The effect of the implantation of Spirometra mansonoides spargana in the growing rat.

Abstract

Mueller and Reed (1) have reported that the implantation of S. mansonoides spargana in normally growing rats did not enhance body weight gain. This was in contrast to their findings of marked weight gain in normal mice, hamsters, and hypothyroid and hypophysectomized rats implanted with spargana. Steelman et al. (2) have shown that the adult plateaued female rat responds to spargana implants with a body weight increase similar to that produced by growth hormone. Due to the close similarities of the biological profiles of growth hormone and sparganum growth factor (SGF), it was of interest to conduct a more detailed examination of the effects of spargana implants in intact growing male and female rats. Preliminary experiments suggested that endogenous growth hormone secretion may be modified in spargana-implanted animals. Methods. Groups of male and female rats (Carworth Farms), whose average body weights were from 100 to 160 g, were employed in the studies. In any one experiment, animals were allocated into groups on the basis of fasted body weight in such a manner that the average group body weights were the same and the standard errors of the mean body weights were comparable. All animals were fed standard laboratory chow pellets and tap water ad libitum, and were maintained in individual cages under constant temperature and lighting conditions. Clipped scolices (approx 1 cm in length) of spargana were used for implantation (2) and were suspended in physiological saline and injected subcutaneously into the dorsal side of the neck using a syringe with an 18 gauge needle. Ten scolices were implanted in each animal. The control animals received no implants. In the initial study, groups of 15 male and female rats were implanted with spargana and were maintained for 14 days.