In the present study our objectives were (1) to follow the temporal patterns of testicular LH and FSH receptor (LH-R and FSH-R) concentrations and affinity (Ka) during sexual maturation in bulls, to see if such patterns could explain the control of rapid testicular growth that occurs after 25 weeks of age, when serum gonadotropin concentrations are low; (2) to see if transformation growth factors (TGF- alpha and beta 1, 2 and 3) and interleukins (IL-1 and IL-6) are produced in the developing bovine testis and if their concentrations change during development; (3) to see if the onset of puberty could be hastened by treating bull calves subcutaneously (sc) with 3 mg of bLH (n=6) or 4 mg of bFSH (n=6) once every 2 days, from 4 to 8 weeks after birth.
Mean LH-R concentrations decreased from 13 to 25 weeks of age and increased to 56 weeks of age (P<0.05). LH-RKa decreased from 9 to 17 weeks of age, increased to 29 weeks and declined to 33 weeks of age (P<0.05). FSH-R concentrations declined from 17 to 25 weeks of age then increased to 56 weeks of age (P<0.05). FSH-RKa increased from 17 to 25 weeks of age (P<0.05). Testicular TGF-alpha concentrations increased from 13 to 17 weeks of age, decreased to 21 weeks and from 33 to 56 weeks of age (P<0.05). Testicular TGF-beta 1 concentrations decreased from 17 to 21 weeks of age, increased to 25 weeks and decreased from 25 to 29 weeks of age (P<0.05). Testicular TGF-beta 2 concentrations increased from 5 to 17 weeks of age, decreased to 21 weeks, increased to 25 weeks and decreased at 29 weeks of age (P<0.05). Testicular TGF-beta 3 concentrations increased from 13 to 17 weeks of age, decreased to 21 weeks of age and from 25 to 29 weeks of age (P<0.05). Mean testicular IL-1 alpha concentrations decreased from 5 to 9 weeks of age and 13 to 21 weeks of age (P<0.01) while mean testicular IL-1 beta concentrations decreased from 13 to 17 weeks and 29 to 33 weeks of age (P<0.01). Mean IL-1 bioactivity increased from 13 to 17 weeks of age, decreased to 21 weeks, increased to 25 weeks, decreased to 29 weeks and decreased from 33 to 56 weeks of age (P<0.05). Mean testicular IL-6 concentrations decreased (P<0.05) from 9 to 13 weeks of age, increased (P<0.05) to 21 weeks, decreased (P<0.05) to 25 weeks of age, increased (P<0.05) to 29 weeks and decreased (P<0.01) to 56 weeks of age. <p>We concluded that high concentrations of gonadotropin receptors might be critical to initiate postnatal testis growth and support it after 25 weeks of age in the face of low serum gonadotropin concentrations. Testicular TGF-alpha concentrations were higher in calves than adults while concentrations of TGF-beta and IL-1 were higher in the early postnatal period than the peripubertal period. The changes in testicular concentrations of TGFs and ILs led us to suggest a possible local regulatory role in development. Testicular IL-6 concentrations were higher in prepubertal calves than adults. Treatment of bull calves with bFSH from 4 to 8 weeks of age increased testicular growth (SC), hastened the onset of puberty (SC ≥ 28 cm), and enhanced spermatogenesis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-01012007-222031 |
| Date | 02 January 2007 |
| Creators | Bagu, Edward Tshima |
| Contributors | Singh, Baljit, Rawlings, Norman C., Janz, David M., Chedrese, P. Jorge, Barth, Albert D. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-01012007-222031/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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