Protective effects of melatonin against carbon tetrachloride-induced hepatotoxicity in rats: a light microscopic and biochemical study

Therapeutic Effect of Melatonin on CCl4-Induced Fibrotic Liver Model by Modulating Oxidative Stress, Inflammation, and TGF-β1 Signaling Pathway in Pinealectomized Rats

The study aimed to determine the CCl4-induced liver fibrosis model in pinealectomized rats and biochemically, immunohistochemically, and histopathologically investigate the therapeutic effect of melatonin on liver fibrosis. The surgical procedure for pinealectomy was performed at the beginning of the study, and the sham and pinealectomized rats were administered CCl4 dissolved in corn oil (1:1) alone every other day to induce liver fibrosis or together with melatonin (10 mg/kg) therapy for 15 days. Melatonin is an essential therapeutic agent and offers an alternative therapeutic strategy in CCl4-induced liver fibrosis by suppressing inflammation, oxidative stress, and the TGF-β1 signaling pathway. Treatment with melatonin ameliorated CCl4-induced liver fibrosis by restoring hepatocellular damage and reducing plasma AST, ALT, and ALP values. Melatonin increases the activity of SOD and CAT, which are important enzymes for antioxidant defence, and raises GSH levels, which further enhances antioxidant function. Also, melatonin reduced hepatic inflammation (IL-6 and IL-1β) and oxidative stress indices. Moreover, histopathological changes and immunohistochemical expression of TGF-β1 were restored following melatonin supplementation in the CCl4-induced liver fibrosis model in pinealectomized rats. Our study shows that melatonin supplementation has a beneficial effect in protecting the liver fibrosis induced by CCl4 in pinealectomized rats.

Therapeutic potential of melatonin in targeting molecular pathways of organ fibrosis

Fibrosis, the excessive deposition of fibrous connective tissue in an organ in response to injury, is a pathological condition affecting many individuals worldwide. Fibrosis causes the failure of tissue function and is largely irreversible as the disease progresses. Pharmacologic treatment options for organ fibrosis are limited, but studies suggest that antioxidants, particularly melatonin, can aid in preventing and controlling fibrotic damage to the organs. Melatonin, an indole nocturnally released from the pineal gland, is commonly used to regulate circadian and seasonal biological rhythms and is indicated for treating sleep disorders. While it is often effective in treating sleep disorders, melatonin's anti-inflammatory and antioxidant properties also make it a promising molecule for treating other disorders such as organ fibrosis. Melatonin ameliorates the necrotic and apoptotic changes that lead to fibrosis in various organs including the heart, liver, lung, and kidney. Moreover, melatonin reduces the infiltration of inflammatory cells during fibrosis development. This article outlines the protective effects of melatonin against fibrosis, including its safety and potential therapeutic effects. The goal of this article is to provide a summary of data accumulated to date and to encourage further experimentation with melatonin and increase its use as an anti-fibrotic agent in clinical settings.

Melatonin loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles reduce inflammation, inhibit apoptosis and protect rat's liver from the hazardous effects of CCL4

Liver is an important organ that carries out major important functions including the detoxification of harmful chemicals. Numerous studies have lately focused on the impact of various substances, such as chemical pollutants and pharmaceutical drugs, on the liver. Melatonin (Mel) has been reported for the protection against liver injury. In order to enhance Mel therapeutic benefits and prevent any potential negative effects, Mel has to be delivered to the injured liver. Therefore, the goal of the current investigation was to create Mel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (Mel-PLGA NPs) to alleviate carbon tetrachloride (CCL4)-induced liver damage in male Sprague Dawley rats. The prepared Mel-PLGA NPs were physically characterized to determine its size and charge. Moreover, Mel-PLGA NPs were examined, in vitro, to determine its antioxidant, anticoagulant, anti-inflammatory and cytotoxicity effects before being used in vivo. The effect of NPs on liver injury was evaluated through biochemical, immunological, histopathological examination and flow cytometry technique. Mel-PLGA NPs were smooth and spherical with no signs of aggregation and have in vitro antioxidant, anti-inflammatory and anticoagulant effects. NPs varied in size from 87 to 96 nm in transmission electron microscope images, while their hydrodynamic diameter was 41 nm and their zeta potential was -6 mV. Mel-PLGA NPs had encapsulation efficiency (EE%) and drug loading (DL%) of 59.9 and 12.5%, respectively. Treatment with Mel-PLGA NPs ameliorated all histopathological changes, in liver sections, that resulted from CCL4 administration; where, liver sections of treated groups were similar to those of healthy control GI. NPs administration were superior to free Mel and reversed the elevated levels of liver function enzymes, inflammatory cytokines and matrix metalloproteinases to their normal levels. Moreover, liver sections of groups treated with NPs showed negative immunostaining for nuclear factor-κB (NF-κB) and C-reactive protein indicating their anti-inflammatory behavior. Mel-PLGA NPs significantly protected liver from the toxicity of CCL4. The effective dose of NPs was 5 mg/kg indicating a reduction in the required Mel dose and its associated adverse effects.

Ameliorative Effects of Propolis and Royal Jelly against CCl4 -Induced Hepatotoxicity and Nephrotoxicity in Wistar Rats

Carbon tetrachloride (CCl₄ ) is known to have hepatotoxic and nephrotoxic effects. During the two-month CCl₄ exposure of Wistar rats, propolis extract (PE) and royal jelly (RJ) were added in order to test the potential protective effect against hepato-renal injury. Ketonuria, proteinuria, high creatinine and urea levels are the result of CCl₄ -induced nephrotoxicity. Severe disorders of hematological indicators indicate anemia; high values of leukocytes indicate inflammatory condition. Cytogenetic impairments in hepatocytes, aggregation of platelets, and hypoproteinemia indicate severe liver impairment. Results suggest a more significant protective role of RJ compared to PE. Both extracts regulated proteinuria, ketonuria, hypoproteinemia and reduced platelet aggregation in the hepatic circulation. The increase in the number of erythrocytes (RBC) suggest protective effects against anemia; the decrease in the number of leukocytes can be linked to anti-inflammatory effects. PE and RJ have a beneficial effect against hepato-renal injury, anemia and anti-inflammatory conditions caused by CCl₄ .

