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Effects on Testosterone, LH and Cortisol Concentrations, and on Testicular Ultrasonographic Appearance of Induced Testicular Degeneration in Bulls

Påverkan på plasmakoncentrationerna av testosteron, LH och kortisol samt på testikelvävnadens ultraljudskarakteristika, efter inducerad testikeldegeneration hos tjur.

Abstract

It is well known that heat stress has a detrimental effect on testicular functions. In addition to the alteration of semen quality and testicular damage, reproductive hormone secretion can be altered. The objective of this study was to decribe changes in plasma concentrations of testosterone, LH and Cortisol, as well as in testicular ultrasonographic appearance after induced testicular degeneration. Four Swedish Red and White bulls, aged 3 years, were used. They were fed according to Swedish standards. The scrotum was covered with an insulation device during 96 h. Semen was collected weekly 3 times before and up to 4 months after insulation. Testicular ultrasonography and clinical genital examination were performed with the same intervals. Heparinized blood samples were taken from the jugular vein at 2 h interval during 24 h every 2 weeks during the study. Blood samples were tested for the content of testosterone, LH and Cortisol. Data were analysed, using oneway analysis of variance of seminal data, clinical examination data as well as 24 h hormonal output data as perentage of mean individual pretreatment values. The use of a 5 MHz B-mode ultrasound unit did not contribute with an objective estimation of the degree of testicular degeneration. In 3 of the bulls testosterone levels had a tendency to decrease and LH to increase during the time of severe degeneration, whereas an opposite trend was seen during the regenerative phase, changes becoming significant 15 weeks after scrotal insulation. Variation between animals was big. Cortisol levels had a decreasing trend, changes being significant only in individual bulls at 10 and 15 weeks after scrotal insulation. One bull had to be treated separately as testosterone and LH patterns were deviating. It was concluded that severe testicular degeneration induces related changes in the levels of testosterone and LH.

Sammanfattning

Det är välkänt att varmestress negativt påverkar testikelfunktionen. Förutom den direkta testikelskadan och påverkan på spermabilden kan vissa reproduktionshormoner påverkas. Avsikten med denna studie var att beskriva förändringen i plasmakoncentrationerna av testosteron, LH och kortisol liksom förändringar av testikelvävnadens utseende på ultraljud efter en inducerad testikeldegeneration.

Fyra treåriga svenska röda och vita tjurar användes. De uppstallades vid institutionen och utfodrades enligt svensk standard. Skrotum täcktes av en isoleringspåse under 96 h. Spermaprov togs varje vecka 3 gånger före och upp till 4 månader efter skrotumisoleringen. Ultraljuds- och klinisk andrologisk undersökning utfördes med samma Intervall. Hepariniserat blod togs från jugularvenen varannan timme under 24 timmer varannan vecka. Blodproven analyserades med avseende på testosteron, LH och kortisol. Data från spermaprover, kliniska undersökningar och hormonanalyser överfördes till procentuella förändringar i förhållande till medelutgångsvärdena och analyserades statistiskt med hjälp av variansanalys.

Ultraljud, i form av en 5 MHz B-mode-apparat, kunde inte användas som ett objektivt bedömningssätt av testikeldegeneration.

Hos 3 av tjurarna hade testosteronnivåerna en tendens att minska och LH-nivåerna att öka under den tid då testikeldegeneration var som mest uttalad. Under regenerationsfasen sägs en motsatt tendens, vilken blev signifikant 15 veckor efter skrotumisoleringen. Variationen mellan tjurarna var stor. Kortisol hade en nedåtgående trend och förändringarna blev signifikanta endast för de enskilda tjurarna vid 10 och 15 veckor. En tjur måste anlyseras separat pga awikande testosteron- och LH-mönster. Slutsatsen kunde dras att grav testikeldegeneration orsakar förändringar i testosteron- och LH-nivåerna.

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Correspondence to G. Fredriksson.

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Sidibé, M., Franco, L.A., Fredriksson, G. et al. Effects on Testosterone, LH and Cortisol Concentrations, and on Testicular Ultrasonographic Appearance of Induced Testicular Degeneration in Bulls. Acta Vet Scand 33, 191–196 (1992). https://doi.org/10.1186/BF03547308

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Keywords

  • heat stress
  • scrotal insulation