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RESEARCH ARTICLE
Contents Vol 20(5)

Control of the koala (Phascolarctos cinereus) anterior pituitary-gonadal axis with analogues of GnRH

Camryn D. Allen A H , Michelle Burridge B , Mandy L. Chafer B , Vere N. Nicolson B , Sophia C. Jago B , Rosemary J. Booth C , Grant Fraser C , Traza-Jade Ensabella C , Yeng Peng Zee A , Geoff Lundie-Jenkins C , William V. Holt D , Allan T. Lisle E , Frank N. Carrick F , Jonathan D. Curlewis G , Michael J. D’ Occhio A and Stephen D. Johnston A
+ Author Affiliations
- Author Affiliations

A School of Animal Studies, The University of Queensland, Gatton, Queensland 4343, Australia.

B Dreamworld, Coomera, Queensland 4209, Australia.

C Environmental Protection Agency, Brisbane, Queensland 4000, Australia.

D Institute of Zoology, Regents Park, London NW1 4RY, England.

E School of Land, Crop and Food Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.

F Centre for Mined Land Rehabilitation, The University of Queensland, St Lucia, Queensland 4072, Australia.

G School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.

H Corresponding author. Email: callen@salk.edu

Reproduction, Fertility and Development 20(5) 598-605 https://doi.org/10.1071/RD07214
Submitted: 30 November 2007  Accepted: 7 April 2008   Published: 21 May 2008

Abstract

The aim of the present study was to determine whether analogues of gonadotrophin-releasing hormone (GnRH) could be used to both induce an acute testosterone response and suppress anterior pituitary function in male koalas, and induce a luteal phase in female koalas. Experiment 1 characterised the steroidogenic response of male koalas to administration of 30 μg (4.3 μg kg–1) natural-sequence GnRH. Intra-muscular injection of natural-sequence GnRH induced the release of LH and testosterone with peak concentrations at 30 min (3.7 ± 1.9 ng mL–1) and 2 h (5.4 ± 0.5 ng mL–1), respectively. In Experiment 2, a single injection of the GnRH antagonist acyline (100 μg (14.3 μg kg–1) or 500 μg (71.4 μg kg–1)) did not influence the testosterone response to subsequent injections of natural-sequence GnRH. In Experiment 3, 4 μg (~0.67 μg kg–1) of the GnRH agonist buserelin induced a luteal phase in five female koalas based on a LH surge, secretion of progestogen, and a normal-length oestrous cycle. The findings have shown that (1) natural-sequence GnRH can be used to test gonadotroph cell function and determine the testosterone-secreting capacity of male koalas, (2) the GnRH antagonist, acyline, at the dose rates used, does not suppress the pituitary-testis axis in male koalas, and (3) the GnRH agonist, buserelin, induces a normal luteal phase in female koalas.

Additional keywords: acyline, buserelin, GnRH agonist, GnRH antagonist, LH, natural-sequence GnRH, progestogen, Receptal, testosterone.


Acknowledgements

We are grateful to the zookeepers and volunteers at DFWP and DW for their help in blood sample collection, koala oestrus detection procedures and general animal husbandry. The authors thank Professor Jean Rivier of the Salk Institute (San Diego, CA, USA) for his generous supply of the antagonist and for his assistance with the experimental design and manuscript preparation. We also thank Dr Nancy Sherwood from the University of Victoria (Canada) for her expert advice with regard to data interpretation associated with the GnRH antagonist study. This project was funded by an Australian Research Council (ARC) Grant, the School of Animal Studies (SAS), The University of Queensland, and the Queensland Government Koala Enhanced Genetic Exchange Program (KEGEP).


References

Allen, C. D. , McKinnon, A. J. , Lisle, A. T. , D’Occhio, M. J. , and Johnston, S. D. (2006). Use of a GnRH agonist and hCG to obtain an index of testosterone secretory capacity in the koala (Phascolarctos cinereus). J. Androl. 27, 720–724.
| Crossref | GoogleScholarGoogle Scholar | PubMed | Asa C. S., and Porton I. J. (2005). ‘Wildlife Contraception: Issues, Methods, and Applications.’ (Johns Hopkins University Press: Baltimore.)

Blanshard W. H. (1994). Medicine and husbandry of koalas. In ‘Wildlife’. (Ed. Anon.) pp. 547–623. (University of Sydney Post-Graduate Committee in Veterinary Science: Sydney.)

Bradley, A. J. , and Stoddart, D. M. (1997). Plasma androgen, social position, and response to GnRH in the marsupial sugar glider Petaurus breviceps (Marsupialia: Petauridae). J. Zool. 241, 579–587.
Herbert C. A., Webley L. S., Trigg T. E., Francis K., Lunney D. H., and Cooper D. W. (2001). Preliminary trials of the GnRH superagonist Deslorelin as a safe, long-acting and reversible contraceptive for koalas. In ‘Conference on the Status of the Koala in 2001, Canberra’. (Australian Koala Foundation: Brisbane.)

Herbert, C. A. , Trigg, T. E. , and Cooper, D. W. (2004a). Effect of deslorelin implants on follicular development, parturition and post-partum oestrus in the tammar wallaby (Macropus eugenii). Reproduction 127, 265–273.
| Crossref | GoogleScholarGoogle Scholar | PubMed | Jackson S. M., Reid K., Spittle D., and Romer L. (2003). Koalas. In ‘Australian Mammals: Biology and Captive Management’. (Ed. S. M. Jackson.) pp. 145–179. (CSIRO Publishing: Melbourne.)

Jimenez-Severiano, H. , D’Occhio, M. J. , Lunstra, D. D. , Mussard, M. L. , Davis, T. L. , Enright, W. J. , and Kinder, J. E. (2007). Comparative response of rams and bulls to long-term treatment with gonadotropin-releasing hormone analogs. Anim. Reprod. Sci. 98, 204–224.
| Crossref | GoogleScholarGoogle Scholar | PubMed | McFarlane J. R. (1990). Endocrine factors influencing reproduction in male non-eutherian mammals. Ph.D. thesis, The University of Queensland, Brisbane.

National Health and Medical Research Council of Australia (2004). ‘Australian Code of Practice for the Care and Use of Animals for Scientific Purposes.’ (Australian Government Publishing Service: Canberra.)

Panyaniti, W. , Carpenter, S. M. , and Tyndale-Biscoe, C. H. (1985). Effects of hypophysectomy on folliculogenesis in the tammar Macropus eugenii (Marsupialia: Macropodidae). Aust. J. Zool. 33, 303–311.
| Crossref | GoogleScholarGoogle Scholar | Shaw G. (2006). Reproduction. In ‘Marsupials’. (Eds P. J. Armati, C. R. Dickman and I. Hume.) pp. 83–107. (Cambridge University Press: Cambridge.)

Sutherland, R. L. , Evans, S. M. , and Tyndale-Biscoe, C. H. (1986). Macropodid marsupial luteinizing hormone: validation of assay procedures and changes in concentrations in plasma during the oestrous cycle in the female tammar wallaby (Macropus eugenii). J. Endocrinol. 86, 1–12.


Wang, Z. , and Goonewardene, L. A. (2004). The use of MIXED models in the analysis of animal experiments with repeated-measures data. Can. J. Anim. Sci. 84, 1–11.


Watson, E. D. , Pedersen, H. G. , Thomson, S. R. M. , and Fraser, H. M. (2000). Control of follicular development and luteal function in the mare: effects of a GnRH antagonist. Theriogenology 54, 599–609.
| Crossref | GoogleScholarGoogle Scholar | PubMed |