Toxicological evaluation of morning glory seed: subchronic 90-day feeding study.

Diets containing 0.8, 2.53 and 8.0% field variety morning glory seed were fed to male and female rats (20 per group) in a 90-day subchronic feeding study. Gross clinical observations, body weight, and feed and water intake were recorded weekly. At 90 days, all surviving rats were autopsied, organs were weighed, and blood chemistry analyses, haematology, and bone-marrow evaluation for evidence of clastogenic effects were performed. Tissues from control (0% seed) and high-dose (8.0% seed) rats were examined histologically. Effects of morning glory seed were noted mainly in the high-dose group of both sexes. These included increases in mortality, feed consumption (on a body-weight basis), water consumption, serum alkaline phosphatase and potassium, white blood cell count, and brain and liver weights (as a percentage of body weight); body-weight gain and serum glucose were decreased. Significant changes seen in high-dose females alone were: increased haemoglobin, serum constituents (urea nitrogen, glutamic-pyruvic transaminase, glutamic-oxaloacetic transaminase, and ornithine carbamyl transferase), and organ weights (heart, kidney, spleen and pancreas as a percentage of body weight), and decreases in serum albumin, total protein, albumin:globulin ratio, and calcium. Significant changes occurring in high-dose males alone were: increased testicular weight (as a percentage of body weight), increased serum phosphorus, and decreased serum cholesterol. Liver degeneration in the high-dose females was greater than that in the controls. Mortality at 8.0% seed in the diet was 40% in males and 10% in females. At 0.8% seed, the only parameter that differed significantly from that of the controls was a final body-weight reduction in females without a corresponding reduction in feed consumption.