Effects of a Long-Term Administration of Aqueous Extract of Prunella vulgaris L. on Survival, Spontaneous Thyroid Carcinoma and Neoplastic C-cell Hyperplasia in Rats

Abstract

Background: The continued global rise in thyroid carcinoma calls for alternative prevention and treatment strategies. Prunella vulgaris L. (PV) is a herbaceous plant with a medicinal property in the treatment of thyroid gland dysfunction, but its influence on thyroid carcinoma is unclear so far. This study was designed to investigate the effects of aqueous extract of PV on survival, spontaneous thyroid carcinoma and its preneoplastic lesion in rats.Methods: A total of 552 Wistar rats (half female and half male) were randomly assigned into 4 groups and given one of the following diets for 24 months: chow diet (control), 2.5 (low), 8.25 (middle) and 25 (high) g/kg bw PV diets. After intervention, serum metabolic parameters including indicators of liver and renal function, glucose and lipid profiles were measured. Histological examination was conducted to confirm the types of thyroid carcinoma and its preneoplastic lesion. Results: After intervention, serum aspartate transaminase of male rats in high PV group decreased significantly. No statistical differences among groups in terms of survival, body weight and other metabolic parameters were detected. In the control, low, middle and high PV groups, 14, 14, 15 and 8 rats developed thyroid carcinoma, respectively. Medullary thyroid carcinoma (MTC) emerged as the most common histological type in both sexes. Although PV failed to decrease risk of total thyroid carcinoma or each histological type, the incidence rates of neoplastic C-cell hyperplasia (CCH, a preneoplastic lesion of hereditary MTC) in PV groups were lower than that of control, and the lowest was observed in high PV group, manifesting as 5.25-time decrease in female rats and 5.5-time decrease in male rats.Conclusion: Our results suggested for the first time that, a long-term administration of aqueous extract of PV decreased the incidence of neoplastic CCH without impairing survival and metabolic parameters.