Stimulatory and inhibitory effects of testosterone on testes in Atlantic salmon male parr

• Published in: Journal of Fish Biology
• Main Authors: Berglund, I., Antonopoulou, E., Mayer, I., Borg, B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1995
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1995.tb01925.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1995.tb01925.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1995.tb01925.x

Immature 1‐year‐old Atlantic salmon Salmo salar parr were implanted with Silastic capsules of different sizes filled with testosterone (T). Testosterone had both positive and negative effects on testicular weights, spermatogenesis and steroidogenesis. The positive effects: higher incidence of males with enlarged gonads, spermiation, and high plasma levels of 11‐ketotestosterone (11‐KT) and 17,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20β‐P), were most pronounced in males treated with small T capsules. The negative effects: suppression of gonadal development and depressed plasma levels of 11‐KT and 17,20β‐P compared with mature controls, were most evident in fish treated with large T capsules.