The development of a testosterone stimulation test in the virginia opossum (Dedelphis virginiana) and its use in evaluating deslorelin contraception

Johnston, S. D., Camacho, F. C., Carillo, L., Guy, N., Govea, J., Martinez, O., Paras, A., Lisle, A. T. and D'Occhio, M. (2008) The development of a testosterone stimulation test in the virginia opossum (Dedelphis virginiana) and its use in evaluating deslorelin contraception. Reproduction, Fertility and Development, 20 5: 563-569. doi:10.1071/RD07215


Author Johnston, S. D.
Camacho, F. C.
Carillo, L.
Guy, N.
Govea, J.
Martinez, O.
Paras, A.
Lisle, A. T.
D'Occhio, M.
Title The development of a testosterone stimulation test in the virginia opossum (Dedelphis virginiana) and its use in evaluating deslorelin contraception
Formatted title
The development of a testosterone stimulation test in the virginia opossum (Dedelphis virginiana) and its use in evaluating deslorelin contraception
Journal name Reproduction, Fertility and Development   Check publisher's open access policy
ISSN 1031-3613
1448-5990
Publication date 2008-04-01
Sub-type Article (original research)
DOI 10.1071/RD07215
Open Access Status DOI
Volume 20
Issue 5
Start page 563
End page 569
Total pages 7
Editor Sharon Mortimer
Place of publication Collingwood, Australia
Publisher CSIRO Publishing
Language eng
Subject C1
070206 Animal Reproduction
970106 Expanding Knowledge in the Biological Sciences
0608 Zoology
Abstract The aims of the present study were to examine the variability of testosterone secretion in the Virginia Opossum over a 24 h period and to develop a testosterone stimulation test that would provide an index of the prevailing testosterone biosynthetic capacity of the testes; the latter was used to clinically evaluate the efficacy of a gonadotrophin-releasing hormone agonist contraceptive. Sexually-mature captive opossums (n = 12) located in Africam Safari (Mexico) sampled every 12 h over 24 h consistently showed basal (<0.21 ng mL(-1)) blood testosterone concentrations. Intra-muscular injection of buserelin (2 microg mL(-1)) and human chorionic gonadotrophin (hCG; 1000 IU) resulted in an increase (P < 0.05) of plasma testosterone concentrations with maximal concentrations (3.9 ng mL(-1) and 5.8 ng mL(-1) respectively) occurring 120 min after injection. Plasma testosterone declined relatively rapidly to basal concentrations after 240 min with hCG but remained elevated after the same period of time with buserelin. Male opossums treated with (n = 6) and without (n = 6) a controlled-release deslorelin implant (Suprelorin; 4.7 mg deslorelin) were evaluated over a 10-week period for changes in testosterone secretion (hCG stimulation test) and sperm production (spermatorrhea). At the end of this period, the animals were hemi-castrated and their relative testicular quantitative histology compared. Testosterone concentration decreased over the course of the study in both treated and control animals (P < 0.0001) but there was no apparent effect of deslorelin on testosterone secretion, testicular histology (relative proportions of testicular cell types and seminiferous tubule diameter), or sperm production (presence of sperm in the cauda epididymis or urine).
Formatted abstract
The aims of the present study were to examine the variability of testosterone secretion in the Virginia Opossum over a 24 h period and to develop a testosterone stimulation test that would provide an index of the prevailing testosterone biosynthetic capacity of the testes; the latter was used to clinically evaluate the efficacy of a gonadotrophin-releasing hormone agonist contraceptive. Sexually-mature captive opossums (n = 12) located in Africam Safari (Mexico) sampled every 12 h over 24 h consistently showed basal (<0.21 ng mL–1) blood testosterone concentrations. Intra-muscular injection of buserelin (2 μg mL–1) and human chorionic gonadotrophin (hCG; 1000 IU) resulted in an increase (P < 0.05) of plasma testosterone concentrations with maximal concentrations (3.9 ng mL–1 and 5.8 ng mL–1 respectively) occurring 120 min after injection. Plasma testosterone declined relatively rapidly to basal concentrations after 240 min with hCG but remained elevated after the same period of time with buserelin. Male opossums treated with (n = 6) and without (n = 6) a controlled-release deslorelin implant (Suprelorin; 4.7 mg deslorelin) were evaluated over a 10-week period for changes in testosterone secretion (hCG stimulation test) and sperm production (spermatorrhea). At the end of this period, the animals were hemi-castrated and their relative testicular quantitative histology compared. Testosterone concentration decreased over the course of the study in both treated and control animals (P < 0.0001) but there was no apparent effect of deslorelin on testosterone secretion, testicular histology (relative proportions of testicular cell types and seminiferous tubule diameter), or sperm production (presence of sperm in the cauda epididymis or urine)
Keyword Buserelin
GnRH
hCG
Suprelorin
Testicular histology
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Fri, 27 Mar 2009, 21:37:06 EST by Mrs Kathy Bachmann on behalf of School of Animal Studies