Effects of Spirometra erinacei plerocercoids on the growth of Snell dwarf mice.

Snell normal and dwarf mice were infected with Spirometra erinacei plerocercoids collected in Japan, to investigate the relationship between the growth-promoting effects of plerocercoids and the growth hormone releasing factor and the somatostatin--growth hormone--somatomedin axis in the host. Infection with plerocercoids caused increases in body weight and weights of muscle, liver, spleen and heart in the normal male mice, and increases in the head--body length, body weight and weights of muscle, liver, spleen, kidney and heart in the normal female mice, but did not increase the weight of the fat pad. Infection with plerocercoids caused increases in body weights and weights of muscle, liver and spleen in the male dwarf mice, and increases in the head--body length, body weight and weights of muscle, liver, spleen and kidney in the female dwarf mice. These observations suggest that plerocercoids promote the growth of dwarf mice as well as normal mice. As the dwarfism of Snell mice is due to a defective anterior pituitary gland, it seems that plerocercoids do not stimulate secretion of growth hormone from the pituitary. Accordingly, it seems to be more probable that the larvae secrete a growth hormone-like substance.