Acetylshikonin from Zicao exerts antifertility effects at high dose in rats by suppressing the secretion of GTH.

Zicao is being highlighted as a promising Chinese medicine due to all the beneficial effects that have been associated with its use. Unfortunately, studies on the toxicity of Zicao in different species are still missing and should be carried out. In this study, we investigated whether Acetylshikonin (AS) from Zicao has an anti-fertility effect through mating experiments and explored its underling mechanism. Sprague-Dawley rats received no treatment or were treated with 120, 360 or 1080 mg/kg AS extract by intragastric administration for 2 weeks. The rat pregnancy rate of the 1080 mg/kg dose group was significantly decreased relative to control group, while it recovered after a month of drug withdrawal, which indicated that the effect of antifertility is reversible. Serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels in rat were significantly decreased by AS. The secretion of FSH in rat anterior pituitary cells was decreased but the synthesis was not affected. AS reduced the number of developing follicle and mature follicle in rat ovarian cortical. Maybe all of these resulted from AS decreased the expression of synaptotagmin-1 and SNAP-25 which were the critical proteins of exocytosis. Our data suggested that AS at high dose can suppress the ability of pregnancy of the rats through decreasing serum FSH and LH levels by affecting exocytosis process of gonadotropic hormone (GTH).