Putative abrogation impacts of Ajwa seeds on oxidative damage, liver dysfunction and associated complications in rats exposed to carbon tetrachloride

BACKGROUND

Industrial toxicants such as Carbon tetrachloride (CCl₄) are known to disrupt the oxidative-antioxidative balance, which generates excessive amounts of free radicals leading to chronic or acute liver damage. Natural antioxidants, including Ajwa, play an important role in protecting against hepatotoxicity.

METHODS AND RESULTS

This study investigated the prophylactic impacts of ajwa seeds aqueous extract (ASE) against hepatic oxidative injury in rats induced by CCl₄. Eighty male Wistar albino rats were equally assigned to eight groups: one group receive no treatment, four groups were received CCl₄-olive oil mixture [1:1(v/v)] (0.2 ml/100 g body weight (bw), intraperitoneally) two times/week for 4 weeks/rat alone or with 200 mg Vit. C/kg bw or 5 ml ASE/rat or both, and three groups received olive oil, Vit. C, or ASE. Vitamin C and ASE were orally administrated two weeks before CCl₄ injection and 4 weeks concomitant with CCl₄. Lipid peroxidation, lipogenesis-related genes, hepatic histopathology, Bax immunostaining and DNA fragmentation were assessed. ASE protected hepatic damage by suppressing oxidative stress and elevating activities of antioxidant enzymes, including superoxide dismutase and catalase. ASE also regulated hepatic dyslipidemia, hepatic lipid accumulation and expression of SREBP-1 and FAS genes in CCl₄-treated rats. ASE decreased apoptosis through inhibition of CCl₄ induced Bax activation in hepatocytes.

CONCLUSION

These observations provide evidence for the hepatoprotective potential of ASE via inhibiting hepatic lipogenesis and oxidative stress, suggesting being used as a natural product in attenuating CCl₄ induced oxidative damage, hepatotoxicity and associated dysfunction.

Possible application of melatonin treatment in human diseases of the biliary tract

Melatonin was discovered in 1958 by Aaron Lerner. Its name comes from the ability of melatonin to change the shape of amphibian melanophores from stellate to roundish. Starting from the 1980s, the role of melatonin in the regulation of mammalian circadian and seasonal clocks has been elucidated. Presently, several other effects have been identified in different organs. For example, the beneficial effects of melatonin in models of liver damage have been described. This review gives first a general background on experimental and clinical data on the use of melatonin in liver damage. The second part of the review focuses on the findings related to the role of melatonin in biliary functions, suggesting a possible use of melatonin therapy in human diseases of the biliary tree.

Crocin (active constituent of saffron) improves CCl4-induced liver damage by modulating oxidative stress in rats

Background

CCl4 is a widely used xenobiotic for the purpose of causing liver damage in experimental studies. In this study, we aimed to reveal the effects of crocin on liver injury caused by CCl4 via free radical scavenging properties.

Materials and methods

Animals were divided into five groups of 10: control; corn oil; crocin; CCl4; CCl4 + crocin. Tissue samples were carefully removed and separated for biochemical and histological investigations.

Results

CCl4 administration led to significant increases in MDA, SOD, CAT and TOS in liver tissue, and AST, ALT and ALP levels in plasma (p < 0.05). In addition, CCl4 caused significant decreases in GSH and TAS (p < 0.05). When animals were treated with crocin, high MDA, SOD, CAT, TOS levels, and AST and ALP activities decreased and GSH and TAS levels increased. Control group exhibited normal histological appearance; however extensive necrosis areas were detected in the CCl4 group. In the CCl4 + crocin group, pathological changes were markedly decreased and the appearance of liver tissue was almost similar to the control groups.

Conclusion

Our results showed that crocin suppresses oxidative stress with antioxidant properties and has a protective effect on tissue damage caused by CCl4.

The multiple protective roles and molecular mechanisms of melatonin and its precursor N-acetylserotonin in targeting brain injury and liver damage and in maintaining bone health

Melatonin is a neurohormone associated with sleep and wakefulness and is mainly produced by the pineal gland. Numerous physiological functions of melatonin have been demonstrated including anti-inflammation, suppressing neoplastic growth, circadian and endocrine rhythm regulation, and its potent antioxidant activity as well as its role in regeneration of various tissues including the nervous system, liver, bone, kidney, bladder, skin, and muscle, among others. In this review, we summarize the recent advances related to the multiple protective roles of melatonin receptor agonists, melatonin and N-acetylserotonin (NAS), in brain injury, liver damage, and bone health. Brain injury, including traumatic brain injury, ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, and newborn perinatal hypoxia-ischemia encephalopathy, is a major cause of mortality and disability. Liver disease causes serious public health problems and various factors including alcohol, chemical pollutants, and drugs induce hepatic damage. Osteoporosis is the most common bone disease in humans. Due in part to an aging population, both the cost of care of fracture patients and the annual fracture rate have increased steadily. Despite the discrepancy in the pathophysiological processes of these disorders, time frames and severity, they may share several common molecular mechanisms. Oxidative stress is considered to be a critical factor in these pathogeneses. We update the current state of knowledge related to the molecular processes, mainly including anti-oxidative stress, anti-apoptosis, autophagy dysfunction, and anti-inflammation as well as other properties of melatonin and NAS. Particularly, the abilities of melatonin and NAS to directly scavenge oxygen-centered radicals and toxic reactive oxygen species, and indirectly act through antioxidant enzymes are disscussed. In this review, we summarize the similarities and differences in the protection provided by melatonin and/or NAS in brain, liver and bone damage. We analyze the involvement of melatonin receptor 1A (MT1), melatonin receptor 1B (MT2), and melatonin receptor 1C (MT3) in the protection of melatonin and/or NAS. Additionally, we evaluate their potential clinical applications. The multiple mechanisms of action and multiple organ-targeted properties of melatonin and NAS may contribute to development of promising therapies for clinical trials.

