A rapid and sensitive ELISA for rainbow trout maturational gonadotropin (tGtH II): validation on biological samples; in vivo and in vitro responses to GnRH.

A rapid and sensitive heterologous enzyme-linked immunosorbent assay (ELISA) was developed to measure rainbow trout maturational gonadotropin. Purified salmon maturational gonadotropin (sGtH II) was used as reference hormone. Optimization of the procedure was performed by using an anti-beta sGtH serum. Two procedures were developed: an equilibrium assay (which did not involve a preincubation step) which lasted for 8 hr and a nonequilibrium assay (which involved a preincubation step) which lasted for 26 hr. The nonequilibrium assay gave the best sensitivity (70 pg/ml sample). GtH II measurements on in vivo and in vitro samples from GnRH analogs or sGnRH experiments showed that the ELISA procedure could be used over a wide range of concentrations. The method was validated by comparing GtH II concentrations measured by both RIA and ELISA.