WISHto analyse the effect of chronic β-casomorphin exposure on insulin domain of expression. (A) Insulin domain of exposure (black arrowheads) in WT zebrafish embryos exposed to 50 µg/ml of bBCM-5, bBCM-7, hBCM-5 and hBCM-7 from 3–6 dpf. (B) Statistical analysis of insulin domain of expression using Student's t-test. Fold change (compared to untreated control zebrafish embryos) shows insulin domain of expression significantly decreased following bBCM-5 or -7 exposure and significantly increased following hBCM-5 or -7 exposure. Data represent mean±s.e.m.; *P<0.05, **P<0.005; Student's t-test (n=20).