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Gautier C, Aurich J, Melchert M, Wagner LH, Kaps M, Okada CTC, Ertl R, Walter I, Aurich C. Endocrine changes induced by GnRH immunisation and subsequent early re-stimulation of testicular function with a GnRH agonist in stallions. Reprod Fertil Dev 2024; 36:RD23185. [PMID: 38237640 DOI: 10.1071/rd23185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/23/2023] [Indexed: 04/11/2024] Open
Abstract
CONTEXT Resumption of testicular function after gonadotrophin-releasing hormone (GnRH) immunisation varies among individual animals and some stallions regain fertility only after a prolonged time. AIMS This study evaluated endocrine effects of GnRH immunisation and early subsequent re-stimulation with a GnRH agonist. We hypothesised that GnRH agonist treatment advances resumption of normal endocrine function in GnRH-vaccinated stallions. METHODS Shetland stallions were assigned to an experimental and a control group (n =6 each). Experimental stallions were GnRH-immunised twice, 4weeks apart. Each experimental stallion was hemicastrated together with an age-matched control animal when testosterone concentration decreased below 0.3ng/mL. Three weeks later, daily treatment with the GnRH agonist buserelin was initiated (4μg/day for 4weeks followed by 8μg/day). The remaining testicle was removed when testosterone concentration exceeded 0.5ng/mL in vaccinated stallions. Blood was collected for LH, FSH, oestradiol and anti-müllerian hormone (AMH) analyses, and testicular and epididymal tissue were conserved for real-time qPCR and histology. KEY RESULTS GnRH vaccination reduced blood concentrations of LH and FSH, with a structural deterioration of testicular tissue and disruption of spermatogenesis. Daily buserelin treatment for approximately 60days partially restored gonadotropin secretion and induced a recovery of the functional organisation of the testicular tissue with effective spermatogenesis. CONCLUSIONS Endocrine testicular function can be restored in GnRH-vaccinated stallions by daily low-dose buserelin treatment. The buserelin treatment protocol may potentially be improved regarding the dose, interval and duration. IMPLICATIONS Daily buserelin treatment can be recommended for treatment of GnRH-vaccinated stallions with prolonged inhibition of testicular function.
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Affiliation(s)
- Camille Gautier
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Jörg Aurich
- Obstetrics, Gynecology and Andrology, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Maria Melchert
- Obstetrics, Gynecology and Andrology, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Lisa-Hélène Wagner
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Martim Kaps
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Carolina T C Okada
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Reinhard Ertl
- VetCore Facility for Research, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Ingrid Walter
- VetCore Facility for Research, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria; and Institute of Morphology, Department of Pathobiology, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
| | - Christine Aurich
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Veterinärplatz 1, Vienna 1210, Austria
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Birrell JR, Schulman ML, Botha AE, Ganswindt A, Fosgate GT, Bertschinger HJ. Vaccination against GnRH as a prelude to surgical castration of horses. Equine Vet J 2020; 53:1141-1149. [PMID: 33354803 DOI: 10.1111/evj.13411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 11/12/2020] [Accepted: 12/13/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND Surgical castration is one of the most frequently performed surgeries in horses and is associated with various post-surgical complications ranging in severity. OBJECTIVES We investigated the effects of administering an anti-GnRH vaccine to colts for reduction of testis size on the incidence of complications associated with their subsequent surgical castration. STUDY DESIGN Randomised open controlled trial. METHODS Nineteen colts were randomly assigned to one of the three groups. Treatment Groups V1-57 and V2-100 received two treatments of Improvac® (Zoetis, South Africa) before their castration in the field on either Day 57 or Day 100 following first treatment, respectively. Controls similarly received placebo treatments followed by castration on Day 57. Serial measurements of testicular dimensions and serum samples for measuring serum testosterone concentrations (STCs) and anti-GnRH antibody titres (ABTs) were obtained pre- and post-vaccination and on the day of castration. Clinical data recorded for 10 days determined post-surgical complications. RESULTS All vaccinated colts showed a baseline STC concentration at castration with a strong ABT response. Mean testicular volume of Groups V1-57 and V2-100 reduced by 49.7% and 30.8%, respectively, on Day 57 and this further reduced in Group V2-100 by 63.9% at castration on Day 100. Testis size was significantly correlated with post-surgical preputial (P = 0.001) and scrotal (P = 0.025) swelling. MAIN LIMITATIONS A study population of young light horse breed colts and a relatively small sample size limited this pilot study. CONCLUSIONS Administering two doses of Improvac® in colts 28 days apart prior to castration effectively reduced their testicular volumes with associated significant post-surgical improvement in both the incidence and degree of local swelling. These results may inform mitigation of potential post-surgical complications associated with castration in the field.
