To explore the regulatory effects of the new exotic herbal medicine Maca on thyroid function in normal rats and rats with thyroid enlargement and observe its safety.Methods:Female Wistar rats were used to investigate the regulatory effects and safety of Maca on thyroid function in rats with thyroid enlargement.They were randomly divided using a random number table into control group,model group,positive drug group,high-dose Maca group,and low-dose Maca group.A thyroid enlargement model was induced by orally administering propylthiouracil(PTU) for 4 weeks.The positive drug group,high-dose Maca group,and low-dose Maca group received corresponding drugs.Thyroid tissue morphology,thyroid coefficient,thyroid hormone synthesis,regulation,liver and kidney tissue morphology,and liver and kidney function-related indicators were observed.Additionally,female Wistar rats were used to investigate the regulatory effects of Maca on thyroid function in normal rats,and they were randomly divided into a control group and four Maca groups with different doses.Except for the control group,the other four groups received corresponding drugs.Thyroid coefficients were statistically calculated and related indicators of thyroid hormone synthesis and regulation were measured.Results:Compared with the model group,rats in the Maca groups showed increased body weight(P<0.05),increased levels of T3,T4,FT3,FT4,TRH,Tg,TPO,TSHR(P<0.05),decreased TSH levels(P<0.05),increased GLB levels(P<0.05),and decreased TP,ALB levels,and A/G ratio(P<0.05).Differences in GPT,GOT,Urea,and Cr were not statistically significant(P>0.05).There were no significant differences in thyroid coefficient or morphology of thyroid,liver,and kidney tissues.Maca had no significant effect on body weight,thyroid coefficient,T3,T4,FT3,FT4,TSH,TRH,Tg,TPO,and TSHR levels in normal rats(P>0.05).Conclusion:Maca has a certain therapeutic effect on thyroid hypofunction in rats with thyroid enlargement,without adverse effects on thyroid function in normal rats.The safety of Maca in rats with thyroid enlargement was also not observed.