The multiple functions of melatonin in regenerative medicine

Melatonin research has been experiencing hyper growth in the last two decades; this relates to its numerous physiological functions including anti-inflammation, oncostasis, circadian and endocrine rhythm regulation, and its potent antioxidant activity. Recently, a large number of studies have focused on the role of melatonin in the regeneration of cells or tissues after their partial loss. In this review, we discuss the recent findings on the molecular involvement of melatonin in the regeneration of various tissues including the nervous system, liver, bone, kidney, bladder, skin, and muscle, among others.

Melatonin mitigates thioacetamide-induced hepatic fibrosis via antioxidant activity and modulation of proinflammatory cytokines and fibrogenic genes

AIMS

The potential antifibrotic effects of melatonin against induced hepatic fibrosis were explored.

MAIN METHODS

Rats were allocated into four groups: placebo; thioacetamide (TAA) (200mg/kg bwt, i.p twice weekly for two months); melatonin (5mg/kgbwt, i.p daily for a week before TAA and continued for an additional two months); and melatonin plus TAA. Hepatic fibrotic changes were evaluated biochemically and histopathologically. Hepatic oxidative/antioxidative indices were assessed. The expression of hepatic proinflammatory cytokines (tumor necrosis factor-α, and interleukin-1β), fibrogenic-related genes (transforming growth factor-1β, collagen I, collagen, III, laminin, and autotaxin) and an antioxidant-related gene (thioredoxin-1) were detected by qRT-PCR.

KEY FINDINGS

In fibrotic rats, melatonin lowered serum aspartate aminotransferase, alanine aminotransferase, and autotaxin activities, bilirubin, hepatic hydroxyproline and plasma ammonia levels. Melatonin displayed hepatoprotective and antifibrotic potential as indicated by mild hydropic degeneration of some hepatocytes and mild fibroplasia. In addition, TAA induced the depletion of glutathione, glutathione s-transferase, glutathione peroxidase, superoxide dismutase, catalase, and paraoxonase-1 (PON-1), while inducing the accumulation of malondialdehyde, protein carbonyl (C=O) and nitric oxide (NO), and DNA fragmentation. These effects were restored by melatonin pretreatment. Furthermore, melatonin markedly attenuated the expression of proinflammatory cytokines and fibrogenic genes via the upregulation of thioredoxin-1 mRNA transcripts.

SIGNIFICANCE

Melatonin exhibits potent anti-inflammatory, antioxidant and fibrosuppressive activities against TAA-induced hepatic fibrogenesis via the suppression of oxidative stress, DNA damage, proinflammatory cytokines and fibrogenic gene transcripts. In addition, we demonstrate that the antifibrotic activity of melatonin is mediated by the induction of thioredoxin-1 with attenuation of autotaxin expressions.

Effects of Melatonin on Liver Injuries and Diseases

Liver injuries and diseases are serious health problems worldwide. Various factors, such as chemical pollutants, drugs, and alcohol, could induce liver injuries. Liver diseases involve a wide range of liver pathologies, including hepatic steatosis, fatty liver, hepatitis, fibrosis, cirrhosis, and hepatocarcinoma. Despite all the studies performed up to now, therapy choices for liver injuries and diseases are very few. Therefore, the search for a new treatment that could safely and effectively block or reverse liver injuries and diseases remains a priority. Melatonin is a well-known natural antioxidant, and has many bioactivities. There are numerous studies investigating the effects of melatonin on liver injuries and diseases, and melatonin could regulate various molecular pathways, such as inflammation, proliferation, apoptosis, metastasis, and autophagy in different pathophysiological situations. Melatonin could be used for preventing and treating liver injuries and diseases. Herein, we conduct a review summarizing the potential roles of melatonin in liver injuries and diseases, paying special attention to the mechanisms of action.

The effects of melatonin on liver functions in arsenic-induced liver damage

OBJECTIVE

Arsenic exposure is increasing in communities due to environmental pollution and industrial development. Arsenic is toxic to organ systems because it causes oxidative stress, enzymatic inhibition, and damage to protein structures. The liver, for example, is an organ that may be damaged by arsenic, and this damage may cause various clinical conditions like hepatic failure or cancer. Melatonin is a hormone that acts like an antioxidant, an anti-inflammatory agent, and a cytoprotective agent. In this study, we aimed to evaluate melatonin's protective effects on livers damaged by arsenic toxicity.

MATERIALS AND METHODS

Twenty-four Sprague-Dawley male rats were classified into three groups: a control group, an arsenic applied group, and an arsenic plus 10 mg/kg melatonin applied group. At the end of the fifteen-day experiment, the rats were sacrificed. Albumin, interleukin-6 (IL-6), total protein, alanine transaminase, aspartate transaminase, macrophage migration inhibitory factor, and monocyte chemotactic protein-1 measurements were obtained.

RESULTS

In rats with liver damage due to arsenic exposure, melatonin administration significantly decreased the levels of IL-6, macrophage migration inhibitory factor, and monocyte chemotactic protein-1 (p<0.001, p=0.02 and p=0.04, respectively).

CONCLUSION

After evaluating liver enzymes and inflammatory markers, this study determined that melatonin exposure improves liver tissue damage caused by arsenic exposure, with the degree of improvement varying based on the levels of arsenic exposure.

Therapeutic efficacy of ethanolic extract of Aerva javanica aerial parts in the amelioration of CCl4-induced hepatotoxicity and oxidative damage in rats

Background

Liver diseases, the fifth most common cause of global death, can be metabolic, toxin-induced, or infective. Though approximately 35 Saudi medicinal plants are traditionally used to treat liver disorders, the hepatoprotective potential of Aerva javanica has not been explored.

Objective

To investigate the antioxidative and hepatoprotective effect of Aerva javanica.

Design

Total ethanol extract of A. javanica aerial parts was prepared and tested on DCFH-toxicated HepG2 cells ex vivo, and in CCl₄-injured Wistar rats in vivo. MTT assay was used to determine cell viability and the serum biochemical markers of liver injury as well as histopathology was performed. In vitro 1,1-diphenyl-2-picrylhydrazyl and β-carotene free-radical scavenging assay and phytochemical screening of the extract were done. Furthermore, A. javanica total extract was standardized and validated by high-performance thin layer chromatographic method.

