Bestimmung von Sexualsteroiden in abgestoßener Haut der Gila-Krustenechse (Heloderma suspectum)

Zusammenfassung

Gegenstand und Ziel Die Messung in Hautanhangsgebilden wie Haaren oder Klauen bei Säugern oder in Federn bei Vögeln wird zur nicht invasiven Bestimmung von Steroidhormonen angewendet. Ziel dieser Arbeit war, in einer Pilotstudie an der Gila-Krustenechse zu testen, ob die Messung von Sexualsteroiden in abgeschilferter Haut bei Reptilien zur Erfassung der endokrinen Gonadenfunktion bzw. zur Geschlechtsbestimmung eingesetzt werden kann.

Material und Methoden Für die Untersuchungen standen abgestoßene Häute von 11 weiblichen und 7 männlichen adulten, geschlechtsreifen Tieren zur Verfügung. Große Hautstücke wurden zunächst mit einer Schere zerkleinert, unter flüssigem Stickstoff fein zermörsert und die Proben schließlich mit organischen Lösungsmitteln extrahiert. Die folgenden Parameter wurden in den getrockneten und rückgelösten Extrakten radioimmunologisch bestimmt: Progesteron (P4), Estradiol-17β (E2), Testosteron (T), freie Gesamtöstrogene (fGÖ) sowie freie plus konjugierte Gesamtöstrogene (fkGÖ).

Ergebnisse Für P4 (p = 0,0052) und E2 (p = 0,0079) wurden signifikante Geschlechtsunterschiede mit höheren Konzentrationen bei weiblichen im Vergleich zu männlichen Tieren gefunden. Unerwarteterweise ergaben sich bei weiblichen Tieren auch signifikant (p = 0,0232) höhere T-Messwerte als bei männlichen, wobei die Konzentrationen insgesamt nur geringfügig über der Nachweisgrenze lagen. Im Vergleich zu fGÖ waren die Konzentrationen an fkGÖ nur geringgradig höher und zwischen den beiden Geschlechtern bestanden keine signifikanten Unterschiede.

Schlussfolgerung und klinische Relevanz Auch wenn die in dieser Pilotstudie angewendeten Methoden aufgrund von Überlappungen zwischen den Geschlechtern weder allein noch in Kombination eine zuverlässige Geschlechtsbestimmung bei einzelnen Tieren erlaubten, könnte die Messung von Sexualsteroiden in abgestoßenen Häuten grundsätzlich eine nützliche Methode für die nicht invasive Geschlechtsbestimmung oder die Erfassung der endokrinen Gonadenfunktion bei bestimmten Reptilienarten sein.

Abstract

Objective Measurement of steroid hormones in skin appendages such as mammalian hair or claws and in avian feathers represents a recognized non-invasive method for the determination of these parameters. The aim of this pilot study in the Gila Monster was to investigate whether the measurement of sex steroids in shed skin may be employed for the monitoring of endocrine gonadal function or sex determination in reptiles.

Material and methods Shed skins were available from 11 female and 7 male adult and sexually mature animals. Large pieces of skin were initially cut into smaller pieces with scissors. The resultant dermal fragments were finely ground under liquid nitrogen and finally extracted with organic solvents. The following parameters were determined radioimmunologically in the dried and re-dissolved extracts: progesterone (P4), estradiol-17β (E2), testosterone (T), free total estrogens (fGÖ) and free plus conjugated total estrogens (fkGÖ).

Results For P4 (p = 0.0052) and E2 (p = 0.0079) significant sex differences were found with higher concentrations in females compared to males. Unexpectedly, the measured values for T were also significantly higher in females (p = 0.0232) than in males, with the concentrations overall only slightly above the detection limit. Compared to fGÖ, the concentrations of fkGÖ were only slightly higher, with no significant differences between both sexes.

Conclusion and clinical relevance In this pilot study, the methods employed did not allow for reliable sex determination in individual animals, neither alone nor in combination, due to an overlap between the sexes. In principle, however, the measurement of sex steroids in shed skins could represent a useful method for non-invasive sex determination or endocrine gonadal function assessment in certain reptile species.

Schlüsselwörter

Haut - Progesteron - Testosteron - Östrogene - nicht invasive Geschlechtsbestimmung - Reptilien

Key words

Skin - progesterone - testosterone - estrogens - non-invasive sex determination - reptiles

Publication History

Received: 24 July 2020

Accepted: 23 September 2020

Article published online:
04 December 2020

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