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Affiliation(s)
- John R Birrell
- Division Visible Policing, Veterinary Science Services, Arcadia, South Africa
| | - Martin L Schulman
- Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Alma E Botha
- Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - André Ganswindt
- Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.,Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - Geoffrey T Fosgate
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Henk J Bertschinger
- Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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Yao Z, Si W, Tian W, Ye J, Zhu R, Li X, Ji S, Zheng Q, Liu Y, Fang F. Effect of active immunization using a novel GnRH vaccine on reproductive function in rats. Theriogenology 2018; 111:1-8. [PMID: 29407422 DOI: 10.1016/j.theriogenology.2018.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 01/13/2018] [Accepted: 01/18/2018] [Indexed: 11/29/2022]
Abstract
To investigate the effect of gonadotropin-releasing hormone 2-multiple antigen peptide (GnRH2-MAP) on reproductive function. In our study, 20-day-old male rats (n = 90) were randomly allocated to one of three treatment groups: GnRH2-MAP immunization, GnRH2 immunization, and non-immunized control groups. The immunized animals were administered three doses of GnRH2-MAP or GnRH2 vaccines from 0 to 6 weeks at 2-week intervals. The control group only received oil adjuvant. Blood and right testis samples were collected, and the left testis was weighed and its volume was measured at 0, 2, 4, 6, 8, 10 and 12 weeks after the first immunization. The serum antibody titer and testosterone concentration were determined by ELISA, and the right testis samples were collected for histological analysis. The results revealed that the serum of vaccinated rats elicited a significantly higher antibody titer and a lower T concentration compared with the control group two weeks after the first immunization (P < 0.05), but the highest antibody titer and lowest T concentration were found in animals treated with GnRH2-MAP (P < 0.05). The second immunization resulted in a significant decrease in testicular weight and volume (P < 0.05) in both immunized groups compared to the control, but these values were significantly lower in the GnRH2-MAP group than in the GnRH2 group. Furthermore, seminiferous tubules revealed more significant atrophy in the GnRH2-MAP group than in the GnRH2 group, and no sperm were observed in rats of the GnRH2-MAP group. Thus, GnRH2-MAP may be an effective antigen and a potential immunocastration vaccine with higher effectiveness.
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Affiliation(s)
- Zhiqiu Yao
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Wenyu Si
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Weiguo Tian
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Jing Ye
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Rongfei Zhu
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Xiumei Li
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Shichun Ji
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Qianqian Zheng
- Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Ya Liu
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China
| | - Fugui Fang
- Anhui Provincial Key Laboratory of Genetic Resources Protection and Biological Breeding in Local Livestock and Poultry, 130 Changjiang West Road, Hefei, Anhui 230036, China; Department of Animal Veterinary Science, College of Animal Sciences and Technology, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui 230036, China.
