ENDOCRINE STRESS-RESPONSE AND ABNORMAL-DEVELOPMENT IN CARP (CYPRINUS-CARPIO) LARVAE AFTER EXPOSURE OF THE EMBRYOS TO PCB-126

To investigate whether PCB 126 exposure during embryonic development i nduces an endocrine stress response in larval carp, eggs were exposed, immediately after fertilization, for 48 h to water containing 0.01% e thanol (vehicle-control), 10(-11), 10(-10) or 10(-9) mol l(-1) PCB in 0.01% ethanol. Eggs incubated in water served as controls. After trans fer to PCB-free water, mortality, the incidence of yolk-sac and perica rdial oedema, wet and dry weight, rate of skin pigmentation, and whole -body contents of the stress hormones ACTH, a-MSH and cortisol were de termined at 48, 96, 144, 168, 192 and 216 h postfertilization. Except for the dry weight, all parameters of animals exposed to 10(-10) and 1 0(-9) mol l(-1) PCB increased in a concentration-related manner. Howev er, these changes became evident only at 144 h postfertilization, i.e. after resorption of the yolk-sac. Swelling of the yolk sac and perica rdium occurred, and whole-body ACTH, alpha-MSH and cortisol levels inc reased. Although animals exposed to 10(-10) and 10(-9) mol l(-1) PCB d isplayed stable but elevated whole-body ACTH and alpha-MSH levels unti l 216 h, whole-body cortisol concentrations gradually decreased from 1 68 h post-fertilization, and were significantly below control values a t 216 h post-fertilization. Exposure of the carp embryos to 10(-11) mo l l(-1) PCB only increased whole-body alpha-MSH levels. Increased whol e-body ACTH and cortisol levels indicate that PCB induces a stress res ponse in carp larvae, possibly mediated by a disturbed hydromineral ba lance (oedema). We further suggest that the PCB-stimulated body pigmen tation is mediated by a stimulation of alpha-MSH secretion.