteinizing hormone (LH) surge, via the Y1 receptor. We have investigated this issue using the oestradiol benzoate (EB)-treated ovariectomized (OVX) ewe which is a model for the preovulatory LH surge. A Y1 receptor antagonist (BIBO3304) was infused (25 µg/h) into the third cerebral ventricle (III-V) from 2 h before EB injection for 24 h, and had no effect on the ensuing LH surge. Using in situ hybridization, we then examined expression of NPY mRNA in the arcuate nucleus during the luteal, follicular and oestrous phases of the oestrous cycle, and found that levels were greatest during the luteal phase. Thus, reduced NPY synthesis might be an integral factor in the events leading to the cyclic preovulatory LH surge. This was tested by infusion of NPY (25 µg/h) into the III-V (as above). The NPY infusion delayed the LH surge until the infusion was ceased. High levels of NPY expression during the luteal phase of the oestrous cycle may be caused by progesterone. Thus, we determined whether NPY cells possess progesterone receptors (PR) and whether progesterone treatment up-regulates NPY mRNA expression in the arcuate nucleus. Immunohistochemistry for NPY and PR was performed in OVX, oestrogen-treated ewes, but no NPY cells of the arcuate nucleus were seen to colocalize PR. In situ hybridization for NPY was performed in OVX and OVX ewes treated with progesterone. There was no significant effect of progesterone treatment on NPY mRNA expression in the arcuate nucleus. We conclude that chronically elevated levels of NPY block the preovulatory surge of gonadotropin-releasing hormone/LH secretion in sheep, but high levels of NPY mRNA expression in the luteal phase of the oestrous cycle cannot be explained by an action of progesterone. [source] Follicle Dynamics and its Relation with Plasma Concentrations of Progesterone, Luteinizing Hormone and Estradiol during the Egg-Laying Cycle in OstrichesREPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2009RGG Bronneberg Contents The aims of this study were (i) to describe the changes in the volume of large ovarian follicles (diameter >3 cm) during the 48 h egg laying cycle in farmed ostriches, and (ii) to quantify factors affecting the volume of the largest measured follicle and the plasma concentrations of progesterone (P4) and estradiol-17, (E2,). In eight egg-producing birds, which all ovulated during the study period, transcutaneous ultrasound scanning and blood sampling was performed at 3 h intervals. The average volume of the total number of visualized large follicles (Vtotal), the largest measured follicle (VF1), the second largest follicle (VF2) and of all follicles smaller than F2 (VF3,Fn) were each higher before than after oviposition. Vtotal, VF2 and VF3,Fn nearly doubled in the 24-h period before oviposition, while VF1 remained at an equal, rather high level until oviposition. Immediately after oviposition Vtotal, as well as the volume of the other follicle categories, decreased within 6 h, i.e. around the moment of ovulation. By performing statistical analysis on the basis of linear mixed-effects modelling, we quantified that: (i) VF1 was 13.2% higher before than after oviposition and increased with 6.5% when LH increased with 1 ng/ml; (ii) P4 levels were 93.2% higher before than after oviposition and increased with 43.1% for every 3 h closer to oviposition; when LH and E2, levels and VF1 increased with 1 ng/ml, 10 pg/ml and 10 ml, respectively, P4 increased with 116.6%, 50% and 6.1%; and (iii) E2, levels were 35.6% higher before than after oviposition, increased with 2.7% for every 3 h closer to oviposition and increased with 14.6% when LH increased with 1 ng/ml. It is concluded that during the egg-laying cycle in ostriches: (i) follicular mass, as estimated by the volume of visualized follicles larger than 3 cm, increases before and decreases after ovulation, and (ii) follicular dynamics and its accompanying endocrine plasma hormone profiles during the egg-laying cycle in ostriches follow a pattern similar to that in chickens. [source] Relationship Among Follicular Growth, Oestrus, Time of Ovulation, Endogenous Estradiol 17, and Luteinizing Hormone in Bos Indicus Cows After a Synchronization ProgramREPRODUCTION IN DOMESTIC ANIMALS, Issue 6 2007M Maquivar Contents To determine the pattern of follicular growth during oestrus and the relationship with estradiol and luteinizing hormone in ovulating and non-ovulating cows, three groups of (n = 10), thirty cyclic, Bos indicus cows were synchronized with CIDR, consecutively at 9-day intervals. Twenty-four hours after implant withdrawal, all cows synchronized in the same group with other cows displaying estrous behaviour after implant withdrawal were subjected to an intensive period of ultrasonographic observations (every 6 h for 120 h). Blood samples were taken to evaluate LH surge and 17- , estradiol. No differences were observed in follicular growth, ovulatory diameter and growth average in the three groups of synchronized cows. Cows ovulating (CO) had a better growth average in comparison with the group of cows not ovulating (CNO) (1.4 ± 0.7 mm vs 0.7 ± 0.5 mm, p < 0.06). The average time from estradiol release to LH surge was 39.3 ± 24.6 h. Differences were also observed between CO and CNO with respect to both the first concentration (27.7 ± 5.2 vs 58.6 ± 31.9, p < 0.004) and last concentration (79.3 ± 23.3 vs 99.2 ± 27.3, p < 0.05) of estradiol above 5 pg/ml. The average time from overt signs of oestrus to LH release was 8.4 ± 7.7 h. In the CNO, the increase in LH concentration was never above two SD from the basal average. In conclusion, there is a wide variability in follicular growth and ovulatory diameter between CO and CNO, which can affect the intervals of LH release, estradiol peak and ovulation. Yet, LH surge might be a good marker for timing ovulation in Zebu cows. [source] Pre-ovulatory Granulosa Cells of Infertile Women with Endometriosis are Less Sensitive to Luteinizing HormoneAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 2 2003David J. Cahill Cahill DJ, Harlow CR, Wardle PG. Pre-ovulatory granulosa cells of infertile women with endometriosis are less sensitive to luteinizing hormone. AJRI 2003; 49:66,69 © Blackwell Munksgaard, 2003 PROBLEM: Reduced fertilization rates in women with minor endometriosis may be the result of direct effects on the ovary or to primary dysfunction within the hypothalamic,pituitary,ovarian axis. This controlled study was designed to examine the steroidogenic potential of luteinized granulosa cells in women with minor endometriosis. METHOD OF STUDY: Granulosa cells were harvested at oocyte recovery and incubated for 3 hr in increasing concentrations of luteinizing hormone (LH). The dissociation constant for added concentrations of LH was computed (as Km LH) and the results were compared between women with endometriosis and controls. RESULTS: Women with minor endometriosis had a higher dissociation constant than women with tubal damage [Km 0.98 (0.58,9.24) versus 0.33 (0.28,0.72) ng/mL, P=0.019], indicating reduced sensitivity to LH. CONCLUSIONS: In women with endometriosis, granulosa cells were less sensitive to LH stimulation. This provides further evidence for primary ovarian dysfunction as a significant contributory cause of the associated subfertility. [source] | ||||||||||