Sargassum species combined with Glycyrrhiza uralensis is a famous herbal pair in
traditional Chinese medicine, as one of the so-called "eighteen antagonistic medicaments." In the Chinese Pharmacopoeia, two different species of Sargassum, Sargassum pallidum and Sargassum fusiforme, are recorded but they are not clearly differentiated in clinical use. In this study, we aimed to determine whether the two species of Sargassum could result in different effects when combined with G. uralensis in
Haizao Yuhu Decoction (HYD), which is used for treating thyroid-related diseases, especially
goiter. HYD containing S. pallidum or S. fusiforme was administered to rats with
propylthiouracil-induced
goiter. After 4 weeks, pathological changes in the thyroid tissue and the relative thyroid weight indicated that HYD containing S. pallidum or S. fusiforme protected thyroid tissues from
propylthiouracil damage. Neither species increased the
propylthiouracil-induced decrease in serum levels of
thyroid hormones. However, there were some differences in their actions, and only HYD containing S. fusiforme abated the
propylthiouracil-induced elevation of serum
thyroid-stimulating hormone levels and activated
thyroglobulin mRNA expression.