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Su S, Fang F, Liu Y, Li Y, Ren C, Zhang Y, Zhang X. The compensatory expression of reproductive hormone receptors in the thymus of the male rat following active immunization against GnRH. Gen Comp Endocrinol 2013; 185:57-66. [PMID: 23395683 DOI: 10.1016/j.ygcen.2013.01.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 01/18/2013] [Accepted: 01/19/2013] [Indexed: 11/15/2022]
Abstract
To determine whether hormone-receptor signaling pathways in the thymus are altered by active immunization against gonadotrophin-releasing hormone I (GnRH), 3-week-old Sprague-Dawley male rats received GnRH-tandem-OVA peptides (200 μg/ml), and the effects were compared to a control group. Serum testosterone, LH and FSH concentrations were markedly reduced, with severe testicular atrophy, compared to controls, demonstrating effective blockade of the pituitary-gonadal axis. The reduction in LH and FSH concentrations in the thymus of immunized animals was lower than that observed in the serum, where a significant difference (P<0.001) in concentration was observed between both groups. Concentrations of GnRH were increased in the thymus of immunized rats. In thymic tissue, GnRHR, FSHR and LHR demonstrated stronger immunostaining, and AR weaker staining, in the immunized group compared to controls. Reproductive hormone receptor mRNA expression was consistent with protein variations in the immunized thymus. Compared to controls, GnRHR gene levels were significantly increased (P<0.05), however, AR mRNA expression were greatly decreased with immune week-age (P<0.05). Both FSHR and LHR mRNA expression levels were significantly higher in the treated group than in controls in the first three samples (P<0.05). When GnRHR was blocked by an antagonist in thymocytes, all reproductive hormone receptor gene expressions were significantly increased (P<0.001). In summary, these findings suggest that active immunization against GnRH can up-regulate GnRH receptor and gonadotropin receptor signaling, by stimulating thymic autocrine and paracrine function, whereas the androgen receptor is down-regulated due to a lack of testosterone secretion in the thymus.
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Affiliation(s)
- Shiping Su
- College of Animal Science and Technology, Anhui Agricultural University, No. 130 of Changjiang West Road, Hefei, Anhui 230036, PR China
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Turkstra JA, van der Staay FJ, Stockhofe-Zurwieden N, Woelders H, Meloen RH, Schuurman T. Pharmacological and toxicological assessment of a potential GnRH vaccine in young-adult male pigs. Vaccine 2011; 29:3791-801. [PMID: 21439319 DOI: 10.1016/j.vaccine.2011.03.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 03/03/2011] [Accepted: 03/07/2011] [Indexed: 10/18/2022]
Abstract
Active immunization against gonadotrophin-releasing hormone (GnRH) is successfully applied to prevent boar taint in pork. In men, GnRH immunization could be an alternative to hormone therapy in patients with prostate cancer. In this study, a new GnRH vaccine formulation (a modified GnRH peptide conjugate formulated with CoVaccine adjuvant) was investigated for its pharmacological efficacy and safety in young-adult male pigs. Immunization resulted in castrate-like plasma testosterone levels in all treated pigs from week 8 until the end of the study, 30 weeks after the first immunization. Testosterone depletion retarded testes growth, reduced the relative weight of the testes and accessory sex organs, and reduced sperm counts and motility. There was no clinically relevant toxicity. Typical vaccination-related adverse reactions, such as swelling at the injection site and fever, were considered acceptable. We conclude that this GnRH vaccine efficiently and rapidly reduced serum testosterone levels, without inducing chronic toxic effects, and therefore could be applicable in both veterinary and human medicine.
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Affiliation(s)
- J A Turkstra
- Pepscan Therapeutics, Zuidersluisweg 2, 8243 RC Lelystad, The Netherlands
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Lapidge SJ, Eason CT, Humphrys ST. A review of chemical, biological and fertility control options for the camel in Australia. Rangel J 2010. [DOI: 10.1071/rj09033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Since their introduction to Australia in 1840 the one-humped camel, Camelus dromedarius, has gone from the colonist’s companion to a conservationist’s conundrum in the fragile arid ecosystems of Australia. Current management techniques are failing to curb present population growth and alternatives must be sought. This review assess the applicability of currently registered and developmental vertebrate pesticides and fertility control agents for camel control, as well as examining the potential usefulness of known C. dromedarius diseases for biological control. Not surprisingly, little is known about the lethality of most vertebrate pesticides used in Australia to camels. More has been published on adverse reactions to pharmaceuticals used in agriculture and the racing industry. An examination of the literature on C. dromedarius diseases, such as camel pox virus, contagious ecthyma and papillomatosis, indicates that the infections generally result in high morbidity but not necessarily mortality and this alone may not justify their consideration for use in Australia. The possibility exists that other undiscovered or unstudied biological control agents from other camilid species may offer greater potential for population control. As a long-lived species the camel is also not ideally suited to fertility control. Notwithstanding, anti-fertility agents may have their place in preventing the re-establishment of camel populations once they have been reduced through mechanical, biological or chemical means. Delivery of any generic chemical or fertility control agent will, however, require a species-tailored pathway and an appropriate large-scale deployment method. Accordingly, we put forward avenues of investigation to yield improved tools for camel control.
