Effect of High Dose of Soybean Meal on the Histology and Function of the Thyroid Gland in Albino Rat at Pre- and Postpuberty

Abstract

The study aimed to determine the effect of soybean meal on the histological
structure and some functional parameters of the thyroid gland was investigated in
this study. For this purpose, 24 white male rats were divided into four groups each
of six rats, as following (G1): normal control rats, at the prepubertal life stage, were
dissected after 40 days from the weaning (i.e., from Postnatal Day "PND" 21),
(G2): prepubertal rats, were treated with high dose of soybean meal "40% of daily
diet" for 40 days after the weaning, (G3): normal control rats, at the postpubertal
stage, were dissected after 40 days from the puberty (i.e., from PND 60), (G4):
postpubertal rats, were treated with high dose of soybean meal (40%) for 40 days
after the puberty. Phenotypic, histological and physiological changes were
examined. The results reported that, consumption of soybean at prepuberty
decreased the thyroid activity by the increasing of the cold "inactive" follicles, while
at postpuberty, soybean caused hyperactivity of the thyroid which led to the
hyperplasia and hypertrophy, then to the goiter,significant increase in the ratio of
cold follicles in the (G2) and significant decrease in the (G4), significant decrease in
the height of follicular cell in the (G2) and significant increase in the (G4),
significant increase in the diameter of follicular lumen in the (G2) and significant
decrease in the (G4). Also, soybean meal caused significant increase in the body
weight and significant decline in (T3 and T4) hormones levels.From the results of
the present study, it is concluded that the high doses of the soybean affect adversely
the function and tissue of the thyroid at both life stages, pre and postpuberty.