Results

MTT assay showed that, while DCFH-injured cells were recovered to ~56.7% by 100 µg/ml of the extract, a 200 µg/ml dose resulted in hepatocytes recovery by ~90.2%. Oral administration of the extract (100 and 200 mg/kg.bw/day) significantly normalized the serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, gamma-glutamyl transferase, alkaline phosphatase, bilirubin, cholesterol, high-density lipoprotein, low-density lipoprotein, very-low-density lipoprotein, triglyceride, and malondialdehyde levels, including tissue nonprotein sulfhydryl and total protein in CCl₄-injured rats. In addition, the histopathology of dissected liver also revealed that A. javanica cured the tissue lesion compared to silymarin treatment. In vitro assays revealed strong free-radical scavenging ability of the extract and presence of alkaloids, flavonoids, tannins, sterols, and saponins where rutin, a well-known antioxidant flavonoid, was identified.

Conclusions

Our findings demonstrate the potential of A. javanica in the attenuation of ex vivo and in vivo hepatotoxicity and oxidative damage. This further suggests its therapeutic value in various liver diseases. However, isolations of the active principles, their mechanisms of action, and other therapeutic contributions remain to be addressed.

Melatonin: the dawning of a treatment for fibrosis?

Fibrosis is a common occurrence following organ injury and failure. To date, there is no effective treatment for this condition. Melatonin targets numerous molecular pathways, a consequence of its antioxidant and anti-inflammatory actions that reduce excessive fibrosis. Herein, we review the multiple protective effects of melatonin against fibrosis. There exist four major phases of the fibrogenic response including primary injury to the organ, activation of effector cells, the elaboration of extracellular matrix (ECM) and dynamic deposition. Melatonin regulates each of these phases. Additionally, melatonin reduces fibrosis levels in numerous organs. Melatonin exhibits its anti-fibrosis effects in heart, liver, lung, kidney, and other organs. In addition, adhesions which occur following surgical procedures are also inhibited by melatonin. The information reviewed here should be significant to understanding the protective role of melatonin against fibrosis, contribute to the design of further experimental studies related to melatonin and the fibrotic response and shed light on a potential treatment for fibrosis.

Therapeutic value of melatonin post-treatment on CCl4-induced fibrotic rat liver

Melatonin is known for being beneficial in targeting liver diseases. This study aimed to investigate whether melatonin post-treatment is capable of rat carbon tetrachloride (CCl4)-induced liver fibrosis reduction. Thirty-two male Sprague-Dawley rats were divided into 4 groups: normal; fibrosis with CCl4 injection (1 mL/kg) twice weekly for 8 weeks; phosphate-buffered saline (PBS); and melatonin (20 mg/kg) for a further 4 weeks on cessation of CCl4. At the beginning of week 13, liver tissue samples were used for hematoxylin-eosin (H&E), periodic acid-Schiff (PAS), Masson’s trichrome (MT), and Oil Red O staining, quantitative real-time PCR (qRT-PCR) analysis of the matrix metalloproteinase-9 (MMP-9), MMP-13, transforming growth factor-β1 (TGF-β1), Bcl-2, and Bax genes as well as immunofluorescence (IF) of the first 3, and sera for measurement of aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin, and hydroxyproline. Chronic administration of CCl4 followed by considerable increase in tissue disruption, macro- and micro-vesicles, collagen, lipid droplets (LDs), AST, ALT, hydroxyproline, TGF-β1, and Bax, and decrease in glycogen depository, albumin, Bcl-2, MMP-9, and MMP-13; however, the pattern was reverse when it comes to melatonin treatment (for all p < 0.05). Our results reveal the beneficial aspects of melatonin in treatment of liver fibrosis probably via inhibition of TGF-β1expression.

Safe and symptomatic medicinal use of surface-functionalized Mn3O4 nanoparticles for hyperbilirubinemia treatment in mice

Aim: Testing the potential of citrate-capped Mn3O4 nanoparticles (NPs) as a therapeutic agent for alternative rapid treatment of hyperbilirubinemia through direct removal of bilirubin (BR) from blood in mice. Materials & methods: NPs were synthesized and the mechanism of BR degradation in presence and absence of biological macromolecules were characterized in vitro. To test the in vivo BR degradation ability of NPs, CCl4-intoxicated mice were intraperitoneally injected with NPs. Results: We demonstrated ultrahigh efficacy of the NPs in symptomatic treatment of hyperbilirubinemia for rapid reduction of BR in mice compared with conventional medicine silymarin without any toxicological implications. Conclusion: These findings may pave the way for practical clinical use of the NPs as safe medication of hyperbilirubinemia in human subjects.

Cranberry flavonoids prevent toxic rat liver mitochondrial damage in vivo and scavenge free radicals in vitro

The present study was undertaken for further elucidation of the mechanisms of flavonoid biological activity, focusing on the antioxidative and protective effects of cranberry flavonoids in free radical-generating systems and those on mitochondrial ultrastructure during carbon tetrachloride-induced rat intoxication. Treatment of rats with cranberry flavonoids (7 mg/kg) during chronic carbon tetrachloride-induced intoxication led to prevention of mitochondrial damage, including fragmentation, rupture and local loss of the outer mitochondrial membrane. In radical-generating systems, cranberry flavonoids effectively scavenged nitric oxide (IC50  = 4.4 ± 0.4 µg/ml), superoxide anion radicals (IC50  = 2.8 ± 0.3 µg/ml) and hydroxyl radicals (IC50  = 53 ± 4 µg/ml). The IC50 for reduction of 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) was 2.2 ± 0.3 µg/ml. Flavonoids prevented to some extent lipid peroxidation in liposomal membranes and glutathione oxidation in erythrocytes treated with UV irradiation or organic hydroperoxides as well as decreased the rigidity of the outer leaflet of the liposomal membranes. The hepatoprotective potential of cranberry flavonoids could be due to specific prevention of rat liver mitochondrial damage. The mitochondria-addressed effects of flavonoids might be related both to radical-scavenging properties and modulation of various mitochondrial events.