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Janett F, Stump R, Burger D, Thun R. Suppression of testicular function and sexual behavior by vaccination against GnRH (Equity™) in the adult stallion. Anim Reprod Sci 2009; 115:88-102. [DOI: 10.1016/j.anireprosci.2008.11.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 10/24/2008] [Accepted: 11/13/2008] [Indexed: 10/21/2022]
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Fuchs T, Thun R, Parvizi N, Nathues H, Koehrmann A, Andrews S, Brock F, Klein G, Sudhaus N, Beilage EG. Effect of a gonadotropin-releasing factor vaccine on follicle-stimulating hormone and luteinizing hormone concentrations and on the development of testicles and the expression of boar taint in male pigs. Theriogenology 2009; 72:672-80. [DOI: 10.1016/j.theriogenology.2009.04.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 04/16/2009] [Accepted: 04/24/2009] [Indexed: 10/20/2022]
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Miller LA, Gionfriddo JP, Fagerstone KA, Rhyan JC, Killian GJ. The single-shot GnRH immunocontraceptive vaccine (GonaCon) in white-tailed deer: comparison of several GnRH preparations. Am J Reprod Immunol 2008; 60:214-23. [PMID: 18782282 DOI: 10.1111/j.1600-0897.2008.00616.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PROBLEM An effective, single-injection, multi-year, GnRH contraceptive agent is needed to control reproduction in overabundant white-tailed deer populations. METHOD OF STUDY Two GnRH conjugates, GonaCon (GnRH-KLH) and GonaCon-B (GnRH-blue protein), were prepared in emulsion form as one-injection and two-injection immunocontraceptive vaccine formulations. In addition, the GnRH-KLH protein conjugate was lyophilized and suspended in AdjuVac adjuvant to produce a fifth vaccine formulation. Each formulation was administered to a group of five captive adult female white-tailed deer. Reproductive performance of treated female deer was monitored for 5 years to determine the comparative efficacy of the various treatments. RESULTS The longevity of the contraceptive response (2-5 years) was strongly influenced by the design of the conjugate antigen, the adjuvant used, and the delivery form of the vaccine. CONCLUSION One-injection and two-injection formulations of GonaCon and GonaCon-B produced multi-year contraception in adult female white-tailed deer. GonaCon-B provided a longer lasting contraceptive effect.
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Affiliation(s)
- Lowell A Miller
- USDA/Wildlife Services, National Wildlife Research Center, CO 80521, USA.
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Abstract
Gonadotropin releasing hormone (GnRH) controls the activity of the gonadotrope cells of the pituitary gland and, as a consequence, is a critical component of the endocrine cascade that determines the growth, development, and functional activity of testicular tissue. The use of GnRH and GnRH analogs is common in domestic animal production systems. Although GnRH and GnRH analogs are most commonly used to control the fertility and reproductive events in female animals, GnRH agonists and antagonists are increasingly used to modulate the fertility, behavior, and productivity of male animals as well. This review will focus on recent advances in this use of GnRH agonists and antagonists.
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Affiliation(s)
- Thomas E Adams
- Department of Animal Science, University of California, Davis, CA 95616, USA.
