Ethanamizuril is a novel triazine compound that exhibits remarkable anticoccidial activity. Owing to its pharmacological properties, this study was conducted to evaluate the acute and 30-day oral toxicity of ethanamizuril. In the acute study, ethanamizuril was administered once by oral gavage to mice and rats. The calculated LD50 values for mice and rats were 5776 and 4743 mg per kg b.w, respectively, but the LD50 value for male rats was higher than that of female rats. In the subchronic study, male and female rats were fed with diets supplemented with 0, 20, 60 or 120 mg kg−1 ethanamizuril for 30 days. Treatment related clinical signs of alopecia on the back and neck of the animals were observed in the 60 and 120 mg kg−1 dose groups from the third week of treatment. Significant differences in haematological and biochemical parameters as well as organ-to-body weight ratios were detected between the 60 and 120 mg kg−1 groups. Histopathological observations revealed that 60 and 120 mg kg−1 ethanamizuril could induce focal hepatocellular necrosis and split phase. Slight renal tubule protein casts in the kidneys and alveolar wall thickening in the lungs were also observed in the high dose groups of both genders. The dietary no-observed-adverse-effect level (NOAEL) of ethanamizuril for 30 days was 20 mg kg−1 feed.

Estradiol (E2) is a first-line drug for osteoporosis (OP) treatment via promotion of osteoblastic proliferation and differentiation. However, a long-term use of E2 would produce side effects thus, it is imperative to discover safer and more effective drugs. Pinoresinol (PINO) has a similar chemical structure to E2. The present study aimed to investigate whether PINO could promote osteoblastic proliferation and differentiation and the potential mechanisms. After treatment with 0.1 µg/l PINO for 2 days, MC3T3-E1 cell migration was assessed by wound healing assay. Estrogen (E2) treatment served as a positive control. RT-qPCR and western blotting were used for mRNA and protein expression analyses. Alkaline phosphatase (ALP) activity assay and Alizarin red staining were performed to investigate the calcification and mineralization, and the cyclic AMP (cAMP) level was detected by enzyme-linked immunosorbent assay (ELISA). H89, an inhibitor of protein kinase A (PKA), was introduced to verify the role of cAMP/PKA in the effect of PINO on MC3T3-E1 cells. Cell viability was the highest under 48 h of 0.1 µg/l PINO treatment. After treatment with PINO, a significant increase was observed in the migration rate and the expression of collagen type I (Col-I), ALP, osteopontin (OPN), runt-related transcription factor 2 (Runx2) and bone morphogenetic protein-2 (BMP-2) (P<0.01). The ALP activity and Alizarin red size in PINO and E2 groups were notably increased. The increased cAMP, PKA and phosphorylated cAMP response element-binding protein (CREB) levels were also observed in the PINO group. Furthermore, H89 co-treatment abolished the positive effects of PINO on cell viability and migration. PINO had similar effects to E2 on the osteoblastic proliferation and differentiation, and these positive effects may be attributed to the regulation of the cAMP/PKA signaling pathway.

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