RETRACTED: Melatonin Attenuates Dysregulation of the Circadian Clock Pathway in Mice With CCl4-Induced Fibrosis and Human Hepatic Stellate Cells

Abstract

Dysregulation of the circadian clock machinery is a critical mechanism in the pathogenesis of fibrosis. This study aimed to investigate whether the antifibrotic effect of melatonin is associated with attenuation of circadian clock pathway disturbances in mice treated with carbon tetrachloride (CCl4) and in human hepatic stellate cells line LX2. Mice received CCl4 5 μL/g body weight i.p. twice a week for 4 or 6 weeks. Melatonin was given at 5 or 10 mg/kg/day i.p., beginning 2 weeks after the start of CCl4 administration. Treatment with CCl4 resulted in fibrosis evidenced by the staining of α-smooth muscle actin (α-SMA) positive cells and a significant decrease of peroxisome proliferator-activated receptor (PPARα) expression. CCl4 led to a lower expression of brain and muscle Arnt-like protein 1 (BMAL1), circadian locomotor output cycles kaput (CLOCK), period 1–3 (PER1, 2, and 3), cryptochrome 1 and 2 (CRY1 and 2) and the retinoic acid receptor-related orphan receptor (RORα). The expression of the nuclear receptor REV-ERBα showed a significant increase. Melatonin significantly prevented all these changes. We also found that melatonin (100 or 500 μM) potentiated the inhibitory effect of REV-ERB ligand SR9009 on α-SMA and collagen1 expression and increased the expression of PPARα in LX2 cells. Analysis of circadian clock machinery revealed that melatonin or SR9009 exposure upregulated BMAL1, CLOCK, PER2, CRY1, and RORα expression, with a higher effect of combined treatment. Findings from this study give new insight into molecular pathways accounting for the protective effect of melatonin in liver fibrosis.

Melatonin and circadian rhythms in liver diseases: Functional roles and potential therapies

“…Another study demonstrated therapeutic effects of melatonin administration (5 or 10 mg/kg per day, i.p. injection) against CCl 4 ‐induced liver injury in mice with decreased liver fibrosis levels . This study found that administration of CCl 4 decreased expression of clock genes, such as BMAL1, CLOCK, PER1/2, CRY1/2, and melatonin treatment restored expression levels of these genes in the liver .…”

“…injection) against CCl 4 ‐induced liver injury in mice with decreased liver fibrosis levels . This study found that administration of CCl 4 decreased expression of clock genes, such as BMAL1, CLOCK, PER1/2, CRY1/2, and melatonin treatment restored expression levels of these genes in the liver . Stem cell therapy performs transplantation of stem cells to facilitate liver regeneration and improve conditions in various liver diseases including cirrhosis .…”

Assessment of the protective and therapeutic effect of melatonin against thioacetamide‐induced acute liver damage

“…The rats were randomly assigned to five groups of seven rats per group. Group I: served as control; group II: Mel group (10 mg/kg) a single dose intraperitoneally (IP) on the first day [ 18,19 ] ; group III: TAA group (300 mg/kg) two times with 24 hour intervals [ 14 ] ; group IV: Mel (10 mg/kg) + TAA (300 mg/kg) group; Mel was administered at a dose of 10 mg/kg (IP) 24 hours before the administration of TAA. After the administration of Mel, TAA was administered, 300 mg/kg two doses were given at 24‐hour intervals.…”

“…[ 16 ] Mel is known to protect against oxidative stress and various agent‐induced damage to the liver. [ 17,18 ] Tissue damage and repair mechanisms are important for the preservation of homeostasis. Following increased damage, this balance is deteriorated and triggers various cell death mechanisms (apoptosis, necrosis, autophagy, etc), causing cell destruction.…”

Protective role of melatonin in early‐stage and end‐stage liver cirrhosis

“…Furthermore, Hong et al demonstrated that a high dose of MT significantly reduced the serum levels of laminin, hyaluronic acid and hydroxyproline, thus attenuating liver fibrogenesis in a dose‐dependent manner. In addition to down‐regulating α‐smooth muscle actin (α‐SMA) and up‐regulating peroxisome proliferator‐activated receptor alpha (PPARα), MT up‐regulated expression of brain and muscle Arnt‐like protein 1 (BMAL1), circadian locomotor output cycles kaput (CLOCK), period 2 (PER2), cryptochrome 1 (CRY1) and RAR‐related orphan receptor‐α (RORα) to maintain the circadian clock machinery in CCl 4 ‐treated mice . MT treatment significantly abolished the activation of HSCs and increased the expression of nuclear factor erythroid‐2‐related factor 2 (Nrf2) while inhibiting the expression of profibrogenic genes such as MMP‐9, collagens I and III, TGF‐β, PDGF, connective tissue growth factor, amphiregulin and phospho‐SMAD3 in mice with CCl 4 ‐induced liver fibrosis .…”