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Abstract
Active GnRH immunization of boars inhibits LH and testicular steroids but the consequences for spermatogenesis are unknown. Six boars were immunized three times against GnRH at 20, 24 and 28 weeks. Another six boars served as controls. Plasma LH and FSH were determined at 28 and 31 weeks. Testosterone and cortisol were determined before killing the pigs at 32 weeks. Tissue samples were taken for histology and fluid from the seminiferous tubuli for steroid determination. Individual germ cells were counted in histological sections. The glucocorticoid receptor (GCR), mitosis of spermatogonia and apoptosis were characterized by immunocytochemistry. Immunization reduced LH and testosterone to base levels whereas FSH was not changed. Testis weight was reduced by 64% due to a loss of Leydig cell cytoplasm (90.3%) and a decrease of tubule diameters (60.6%). Except for A-spermatogonia, all other spermatogenic cells were reduced by about 60%. Mitosis was reduced in immunized boars. Expression of GCRs was limited to spermatogonia and differed between immunized boars (8% of spermatogonia) and controls (2%). In the controls, androgen concentrations in tubular fluid were tenfold higher compared with immunized boars. Cortisol concentrations were of the order of 40 nmol/l both in the tubular fluid and blood plasma. These concentrations did not differ between groups. Apoptosis occurred only in spermatogonia and pachytene spermatocytes and was twofold higher in immunized boars compared with controls. Thus the availability of glucocorticoids in the tubuli and the expression of GCRs initiate apoptosis, which in turn reduces sperm yield. Testosterone is known to be an inhibitor of GCR expression, thus increasing the efficiency of spermatogenesis.
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Affiliation(s)
- A Wagner
- Universität Hohenheim, Institut für Tierhaltung und Tierzüchtung, Fachgebiet Tierhaltung und Leistungsphysiologie (470A), Garbenstr. 17, 70599 Stuttgart, Germany
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Abstract
Tanyang is one of the most important sheep breeds in the northwest of China. However, there is no detailed data on sexual development and timing of puberty/sexual maturity of this breed. This experiment was designed to study the relationships between growth rate and sexual development by measuring body weight, testis diameter, and plasma testosterone concentrations, and observing sexual behavior through puberty from 3 to 8 months old of entire Tanyang ram lambs. At same time, to assess the potential efficacy and welfare benefits of non-surgical castration, the effect of active immunization against gonadotrophin-releasing hormone (GnRH) on sexual development and growth rate on ram lambs was evaluated, and compared with surgically castrated and entire lambs. The results showed that body weight increased at a constant rate from 3 to 8 months old of age. Testis diameter increased rapidly between 3 and 5 months, followed by a period of slow growth. Plasma testosterone concentrations increased sharply from 3 to 6 months of age (P<0.05), after which there were no significant changes from 6 to 8 months of age. Sexual behavior started from 5 months of age. After ram lambs were immunized against GnRH at 3 months of age, there was no increase in testis diameter in the first 4 months after immunization. Plasma testosterone concentrations remained at similar levels to surgically castrated lambs until 6 months of age, and the onset of sexual behavior was delayed, compared with entire ram lambs. GnRH immunization and surgical castration had no significant effect on the body weight by the end of this experiment. These results suggest that 4-5 months of age is a critical period for pubertal changes and testosterone plays an important role in the initiation of puberty and sexual maturity of Tanyang ram lambs in China. In addition, a single shot GnRH immunization at 3 months, acting as an alternative to surgical castration, is a practical method for Chinese Tanyang ram lambs, and provides animal welfare benefits.
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Affiliation(s)
- S Cui
- Department of Animal Physiology, College of Biological Sciences, China Agricultural University, Beijing 100094, China.
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Abstract
Active immunization against gonadotropin-releasing hormone (GnRH) was recognized in the 1970s as a potential means by which the reproductive system of mammals might be shut down for various practical and clinical reasons. Numerous studies in males have been performed since that time to determine the applicability of the technique as an alternative to surgical removal of the testes. Reasons for such immunocastration include improvement of meat and carcass characteristics for cattle, sheep, goats, and swine; improvement in feed efficiency relative to castrates in those same species; reduction in male aggressive behavior; reduction in male-associated odors in goats and swine; and fertility neutralization in pet species. Although application as a fertility control agent in men is unlikely, there is renewed interest in active immunization against GnRH as a means of treating prostate cancers and related steroid-dependent pathologies.