Hepatoprotective and antiviral efficacy of Acacia mellifera leaves fractions against hepatitis B virus

The present study investigated the hepatoprotective and anti-HBV efficacy of Acacia mellifera (AM) leaves extracts. The crude ethanolic-extract, including organic and aqueous fractions, were tested for cytotoxicity on HepG2 and HepG2.2.15 cells (IC₅₀ = 684 μg/mL). Of these, the ethyl acetate and aqueous fractions showed the most promising, dose-dependent hepatoprotection in DCFH-toxicated cells at 48 h. In CCl₄-injured rats, oral administration of AM ethanol extract (250 and 500 mg/kg·bw) for three weeks significantly normalized the sera aminotransferases, alkaline phosphatase, bilirubin, cholesterol, triglycerides, and lipoprotein levels and elevated tissue nonprotein sulphydryl and total protein. The histopathology of dissected livers also revealed that AM cured the tissue lesions. The phytochemical screening of the fractions showed presence of alkaloids, flavonoids, tannins, sterols, and saponins. Further, anti-HBV potential of the fractions was evaluated on HepG2.2.15 cells. Of these, the n-butanol and aqueous fractions exhibited the best inhibitory effects on HBsAg and HBeAg expressions in dose- and time-dependent manner. Taken together, while the ethyl acetate and aqueous fractions exhibited the most promising antioxidant/hepatoprotective and anti-HBV activity, respectively, the n-butanol partition showed both activities. Therefore, the therapeutic potential of AM extracts warrants further isolation of the active principle(s) and its phytochemical as well as biological studies.

Melatonin limits the expression of profibrogenic genes and ameliorates the progression of hepatic fibrosis in mice

We investigated whether melatonin ameliorates fibrosis and limits the expression of fibrogenic genes in mice treated with carbon tetrachloride (CCl4). Mice in treatment groups received CCl4 5 μL/g body weight intraperitoneally twice a week for 4 or 6 weeks. Melatonin was given at 5 or 10 mg/kg/d intraperitoneally, beginning 2 weeks after the start of CCl4 administration. Treatment with CCl4 resulted in fibrosis evidenced by the staining of Van Gieson and α-smooth muscle actin (α-SMA) positive cells in the liver. At both 4 and 6 weeks, CCl4 induced an increase in the messenger RNA levels of collagens I and III, transforming growth factor (TGF)-β, platelet-derived growth factor (PDGF), connective tissue growth factor (CTGF), amphiregulin, matrix metalloproteinase (MMP)-9, and tissue inhibitor of metalloproteinase (TIMP)-1. Protein concentrations of CTGF, amphiregulin, MMP-9, TIMP-1, and phospho-Smad3 were also significantly augmented in fibrotic mice. Melatonin successfully attenuated liver injury, as shown by histopathology and decreased levels of serum transaminases. Immunohistochemical staining of α-SMA indicated an abrogation of hepatic stellate cell activation by the indol. Furthermore, melatonin treatment resulted in significant inhibition of the expression of collagens I and III, TGF-β, PDGF, CTGF, amphiregulin, and phospho-Smad3. The MMP-9 activity decreased and the expression of nuclear factor erythroid-2-related factor 2 (Nrf2) increased in mice receiving melatonin. Data obtained suggest that attenuation of multiple profibrogenic gene pathways contributes to the beneficial effects of melatonin in mice with CCl4-induced liver fibrosis.

The effects of grape seed and colchicine on carbon tetrachloride induced hepatic damage in rats

This study aims to determine the effects of grape seed and colchicine on carbon tetrachloride (CCl4) induced hepatic damage and on some serum biochemical parameters. Sixty male Wistar albino rats (200-250 g) were randomly divided into six groups (ten rats/group) and included the control group the group were given isotonic sodium chloride (1 mL/kg b.w) intraperitonealy (i.p.), group 2 the group treated i.p. injection of CCl4 (1.0 mL/kg b.w) in corn oil twice in the first week, Groups 3 and 4 injected with CCl4 as described for group 2 and the rats were orally given (100 mg/kg b.w) GSE and i.p. injected (10 μg/rat) with colchicine for four weeks, respectively and groups 5 and 6 were the grape seed and colchicine control groups in which rats were orally given grape seed (100 mg/kg b.w) and i.p. injected with colchicine (10 μg/rat), respectively. Anorexia, weight loss, motionlessness and hepatic colour variation at necropsy were observed in groups 2, 3, and 4. Hyperemia, focal bleeding, fat degeneration, changes ranging from degenerative to necrotic, increase in connective tissue elements, pronounced in portal sites in particular, and infiltration of lymphoid series cell observed in the livers of the rats in group 2, treated with CCl4. Histological hepatic changes in the rats in group 3 and 4 were similar to those in group 2. The levels of serum total protein, albumin and globulin decreased in groups 2, 3, and 4, compared with groups 1, 5 and 6; aspartate transaminase (ALT) activities increased. The lowest alkaline phosphatase (ALP) activities were in groups 4 and 5. We concluded that GSE and colchicine have not sufficient ameliorative effects to CCl4 induced acute hepatic damage.

Melatonin regulation of biliary functions

The intrahepatic biliary epithelium is a three-dimensional tubular system lined by cholangiocytes, epithelial cells that in addition to modify ductal bile are also the targets of vanishing bile duct syndromes (i.e., cholangiopathies) such as primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) that are characterized by the damage/proliferation of cholangiocytes. Cholangiocyte proliferation is critical for the maintenance of the biliary mass and secretory function during the pathogenesis of cholangiopathies. Proliferating cholangiocytes serve as a neuroendocrine compartment during the progression of cholangiopathies, and as such secrete and respond to hormones, neurotransmitters and neuropeptides contributing to the autocrine and paracrine pathways that regulate biliary homeostasis. The focus of this review is to summarize the recent findings related to the role of melatonin in the modulation of biliary functions and liver damage in response to a number of insults. We first provide a general background on the general function of cholangiocytes including their anatomic characteristics, their innervation and vascularization as well the role of these cells on secretory and proliferation events. After a background on the synthesis and regulation of melatonin and its role on the maintenance of circadian rhythm, we will describe the specific effects of melatonin on biliary functions and liver damage. After a summary of the topics discussed, we provide a paragraph on the future perspectives related to melatonin and liver functions.

