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GH and IGF-I induction by passive immunization of rainbow trout Oncorhynchus mykiss (Walbaum) using a somatostatin-14 antibody

Lakeh, Amir Abbas Bazyar, Farahmand, Hamid, Mirvaghefi, Alireza, Kloas, Werner, Peterson, Brian C., Wuertz, Sven
Aquaculture 2011 v.316 no.1-4 pp. 99
Oncorhynchus mykiss, antibodies, egg yolk, fish, growth promotion, immunization, immunoglobulin Y, insulin-like growth factor I, laying hens, somatostatin, somatotropin, subcutaneous injection
Inhibition of the growth axis by somatostatinwas studied in juvenile rainbow trout using passive immunisation with a previously isolated somatostatin antibody (antiSS-14).Upon subcutaneous injection of laying hens (Gallus domesticus) with conjugated somatostatin-14 (SS-14), the antiSS-14 was isolated from egg yolk. Isolation of immunoglobulin was carried out at 40 days, revealing maximum IgY titre (IgY) at 3.22±0.08 compared to control (0.1±0.04) and highest total protein of 183±2 mg ml−1 compared to the control (85±3 mgml−1). To test the effects of antiSS-14 on the somatotropin axis, rainbow trout were passively immunised. Passive immunisationwith extracted IgY at a dilution of 1:25 increased GH plasma concentrations after 30min, reaching amaximumat 35±7 ng ml−1 after 120 min.GHremained elevated for over a day, returning to baseline at 2 days. At 1:100, GH increased and returned to normal after 2 days. At 1:25, IGF-I plasma concentrationswere increased at 30 min (277±74 ng ml−1, pb0.05), 120 min (212±77 ngml−1,pN0.05), 240 min (359±172 ng ml−1, pb0.05) and 1 day (259±117 ng ml−1, pb0.05) compared to the control (n=7, Tukey test), returning to baseline levels after 2 days (145±45 ng ml−1). In the 1:100 treatment group, slightly elevatedGHdid not induce IGF-I, which fluctuated between 13 8±15 ng ml−1 and 167±35 ng ml−1 (n=7, pN0.05) compared to the control fish, ranging from 131±10 ng ml−1 to 148±6 ngml−1. Passive immunisation thus demonstrates up-regulation of plasma GH and IGF-I, suggesting the blockage of SS-14 mediated growth inhibition. The simplicity of antiSS-14 production in chicken eggs and the upregulation of GH and IGF-I suggests a potential use for growth promotion in aquaculture.