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Affiliation(s)
- D L Thompson
- Department of Animal Science, Louisiana Agricultural Experiment Station, LSU Agricultural Center, Baton Rouge, LA 70803, USA
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Kraeling RR, Barb CR, Rampacek GB, Thompson DL, Gibson JW, Sullivan SA, Simon B, Burns PJ. Luteinizing hormone response to controlled-release deslorelin in estradiol benzoate primed ovariectomized gilts. Theriogenology 2000; 53:1681-9. [PMID: 10968414 DOI: 10.1016/s0093-691x(00)00307-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Development of a controlled release formulation of gonadotropin releasing hormone that would stimulate a LH surge capable of reducing the time span of ovulations would greatly benefit reproductive management because a single timed insemination could be used. A dose-response study was conducted to determine if Deslorelin, a potent gonadotropin releasing hormone analogue, delivered via the SABER system, a biodegradable controlled release system, would stimulate an ovulatory-like LH surge in the pig. Twenty ovariectomized gilts, approximately 200 d old and 100 kg body weight (BW), received estradiol benzoate (15 microg/kg BW im) and 48 h later, the gilts were given deslorelin at 0, 12.5, 25.0, 50.0 or 100.0 microg im (n = 4 each treatment group). Compared to controls, mean blood deslorelin concentrations were still elevated at 30 h after deslorelin. Mean deslorelin magnitude, area under the curve and duration were sequentially greater (P<0.05) in a dose-dependent sequence. Compared to controls, serum LH concentrations were elevated (P<0.05) for 6 to 12 h after deslorelin. A dose-response relationship was absent for all parameters of LH secretion. Magnitude of the serum LH response was greatest (P<0.05) in the 12.5 microg and 50.0 microg groups, whereas area under the curve was lower (P<0.05) after 25.0 microg of deslorelin than after 12.5, 50.0 and 100.0 microg, which were not different from each other. Thus, no more than 12.5 microg of deslorelin is necessary to obtain maximum LH release in the model studied and doses less than 12.5 microg may also be effective.
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Affiliation(s)
- R R Kraeling
- Richard B. Russell Agricultural Research Center, ARS, USDA, Athens, GA 30604, USA.
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Abstract
OBJECTIVE To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old fillies. DESIGN A controlled vaccination dose rate experiment. ANIMALS Six 2-year-old Australian Stock Horse fillies were randomly allocated to three treatment groups; unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine. RESULTS Ovarian activity of the treated fillies was suppressed at the peak of breeding season while that of untreated controls continued normally. The control fillies displayed oestrous activity and behaviour. Suppression of ovarian activity occurred for 25 and 30 weeks in the 200 and 400 mg groups, respectively. These differences were not significant. Ovarian activity ceased 2 to 3 weeks after primary vaccination. Antibody titres were low (330) until after the booster immunisation when they rapidly peaked at 22,000 and 28,000 in the 200 mg and 400 mg groups, respectively. Plasma progesterone concentrations of the treated fillies remained below 3.18 nmol/L while GnRH was suppressed. The vaccine had no significant effect on plasma androstenedione concentrations. Recovery from the effect of the vaccine was associated with development of ovarian follicles, normal oestrous behaviour and ovulation. Three of the four treated fillies and one of the controls conceived during the next breeding season and foaled normally. All the treated fillies conceived and produced normal foals in the following two breeding seasons. CONCLUSION Both dose rates suppressed ovarian function and prevented oestrous behaviour. These effects were reversible and the subsequent fertility of the vaccinated fillies was normal.
