Pathological Mechanism of HSOS in Rats Induced by Different Doses of Monocrotaline / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the pathological changes of hepatic sinusoidal obstruction syndrome （HSOS） induced by different doses of monocrotaline （MCT） in rats， investigate the dose and duration of modeling， and elucidate the mechanism. MethodA total of 72 male SD rats were randomized into normal group （n=12）， and low-， medium-， and high-dose MCT groups （n=20 per group， 80，120，160 mg·kg-1， respecctively）. In the model groups， different doses of MCT were intragastrically administered to induce the HSOS in rats. After 48 h and 120 h separately， rats in each group were sacrificed and sampling was performed. The survival rate of rats in each group was calculated， and the body weight， liver weight， and and serum liver function indexes of the rats were examined. The histopathological changes of the liver were observed based on scanning electron microscopy， hematoxylin and eosin （HE） staining， and Sirius red （SR） staining. Glutathione S-transferase （GST） activity， total superoxide dismutase （T-SOD） activity， and malondialdehyde （MDA） content of liver tissue homogenate were measured with microplate method. The expression of liver tissue-related indexes was detected by real-time polymerase chain reaction （PCR）， Western blot， and immunohistochemistry. ResultThe activity of serum alanine aminotransferase （ALT） and aspartate aminotransferase （AST） in MCT groups rose with the increase in MCT dose （P<0.05， P<0.01） compared with that in the normal group. With the extension of modeling time， the activity of serum ALT and AST in the low-dose group decreased （P<0.01）， while the activity of them in the medium-dose and high-dose groups increased （P<0.01）. HE staining showed that hepatocyte necrosis， inflammatory cell infiltration， and erythrocyte accumulation in MCT groups. Electron microscopy demonstrated that fenestrae of liver sinusoidal endothelial cells widened and the sieve plates disappeared. Morever， the injury was worsened with the increase in MCT dose. In addition， the expression of CD44 in MCT groups was significantly reduced compared with that in the normal group （P<0.05， P<0.01）. SR staining showed that no positive staining was found in model groups after 48 h， while collagen deposition in portal areas and liver sinusoids could be seen in model groups after 120 h. MCT groups showed increase in MDA content and GST activity and decrease in T-SOD activity compared with the normal group， particularly the medium-dose and high-dose groups （P<0.01）， and the changes were dose-dependent after 120 h （P<0.01）. The protein expression of CD68 （pro-inflammatory macrophage marker） was raised with the increase in dosage， which was consistent with the results of immunohistochemistry （P<0.01）， while CD163 （anti-inflammatory macrophage marker） protein and mRNA expression was significantly decreased with the increase in dosage （P<0.01）. Western blot results showed that the expression of phosphorylated nuclear factor-κB/nuclear factor-κB （p-NF-κB/NF-κB） and phosphorylated protein kinase B/protein kinase B （p-Akt/t-Akt） was significantly increased in medium-dose and high-dose MCT groups （P<0.05，P<0.01）. The protein expression of α-smooth muscle actin （α-SMA） in liver tissues in MCT groups was significantly increased over time and with the increase in dose， and the mRNA expression of α-SMA， collagen type I α1 （Col1a1）， and collagen type Ⅳ α1 （Col4a1） showed the same trend （P<0.05， P<0.01）. The results of TUNEL staining showed that apoptotic cells were increased with the rise of MCT dose， while B-cell lymphoma-2（Bcl-2） /Bcl-2 associated X protein （Bax） was remarkably decreased （P<0.01）. ConclusionHSOS in rats induced by intragastric administration of different doses of MCT was aggravated with the increase of dosage. In the low-dose （80 mg·kg-1） MCT group， the liver healed spontaneously over time. However， liver damage caused by MCT of 120 mg·kg-1 and 160 mg·kg-1 aggravated over time， and even fibrosis and death occurred. The pathological mechanism of MCT-induced HSOS in rats may be that MCT triggered intense oxidative stress in liver tissue， thus activated pro-inflammatory macrophages to secrete large amounts of inflammatory factors， and further activated the NF-κB/Akt signalling pathway， leading to severe cell damage and death.