Rat liver mitochondrial damage under acute or chronic carbon tetrachloride-induced intoxication: protection by melatonin and cranberry flavonoids

In current societies, the risk of toxic liver damage has markedly increased. The aim of the present work was to carry out further research into the mechanism(s) of liver mitochondrial damage induced by acute (0.8 g/kg body weight, single injection) or chronic (1.6g/ kg body weight, 30 days, biweekly injections) carbon tetrachloride - induced intoxication and to evaluate the hepatoprotective potential of the antioxidant, melatonin, as well as succinate and cranberry flavonoids in rats. Acute intoxication resulted in considerable impairment of mitochondrial respiratory parameters in the liver. The activity of mitochondrial succinate dehydrogenase (complex II) decreased (by 25%, p<0.05). Short-term melatonin treatment (10 mg/kg, three times) of rats did not reduce the degree of toxic mitochondrial dysfunction but decreased the enhanced NO production. After 30-day chronic intoxication, no significant change in the respiratory activity of liver mitochondria was observed, despite marked changes in the redox-balance of mitochondria. The activities of the mitochondrial enzymes, succinate dehydrogenase and glutathione peroxidase, as well as that of cytoplasmic catalase in liver cells were inhibited significantly. Mitochondria isolated from the livers of the rats chronically treated with CCl₄ displayed obvious irreversible impairments. Long-term melatonin administration (10 mg/kg, 30 days, daily) to chronically intoxicated rats diminished the toxic effects of CCl₄, reducing elevated plasma activities of alanine aminotransferase and aspartate aminotransferase and bilirubin concentration, prevented accumulation of membrane lipid peroxidation products in rat liver and resulted in apparent preservation of the mitochondrial ultrastructure. The treatment of the animals by the complex of melatonin (10 mg/kg) plus succinate (50 mg/kg) plus cranberry flavonoids (7 mg/kg) was even more effective in prevention of toxic liver injury and liver mitochondria damage.

Hepatotoxic activity of toluene inhalation and protective role of melatonin

This study was designed to investigate the harmful effects of toluene inhalation in the liver of rats and possible protective effects of melatonin on these detrimental effects. For this purpose, 21 adult male Wistar-albino rats were randomly divided into three equal groups. Animals in group I were used as control. The rats in group II were exposed to toluene (3000 ppm/1 hour/day) for 4 weeks, while the rats in group III were treated with melatonin (10 mg/kg/day, intraperitoneally [ip]) plus toluene inhalation. At the end of the experimental period, liver and blood samples were taken from the decapitated animals. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin and albumin levels were determined. Liver tissue sections were stained with routine histological methods and examined under the light microscope. In addition, the sections were immunohistochemically stained using avidin-biotin-peroxidase method for determination of apoptosis. The liver tissue activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and malondialdehyde (MDA) levels were also measured. Toluene inhalation significantly increased serum ALT, AST and tissue MDA, and decreased serum albumin, but did not affect serum ALP, total bilirubin levels and tissue SOD, GSH-Px and CAT activity when compared with controls. The increases in tissue MDA and serum ALT and AST levels induced by toluene inhalation were significantly inhibited by melatonin treatment. In light microscopic observations of tissues from toluene-inhaled rats, massive hepatocyte degeneration, ballooning degeneration and mild pericentral fibrosis were observed. Bax immune reactivity was also increased significantly. Melatonin treatment decreased the balloon degeneration, fibrosis and Bax immune reactivity in the liver of toluene-inhaled rats. In view of the present findings, it is suggested that melatonin has hepatoprotective effects against toluene toxicity via primarily antioxidative properties.

Hepatoprotective actions of melatonin: Possible mediation by melatonin receptors

Melatonin, the hormone of darkness and messenger of the photoperiod, is also well known to exhibit strong direct and indirect antioxidant properties. Melatonin has previously been demonstrated to be a powerful organ protective substance in numerous models of injury; these beneficial effects have been attributed to the hormone’s intense radical scavenging capacity. The present report reviews the hepatoprotective potential of the pineal hormone in various models of oxidative stress in vivo, and summarizes the extensive literature showing that melatonin may be a suitable experimental substance to reduce liver damage after sepsis, hemorrhagic shock, ischemia/reperfusion, and in numerous models of toxic liver injury. Melatonin’s influence on hepatic antioxidant enzymes and other potentially relevant pathways, such as nitric oxide signaling, hepatic cytokine and heat shock protein expression, are evaluated. Based on recent literature demonstrating the functional relevance of melatonin receptor activation for hepatic organ protection, this article finally suggests that melatonin receptors could mediate the hepatoprotective actions of melatonin therapy.

In vivo hepatic oxidative stress because of carbon tetrachloride toxicity: protection by melatonin and pinoline

The protective in vivo effects of melatonin or pinoline on carbon tetrachloride (CCl(4))-induced oxidative damage were investigated in liver of rats and compared to rats injected only with CCl(4) (5 mL/kg body weight). Hepatic cell membrane fluidity, monitored using fluorescence spectroscopy, exhibited a significant decrease in animals exposed to CCl(4) compared to control rats. Increases in lipid and protein oxidation, as assessed by concentrations of malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA), and protein carbonylation, respectively, were also seen in hepatic homogenates of animals exposed to CCl(4). The administration of melatonin (10 mg/kg body weight) or pinoline injected 30 min before and 1 hr after CCl(4), fully prevented membrane rigidity and protein oxidation. However, treatment with melatonin was more effective in terms of reducing lipid peroxidation than pinoline, as the increases in MDA+4-HDA levels because of CCl(4) were reduced by 93.4% and 34.4% for melatonin or pinoline, respectively. Livers from CCl(4)-injected rats showed several histopathological alterations; above all, there were signs of necrosis and ballooning degeneration. The concurrent administration of melatonin or pinoline reduced the severity of these morphological changes. On the basis of the biochemical and histopathological findings, we conclude that both melatonin and pinoline were highly effective in protecting the liver against oxidative damage and membrane rigidity because of CCl(4). Therefore, these indoles may be useful as cotreatments for patients with hepatic intoxication induced by CCl(4).

