A radioimmunoassay for 17α20β-dihydroxy-4-pregnen-3-one: Its use in measuring changes in serum levels at ovulation in Atlantic salmon (Salmo salar), coho salmon (Oncorhynchus kisutch), and rainbow trout (Salmo gairdneri)

Effect of Oceanographic Environments on Sexual Maturation, Salinity Tolerance, and Vasotocin Gene Expression in Homing Chum Salmon

“…The magnitudes of elevations were markedly different between two sexes. The female-specific elevation in plasma DHP levels at the final stages of gonadal maturation in several salmonid species have been reported (Wright and Hunt, 1982;Ueda et al, 1984). In the present study, the elevation of plasma DHP was coincident with the decrease in the VT mRNA levels.…”

Lymphocytopenia and interrenal activity during sexual maturation in the brown trout, Salmo trutta L.

“…Plasma cortisol levels were determined by radioimmunoassay, using previously validated techniques (Pickering & Pottinger, 1983). Particular attention was given to the possibility that 17a 20P-dihydroxy-4-pregnen-3-one (1 7a 20PP), a maturational steroid the plasma levels of which increase during the spawning season in rainbow trout (Wright & Hunt, 1982), would interfere with the assay. Cross-reactivity of the cortisol antiserum with 17a 20pP at the 50% level was 0.2.…”

?Classical? and ?non-classical? reproductive steroids in fish

“…We might also ask whether other steroids, which were not tested, would be even more effective. The availability of antisera for 17,20/3P led to further studies demonstrafing that a sharp peak of 17,20tiP occurred coincident with GVBD in vivo prior to natural or induced ovulation (Wright and Hunt, 1982;Scott et al, 1983). The assumption has now often been made that 17,20tiP is the maturation-inducing steroid (MIS) in teleost fish, and this steroid has been measured in females of more than 35 species of teleost.…”