Production of coronary arteriosclerosis with sex hormones and human chorionic gonadotropin (HCG) in juvenile steelhead and rainbow trout, Salmon gairdneri.

Coronary arteries were examined for significant changes in myointimal hyperplasia in one-year old juvenile steelhead or rainbow trout treated with estradiol, testosterone or human chorionic gonadotropin (HCG). In one experiment juvenile steelhead trout were injected weekly with 2 microgram/g HCG, 5 microgram/g estradiol cypionate or 5 microgram/g testosterone cypionate for 50 days. Control fish were those killed prior to treatment or injected with fish saline or cottonseed oil. In two experiments juvenile nonanadromous rainbow trout were treated with estrogen and testosterone with the same weekly doses as juvenile steelhead for 42 and 30 days, respectively. In the first experiment juvenile rainbow were injected weekly with 2 microgram/g HCG. Juvenile rainbow treated with estradiol, testosterone and HCG and juvenile steelhead treated with testosterone had larger coronary lesions than untreated or control fish. Coronary hyperplastic nodules resembled morphologically those observed previously in sexually mature steelhead and rainbow trout. These data support the hypothesis that reproductive hormones are causal factors in spontaneously occurring arteriosclerosis in spawning Salmo gairdneri.