Physical-chemical and biological characterization of different preparations of equine chorionic gonadotropin

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Abstract

Ovarian stimulation with commercial preparations of equine chorionic gonadotropin (eCG) produces extremely variable responses in domestic animals, ranging from excessive stimulation to practically no stimulation, when applied on the basis of their declared unitage. This study was conducted to analyze four commercial preparations from different manufacturers via reversed-phase HPLC (RP-HPLC) in comparison with a reference preparation and an official International Standard from the World Health Organization. The peaks obtained by this qualitative and quantitative physical–chemical analysis were compared using an in vivo bioassay based on the ovarian weight gain of prepubertal female rats. The RP-HPLC data showed one or two peaks close to a main peak (t _R = 27.9 min), which were related to the in vivo bioactivity. Commercial preparations that have this altered peak showed very little or no in vivo activity, as demonstrated by rat ovarian weight and in peripubertal gilts induced to ovulate. Overall, these findings indicate that RP-HPLC can be a rapid and reliable tool to reveal changes in the physicochemical profile of commercial eCG that is apparently related to decreased biological activity of this hormone.

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The use of hormonal treatments to improve reproductive performance of anestrous beef cattle in tropical climates.

Aparecida Marques, Steven Reis, P Baruselli … (2004)

Most of the world's bovine herd is found in tropical regions. Bos indicus predominates, due to their adaptation to the climate and management conditions. Anestrous is the main factor that negatively affects reproductive performance of animals bred in these regions of the globe. Several factors affect postpartum anestrous, including suckling and maternal-offspring bond, and pre- and postpartum nutritional status. The short duration of estrus and the tendency to show estrus during the night, greatly affect the efficiency of artificial insemination (AI) programs in B. indicus cattle managed in tropical areas. Several restricted suckling or weaning procedures (temporary or permanent), and hormonal treatments have been used to induce ovulation and cyclicity in postpartum cows. Most hormonal treatments are based on progesterone/progestogen (P4) releasing devices associated with estradiol benzoate (EB), or a combination of GnRH/PGF(2alpha)/GnRH (Ovsynch). Treatments with GnRH/PGF(2alpha)/GnRH has presented inconsistent results, probably due to the variable number of cows in anestrous. Treatments using P4 devices and EB have resulted in apparently more consistent results than Ovsynch programs in B. indicus cattle; however, pregnancy rates are low in herds presenting high anestrous rates and moderate to low body condition. The addition of an eCG treatment at the time of device removal, which increased plasma progesterone concentrations and pregnancy rates in anestrous postpartum suckled B. indicus cows, may be useful to improve reproductive performance of beef cattle in tropical climates.

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Historical perspectives in gonadotrophin therapy.

Bruno Lunenfeld (2015)

The 20th century witnessed the steady development of knowledge about the reproductive process in animals and humans. These advances led to the identification of higher centres governing the dynamics of ovarian function and to the discovery of gonadotrophic hormones. As the mechanisms of action of these hormones became increasingly understood, they began to be used in the management of infertility during the early 1930s. Hormone extracts were originally prepared from animal pituitaries and pregnant mare serum, as well as from human pituitaries, placenta and urine, with pregnancies reported following their use in the late 1930s. This review traces the constant quest to reduce risks and improve safety and efficacy of hormone preparations for patients. It describes the complex path and perils leading to the pure hormone preparations that are available today, concluding with an optimistic glimpse towards the future. Small molecules that are orally active and specific are currently being investigated, some with the capacity to bypass many parts of the receptor conformation. Here lies the immediate future of this field, utilizing low-cost, small, defined molecules to stimulate follicle growth, ovulation and corpus luteum formation. Perhaps one day the classical gonadotrophins will no longer be required in clinical treatment.

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Equine chorionic gonadotropin.

S D Martinuk, Patrick B. Murphy (1991)

Cells from the chorionic girdle of the equine trophoblast invade the maternal endometrium at day 36 of gestation and become established as secretory elements known as the endometrial cups. These structures, which persist for 40-60 days, produce a gonadotropin which can be found in circulation until about day 130 of gestation. This glycoprotein has been identified in the horse and the donkey, with the former having received much better characterization. It consists of 2 noncovalently linked peptide chains; an alpha-subunit of 96 amino acids, which is common to that found in other horse glycoprotein hormones. The beta-subunit of 149 amino acids is identical to horse LH beta. Horse CG is the most heavily glycosylated of the known pituitary and placental glycoprotein hormones. The alpha-subunit has two and the beta-subunit one N-linked glycosylation site, and the beta-chain has in excess of four O-linked glycosylation sites. The N-linked glycans have some oligosaccharides that are not found on other glycoprotein hormones. The sialic component of glycosylation confers an exceptionally long half-life on CG compared to other glycoprotein hormones. Horse CG has LH-like activity in horse receptor and in vitro bioassays. In spite of the amino acid homology, it has lower LH activity than does horse LH. Its most intriguing, and as yet unexplained, characteristic is its pronounced FSH and LH activity in species other than the horse. Horse CG binds to FSH receptors of virtually all mammalian species, other than the horse, in which it has been tested and will produce biological effects peculiar to FSH. It has similar and potent interaction with LH receptors. The structural basis of this duality is not known but may be related to the region 90-110 of the beta-chain. Horse CG is believed to be constitutively expressed by the trophoblastic cells until the endometrial cups degenerate. The role of CG in equine gestation is not completely understood. It is believed to act as an LH-like hormone to induce supplementary ovulation and/or luteinization of follicles in the mare. It has not been established whether CG or the accessory corpora lutea are necessary for successful horse pregnancy. They may serve as a redundant system to assure that there is sufficient secretion of the primary corpus luteum to maintain pregnancy until the placenta assumes its role as the principal steroidogenic organ of gestation.

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Author and article information

Journal

Journal ID (nlm-ta): J Vet Sci

Journal ID (iso-abbrev): J. Vet. Sci

Journal ID (publisher-id): JVS

Title: Journal of Veterinary Science

Publisher: The Korean Society of Veterinary Science

ISSN (Print): 1229-845X

ISSN (Electronic): 1976-555X

Publication date (Print): December 2016

Publication date (Electronic): 20 December 2016

Volume: 17

Issue: 4

Pages: 459-466

Affiliations

[1 ]Agency for Agribusiness Technology of São Paulo, 13400-970 Piracicaba, Brazil.

[2 ]Biotechnology Department, IPEN-CNEN, Cidade Universitária Sao Paulo, 05508-000 São Paulo, Brazil.

Author notes

Corresponding author: Tel: +55-19-34215196; Fax:+55-19-34215196; rherrera@ 123456apta.sp.gov.br

Article

DOI: 10.4142/jvs.2016.17.4.459

PMC ID: 5204023

PubMed ID: 27297410

SO-VID: 93052ee4-6129-49d9-9e46-764f9f731e45

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

History

Date received : 25 September 2015

Date revision received : 17 March 2016

Date accepted : 12 May 2016

Funding

Funded by: FAPESP, CrossRef http://dx.doi.org/10.13039/501100001807;

Award ID: 2011/13096-0

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Physical-chemical and biological characterization of different preparations of equine chorionic gonadotropin

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Animal models of intrauterine growth restriction (IUGR)

Most cited references 32

The use of hormonal treatments to improve reproductive performance of anestrous beef cattle in tropical climates.

Historical perspectives in gonadotrophin therapy.

Equine chorionic gonadotropin.

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