Expressions of LC3B, P62 and Beclin1 in the liver of rats with chronic fluorosis and the role of autophagy in liver injury induced by fluorosis / 中华地方病学杂志

ABSTRACT

Objective:To observe the protein and mRNA expressions of microtubule-associated protein 1 light chain 3 (LC3)B, P62 and Beclin1 in the liver of rats with chronic fluorosis, and to explore the role of autophagy in pathogenesis of liver injury induced by fluorosis.Methods:Using a group design, 54 SD rats were divided into 9 groups according to their weight (100 - 120 g) using a random number table method, each group with 6 rats, half male and half female. They were control group (NC group), low fluoride group (LF group), high fluoride group (HF group), NC + rapamycin (RAP) group, LF + RAP group, HF + RAP group, NC + chloroquine (CQ) group, LF + CQ group, and HF + CQ group. The NC group drank tap water (fluoride concentration was 0.5 mg/L), LF group drank fluoride water (fluoride concentration was 5.0 mg/L), HF group drank fluoride water (fluoride concentration was 50.0 mg/L); NC + RAP group, LF + RAP group and HF + RAP group were fed with corresponding drinking water, respectively, for 3 months, and then RAP (1.5 mg/kg) was intraperitoneally administered for 10 d; NC + CQ group, LF + CQ group and HF + CQ group were fed with corresponding drinking water, respectively, for 3 months, and then CQ (60 mg/kg) was intraperitoneally administered for 10 d. Bone and 24-hour urine samples of rats in each group were collected to detect the contents of bone fluoride and urine fluoride; liver histomorphological changes were observed through hematoxylineosin staining; protein and mRNA expressions of LC3B, P62 and Beclin1 in liver were detected by immunohistochemistry and real-time fluorescence quantitative PCR, respectively.Results:Compared with the NC group [(0.03 ± 0.00) mg/kg, (0.34 ± 0.08) mg/L], the contents of bone fluoride [(3.86 ± 0.08) mg/kg] and urine fluoride [(1.11 ± 0.16) mg/L] in HF group were higher ( P < 0.05). In the NC group, the lobule structure of liver tissue was clear, the hepatic cords were arranged in order, and the cell structure was normal. There were different degrees of hepatocyte edema in LF and HF groups. After intraperitoneal injection of RAP, compared with the corresponding fluoride group, the morphology of hepatocytes did not change significantly. After intraperitoneal injection of CQ, compared with the corresponding fluoride group, the liver cells showed obvious edema, and the degree of edema aggravated with the increase of fluoride concentration. Compared with the NC group, the protein expressions of LC3B and Beclin1 in HF group were higher ( P < 0.05), and the protein expression of P62 was lower ( P < 0.05). After intraperitoneal injection of RAP, the protein expressions of LC3B and P62 in LF + RAP group was lower than that in LF group ( P < 0.05); Compared with HF group, the protein expressions of LC3B and Beclin1 in HF + RAP group were lower ( P < 0.05). After intraperitoneal injection of CQ, protein expression of P62 in LF + CQ group was higher than that in LF group ( P < 0.05); Compared with HF group, protein expression of P62 in HF + CQ group was higher ( P < 0.05). Conclusions:Early (3 month) fluoride intake could promote autophagy and induce edema of hepatocytes in rats, and RAP had similar effects. CQ may induce liver injury by inhibiting autophagy of hepatocytes.