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Affiliation(s)
- U Tshewang
- Veterinary Science Farm, University of Queensland
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Fitzgerald BP. Effects of administration of N-methyl-D,L-aspartate (NMA) on gonadotropin secretion in untreated and steroid-treated ovariectomized mares during the breeding season and in intact and ovariectomized mares during anestrus. Domest Anim Endocrinol 1996; 13:211-8. [PMID: 8738862 DOI: 10.1016/0739-7240(96)00016-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The purpose of this experiment was to investigate whether N-methyl-D,L-aspartate stimulated gonadotropin secretion in mares and to determine the response in two experimental paradigms where gonadotropin secretion is low or elevated. In Experiment 1, conducted during the breeding season (summer), eight long-term ovariectomized mares were treated daily for 21 d with progesterone plus estradiol (n = 4) or oil vehicle. Beginning on Day 14, each mare received, in a randomized design on alternate days, an intravenous injection of either 0, 0.5, 1.0, or 5.0 mg/kg NMA. Treatment with NMA was not accompanied by a change in gonadotropin release in vehicle-treated ovariectomized mares. In steroid-treated mares, gonadotropin values were suppressed compared with vehicle controls, but NMA only induced a significant increase in follicle-stimulating hormone (FSH) and only at the highest dose. In Experiment 2, the effect of the administration of NMA was compared in intact anestrous mares (n = 4) and long-term ovariectomized mares (n = 4) during the nonbreeding season. At the highest doses (1.0 and 5.0 mg/kg), NMA induced a significant increase in luteinizing hormone (LH) and FSH in intact mares. In contrast, pretreatment concentrations of LH and FSH were higher in long-term ovariectomized mares and NMA only increased LH, but not FSH, at the highest dose. The results demonstrate that the administration of NMA stimulates the release of LH and FSH in mares. During anestrus, ovarian intact mares appear more responsive than long-term ovariectomized mares. At high doses, NMA may induce differential release of the gonadotropins in long-term ovariectomized mares.
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Affiliation(s)
- B P Fitzgerald
- Department of Veterinary Science Maxwell Gluck Equine Research Center, University of Kentucky Lexington, 40546, USA
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Thompson DL, Garza F, St George RL, Rabb MH, Barry BE, French DD. Relationships among LH, FSH and prolactin secretion, storage and response to secretagogue and hypothalamic GnRH content in ovariectomized pony mares administered testosterone, dihydrotestosterone, estradiol, progesterone, dexamethasone or follicular fluid. Domest Anim Endocrinol 1991; 8:189-99. [PMID: 1906388 DOI: 10.1016/0739-7240(91)90055-o] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Thirty-five ovariectomized pony mares were used to study the relationships among luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) concentrations in blood (secretion), in pituitary (storage) and in blood after secretagogue administration, as well as the content of gonadotropin releasing hormone (GnRH) in hypothalamic areas, under various conditions of steroidal and nonsteroidal treatment. Five mares each were treated daily for 21 d with vegetable shortening (controls), testosterone (T; 150 micrograms/kg of body weight, BW), dihydrotestosterone (DHT; 150 micrograms/kg BW), estradiol (E2; 35 micrograms/kg BW), progesterone (P4; 500 micrograms/kg BW), dexamethasone (DEX; 125 micrograms/kg BW) or charcoal-stripped equine follicular fluid (FF; 10 ml). Secretagogue injections (GnRH and thyrotropin releasing hormone, TRH, at 1 and 4 micrograms/kg of BW, respectively) were given one d prior to treatment and again after 15 d of treatment. Relative to controls, treatment with T, DHT and DEX reduced (P less than .05) LH secretion, storage and response to exogenous GnRH, whereas treatment with E2 increased (P less than .05) these same characteristics. Treatment with P4 reduced (P less than .05) only LH secretion. Treatment with T, DHT, E2 and DEX reduced (P less than .05) FSH secretion, whereas treatment with P4 increased (P less than .05) it and FF had no effect (P greater than .1). All treatments increased (P less than .05) FSH storage, whereas only treatment with T and DHT increased (P less than .05) the FSH response to exogenous GnRH. Other than a brief increase (P less than .05) in PRL secretion in mares treated with E2, secretion of PRL did not differ (P greater than .1) among groups. Only treatment with E2 increased (P less than .01) PRL storage, yet treatment with T or DHT (but not E2) increased (P less than .05) the PRL response to exogenous TRH. Content of GnRH in the body and pre-optic area of the hypothalamus was not affected (P greater than .1) by treatment, whereas treatment with T, E2 and DEX increased (P less than .1) GnRH content in the median eminence. For LH, secretion, storage and response to exogenous GnRH were all highly correlated (r greater than or equal to .77; P less than .01). For FSH, only storage and response to exogenous GnRH were related (r = .62; P less than .01). PRL characteristics were not significantly related to one another. Moreover, the amount of GnRH in the median eminence was not related (P greater than .1) to any LH or FSH characteristic.
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Affiliation(s)
- D L Thompson
- Department of Animal Science, Louisiana State University Agricultural Center, Baton Rouge 70803
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