Protective action of indole-3-acetic acid on induced hepatocarcinoma in mice

In this study, we report the protective effects of IAA on diethylnitrosamine (DEN)-induced hepatocarcinogenesis. BALB/c mice received daily IAA at 50 (T(50)), 250 (T(250)), and 500 (T(500)) mg Kg(-1) per body mass by gavage for 15 days. At day 15, animals were administered DEN and sacrificed 4 h later. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed in sera. In addition, hepatomorphologic alterations, activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), gene expression of antioxidant enzymes and DNA integrity were evaluated in the liver. IAA administration did not show any alterations in any of the parameters available, except for a reduction of the gene expression for antioxidant enzymes by 55, 56, 27, and 28% for SOD, CAT, GPx, and GR upon T(500), respectively compared with the control. Several hepatic alterations were observed by DEN exposure. Moreover, IAA administration at 3 doses was shown to provide a total prevention of the active reduction of CAT and GR induced by DEN exposure compared with the control. IAA at T(500) was shown to give partial protection (87, 71, 57, and 90% for respectively SOD, CAT, GPx, and GR) on the down-regulation of the enzymes induced by DEN and this auxin showed a partial protection (50%) on DEN-induced DNA fragmentation for both parameters when compared to DEN alone. This work showed IAA hepatocarcinogenesis protection for the first time by means of a DEN-protective effect on CAT and GR activity, and by affecting antioxidant gene expression and DNA fragmentation.

Protective effects of melatonin against formaldehyde-induced oxidative damage and apoptosis in rat testes: an immunohistochemical and biochemical study

This study investigated the protective effects of melatonin against formaldehyde-induced oxidative damage and apoptosis in rat testes. A total of 21 male Wistar rats were divided into three groups. Group I was used as a control, Group II was injected every other day with formaldehyde for 1 month, whereas Group III was injected every other day with formaldehyde and melatonin for 1 month. At the end of the experimental period animals were sacrificed and the testes removed and dissected from the surrounding tissues for immunohistochemical evaluation. In addition, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) were determined. The levels of SOD and GSH-Px decreased significantly, whereas the level of MDA significantly increased in animals treated with formaldehyde compared with the controls. Apoptosis of spermatogenetic and Leydig cells of testicular tissues was observed. In contrast, rats with melatonin SOD and GSH-Px enzyme activity increased whereas MDA levels decreased with formaldehyde exposure along with apoptosis. In view of the present findings, it is suggested that melatonin treatment may prevent formaldehyde-induced oxidative damage and apoptosis in rat testes.

Protective effect of melatonin against formaldehyde-induced kidney damage in rats

This study was undertaken to investigate the protective effects of melatonin against formaldehyde-induced renal damage in rats. For this purpose, 21 male Wistar rats were divided into three groups. The animals in Group I were used as a control, whereas the rats in group II were injected every other day with formaldehyde. The rats in group III received melatonin daily while exposed to formaldehyde. At the end of the 14-day experimental period, all rats were killed by decapitation, and the kidneys were removed. Some of the renal tissue specimens were used for determination of superoxide dismutase, glutatione peroxidase enzyme activities, and malondialdehyde levels. The remaining kidney tissue specimens were used for light microscopic evaluation. The renal tissue activities of superoxide dismutase and glutatione peroxidase were significantly decreased, and malondialdehyde levels were significantly increased in rats treated with formaldehyde compared with those of the control animals. In the light microscopic evaluation of this group, degenerative glomerules, vacuolization and dilatation of distal tubules, and vascular congestion were detected. However, an increase was observed in activities of superoxide dismutase and glutatione peroxidase enzymes, and a decrease of malondialdehyde levels in animals treated with formaldehyde plus melatonin was observed. Furthermore, the histopathological changes caused by formaldehyde were disappeared except for minimal tubular dilatation in this group. In conclusion, the biochemical and histological findings of our study suggest that melatonin administration prevents formaldehyde-induced oxidative renal damage in rats.

Inhibition of carbon tetrachloride–mediated apoptosis and oxidative stress by melatonin in experimental liver fibrosis

Melatonin, the principal secretory product of the pineal gland, functions as a potent antioxidant and free radical scavenger. Additionally, the antiapoptotic effect of melatonin has been observed both in vivo and in vitro. The aim of this experimental study was to investigate the protective effects of melatonin against carbon tetrachloride (CCl4)–induced apoptosis and oxidative stress in rat liver. Twenty-four male Wistar rats were divided in three equal groups. Group I was used as control. Rats in group II were injected every other day with CCl4 (0.5 mL/kg BW) for a month, whereas rats in group III were treated every other day with the same dose of CCl4 plus melatonin (25 mg/kg BW). At the end of the experiment, all animals were killed by decapitation and the livers were rapidly removed. Some of the liver tissue specimens were used for determination of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels. The remaining tissue specimens were processed for immunohistochemical assessment, and the percentage rates of apoptotic liver cells stained with immunoreactive Bax were determined. Chronic administration of CCl4 significantly increased liver MDA contents, as an end product of lipid peroxidation, and also significantly decreased SOD and GSH-Px activities, emphasizing the generation of increased oxidative stress. Moreover, it caused an evident increase in apoptotic cells. Melatonin treatment significantly reduced MDA levels and elevated SOD and GSH-Px activities in rats received CCl4 plus melatonin. Furthermore, apoptotic changes caused by CCl4 were considerably decreased in these animals. The results of the present study indicate that melatonin treatment substantially prevents CCl4-induced apoptosis and oxidative damage in the liver. Thus, melatonin may serve as a drug for treating many clinical conditions that arise from inappropriate apoptosis.

