Production, release and olfactory detection of sex steroids by the tench (Tinca tinca L.)

Pinillos, M. L.; Guijarro, A. I.; Delgado, M. J.; Hubbard, Peter; Canario, Adelino V. M.; Scott, A. P.

http://hdl.handle.net/10400.1/3979

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Authors

Canario, Adelino V. M.

Scott, A. P.

Abstract(s)

The present study is concerned with pheromone communication in tench (Tinca tinca L.), establishing firstly whethermales have a high olfactory sensitivity to some typical teleost sex steroids and prostaglandins; and secondly whether males and females might be able to synthesise and release some of these steroids into the water. The C21 steroid, 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P)was found to give large electro-olfactogram responses with an estimated threshold of detection of 10−12 M. The male tench were equally sensitive to glucuronidated 17,20β-P (10−11.6 M) but 100 times less sensitive to sulphated 17,20β-P (11−9.7 M). Preliminary data from cross-adaptation studies suggest that both the free and conjugated forms are detected by the same olfactory receptor(s). Male tench also had high olfactory sensitivity to prostaglandin F2α (PGF2α) and 15-keto PGF2α (11−11.5 and 10−11.4 M). They were relatively insensitive, however, to testosterone (T), androstenedione (AD), 11-ketotestosterone (11-KT), 17β-oestradiol (E2), 17,20β,21-trihydroxy-4-pregnen-3-one (17,20β,21-P) and 17,20α-dihydroxy-4-pregnen-3- one (17,20α-P). Radioimmunoassays were used to measure the steroids in plasma and water and all samples were processed for themeasurement of free, sulphated and glucuronidated fractions. In females, free 17,20β-P, 17,20α-P, free and glucuronidated T, and AD in plasma showed the largest increases in response to injection with mammalian gonadotropin-releasing hormone analogue (GnRHa) or Ovaprim (a mixture of GnRHa and a dopamine inhibitor). Free 17,20β-P was released into the water at the greatest rate. Plasma concentrations of the two conjugated forms of 17,20β-P were also elevated 18 h after the administration of GnRHa, but not by as much as the free steroid. In males, AD and 11-KT showed the greatest increase in response to GnRHa and were moreover released into the water at a higher rate in the treated group than in the control. The data support a possible pheromonal role for free and glucuronidated 17,20β-P.

Keywords

Electro-olfactogram PGF2α 17,20β-P 17,20β-P-Glucuronide 17,20β-P-sulphate Pheromone Reproduction Steroid Teleost Tench

URI

http://hdl.handle.net/10400.1/3979

Citation

Pinillos, M. L.; Guijarro, A. I.; Delgado, M. J.; Hubbard, P. C.; Canario, A. V. M.; Scott, A. P.Production, release and olfactory detection of sex steroids by the tench (Tinca tinca L.), Fish Physiology and Biochemistry, 26, 2, 197-210, 2002.