Pemoline (2-amino-5-phenyl-1,3-oxazol-4-one)-induced self-injurious behavior: a rodent model of pharmacotherapeutic efficacy

Self-injury is a devastating, maladaptive behavior disorder that is common in developmental disabilities and is comorbid with numerous psychiatric disorders. Examples of self-injurious behavior (SIB) include head-banging, self-biting, and self-punching. The neurochemical basis of SIB is unknown; however, many different classes of drugs are prescribed (e.g., neuroleptics, atypical neuroleptics, anti-epileptics, opioid antagonists) to reduce these behaviors. These drugs have all shown clinically significant but limited efficacy in patient populations, and no class of drug is effective for all patients. The development and characterization of a valid animal model could provide important information regarding the neurochemical basis of SIB and could be used to screen potential new pharmacotherapies. In one model of SIB, high doses of pemoline (2-amino-5-phenyl-1,3-oxazol-4-one) are administered to rats. Using this model, we evaluated the effectiveness of three drugs (risperidone, valproate, and topiramate) that reduce SIB in humans. We also screened the potential effectiveness of tramadol, a drug that decreases stereotyped and compulsive behaviors but has not been assessed in human self-injurers. We found that risperidone, valproate, and topiramate each significantly attenuate pemoline-induced SIB, whereas tramadol does not. These findings suggest that the pemoline model of SIB has predictive validity across a range of drug classes and implicate important potential neurochemical mechanisms that may contribute to the behavior disorder. The findings also indicate that tramadol may not be an effective pharmacotherapy for SIB.

Melatonin prevents formaldehyde-induced neurotoxicity in prefrontal cortex of rats: an immunohistochemical and biochemical study

This study was undertaken to investigate the protective effects of melatonin against formaldehyde-induced neurotoxicity in prefrontal cortex of rats. For this purpose, 21 male Wistar rats were divided into three groups. The rats in Group I were used as a control, while the rats in Group II were injected every other day with formaldehyde. The rats in Group III received melatonin daily while exposed to formaldehyde. At the end of 14-day experimental period, all rats were killed by decapitation. The brains of the rats were removed and the prefrontal cortex tissues were obtained from all brain specimens. Some of the prefrontal cortex tissue specimens were used for determination of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) levels. The remaining prefrontal cortex tissue specimens were used for immunohistochemical evaluation. The levels of SOD and GSH-Px were significantly decreased, and MDA levels, were significantly increased in rats treated with formaldehyde compared with those of the controls. In the immunohistochemical evaluation of this group, apoptotic cells were observed. However, increased SOD and GSH-Px enzyme activities, and decreased MDA levels, were detected in the rats administered melatonin while exposed to formaldehyde. Furthermore, apoptotic changes caused by formaldehyde were decreased in these rats. The results of our study suggest that melatonin treatment prevents formaldehyde-induced neuronal damage in prefrontal cortex.

Melatonin improves methanol intoxication-induced oxidative liver injury in rats

This study was performed to evaluate the effect of melatonin on methanol-induced liver injury. We evaluated the levels of malondialdehyde (MDA), protein carbonylation (PC), myeloperoxidase (MPO) activities and to assess lipid peroxidation, protein oxidation, neutrophil accumulation and nitrite which is a stable end product of nitric oxide respectively. We also studied superoxide dismutase, catalase, and glutathione peroxidase activities of liver tissue to evaluate the changes in the antioxidant status. Histopathological alterations were also determined. The experiment was performed on Wistar rats, which received intragastric 3 g/kg methanol as a 50% solution in isotonic saline once. After 6 and 24 hr all the drug received and intoxicated rats were killed under anesthesia. Pretreatment with melatonin (10 mg/kg) decreased the MDA levels significantly, restored the PC levels to the control, prevented the increase of nitrite level and MPO activity significantly and reversed to the control levels, prevented the reduction in all of the antioxidant enzyme activities. Additionally in melatonin treated group piecemeal necrosis, lobular lytic necrosis, and portal inflammation returned to normal histologic appearances when compared with methanol administration. In conclusion, melatonin has protective effects against methanol-induced hepatic injury.

Influence of indole acetic acid on antioxidant levels and enzyme activities of glucose metabolism in rat liver

Indole acetic acid (IAA) is an auxin and can be synthesized in animals. This compound is metabolized in vitro by peroxidase, producing reactive oxygen species. The toxic effect of indole acetic acid in leukocytes is associated with peroxidase activities and these processes have been implicated in activation of glucose and glutamine metabolism. However, studies in vitro have shown that IAA, in absence of peroxidase, is an antioxidant almost as high in potency as those of other indolic compounds. The purpose of this study was to investigate the possible involvement of a toxic effect of indole acetic acid in the liver, as evidenced by oxidative stress and enzyme activities of the glucose pathway. The animals received IAA by subcutaneous or gavage administration in a phosphate buffered saline (the control group received only the phosphate buffered saline). The other groups received IAA at concentrations of 1 mg, 18 mg and 40 mg per kg of body mass per day. Treatments with 18 mg and 40 mg IAA decreased the activity of catalase by both subcutaneous (30% and 26%) or gavage administration (19% and 28%), respectively. A similar effect was observed on the activity of glutathione peroxidase of animals exposed to 18 mg and 40 mg IAA: A decrease of 34% and 29%, respectively, for subcutaneous administration and a decrease of 29% and 25%, respectively, for gavage administration. However, in neither source of administration did the acid alter superoxide dismutase, glutathione reductase and myeloperoxidase activities. Another alteration was observed in respect of reduced glutathione content in this organ. The lipid peroxidation level showed a significant decrease with subcutaneous (30%, 29% and 24%) and gavage administration (25%, 26% and 24%) using 1 mg, 18 mg and 40 mg of IAA, respectively compared with the control. The reduced glutathione content and catalase activity in the plasma were not altered by either of the two methods of administration. In addition to these findings, after subcutaneous or gavage administration of IAA, the activities of hepatic enzymes of glucose metabolism were not affected (glucokinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and citrate synthase). Evidence is presented herein that IAA did not have a pro-oxidant effect in the liver as deduced from a reduction of catalase and glutathione peroxidase activities, a decrease of lipid peroxidation content and no alteration of the pool of reduced glutathione. The effects of IAA were independent of the way of administration.