Thymoquinone improves cognitive and hippocampal long-term potentiation deficits due to hepatic encephalopathy in rats

Document Type : Original Article


1 Persian Gulf Physiology Research Center. Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz- Iran

2 Department of Physiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

3 Department of Immunology, Cellular & Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

4 Department of Anatomical Sciences, Cellular & Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz. Iran

5 Medicinal Plant Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran


Objective(s): Hepatic encephalopathy (HE) is a neuropsychiatric syndrome that causes brain disturbances. Thymoquinone (TQ) has a wide spectrum of activities such as antioxidant, anti-inflammatory, and anticancer. This study aimed to evaluate the effects of TQ on spatial memory and hippocampal long-term potentiation (LTP) in rats with thioacetamide (TAA)-induced liver injury and hepatic encephalopathy.
Materials and Methods: Adult male Wistar rats were divided into six groups randomly: 1) Control; 2) HE, received TAA (200 mg/kg); 3-5) Treated groups (HE+TQ5, HE+TQ10, and HE+TQ20). TQ (5, 10, and 20 mg/kg) was injected intraperitoneally (IP) for 12 consecutive days from day 18 to 29. Subsequently, spatial memory performance was evaluated by the Morris water maze paradigm and hippocampal LTP was recorded from the dentate gyrus (DG) region. Activity levels of Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured in the hippocampal tissue.
Results: Data showed that the hippocampal content of MDA was increased while SOD activities were decreased in TAA-induced HE. TQ treatment significantly improved spatial memory and LTP. Moreover, TQ restored the levels of MDA and SOD activities in the hippocampal tissue in HE rats.
Conclusion: Our data confirm that TQ could attenuate cognitive impairment and improve LTP deficit by modulating the oxidative stress parameters in this model of HE, which leads to impairment of spatial cognition and LTP deficit. Thus, these results suggest that TQ may be a promising agent with positive therapeutic effects against liver failure and HE defects.


1. Erceg S, Monfort P, Cauli O, Montoliu C, Llansola M, Piedrafita B, et al. Role of extracellular cGMP and of hyperammonemia in the impairment of learning in rats with chronic hepatic failure: therapeutic implications. Neurochem Int 2006; 48:441-446.
2. Leise MD, Poterucha JJ, Kamath PS, Kim WR, editors. Management of hepatic encephalopathy in the hospital. Mayo Clin Proc 2014 ;89: 241-53.
3. Weissenborn K, Ennen JC, Schomerus H, Rückert N, Hecker H. Neuropsychological characterization of hepatic encephalopathy. J Hepatol 2001; 34:768-773.
4. Weissenborn K, Giewekemeyer K, Heidenreich S, Bokemeyer M, Berding G, Ahl B. Attention, memory, and cognitive function in hepatic encephalopathy. Metab Brain Dis 2005; 20:359-367.
5. Butterworth RF, editor The neurobiology of hepatic encephalopathy. Semin Liver Dis 1996; 16:235-244.
6. Erceg S, Monfort P, Hernández-Viadel M, Rodrigo R, Montoliu C, Felipo V. Oral administration of sildenafil restores learning ability in rats with hyperammonemia and with portacaval shunts. Hepatology 2005; 41:299-306.
7. Méndez M, Méndez-López M, López L, Aller MÁ, Árias J, Cimadevilla JM, et al. Spatial memory alterations in three models of hepatic encephalopathy. Behav Brain Res 2008; 188:32-40.
8. Huang L-T, Hsieh C-S, Chou M-H, Chuang J-H, Liou C-W, Tiao M-M, et al. Obstructive jaundice in rats: Cause of spatial memory deficits with recovery after biliary decompression. World J Surg 2004; 28:283-287.
9. Cauli O, Rodrigo R, Piedrafita B, Boix J, Felipo V. Inflammation and hepatic encephalopathy: Ibuprofen restores learning ability in rats with portacaval shunts. Hepatology 2007; 46:514-519.
10. Monfort P, Erceg S, Piedrafita B, Llansola M, Felipo V. Chronic liver failure in rats impairs glutamatergic synaptic transmission and long-term potentiation in hippocampus and learning ability. Eur J Neurosci 2007; 25: 2103-2111.
11. Monfort P, Cauli O, Montoliu C, Rodrigo R, Llansola M, Piedrafita B, et al. Mechanisms of cognitive alterations in hyperammonemia and hepatic encephalopathy: therapeutical implications. Neurochem Int 2009; 55:106-112.
12. Aguilar M, Miñarro J, Felipo V. Chronic moderate hyperammonemia impairs active and passive avoidance behavior and conditional discrimination learning in rats. Exp Neurol 2000; 161:704-713.
13. Monfort P, Corbalán R, Martinez L, López-Talavera J-C, Córdoba J, Felipo V. Altered content and modulation of soluble guanylate cyclase in the cerebellum of rats with portacaval anastomosis. Neuroscience 2001; 104:1119-1125.
14. Monfort P, Muñoz Ma-D, Felipo V. Hyperammonemia impairs long-term potentiation in hippocampus by altering the modulation of cGMP-degrading phosphodiesterase by protein kinase G. Neurobiol Dis 2004; 15:1-10.
15. Butterworth RF. Hepatic encephalopathy: A central neuroinflammatory disorder? Hepatology 2011; 53:1372-1376.
16. Avraham Y, Israeli E, Gabbay E, Okun A, Zolotarev O, Silberman I, et al. Endocannabinoids affect neurological and cognitive function in thioacetamide-induced hepatic encephalopathy in mice. Neurobiol Dis 2006; 21:237-245.
17. Chieli E, Malvaldi G. Role of the microsomal FAD-containing monooxygenase in the liver toxicity of thioacetamide S-oxide. Toxicology 1984; 31:41-52.
18. Porter WR, Neal RA. Metabolism of thioacetamide and thioacetamide S-oxide by rat liver microsomes. Drug Metab Dispos 1978; 6:379-388.
19. Reddy PVB, Murthy CR, Reddanna P. Fulminant hepatic failure induced oxidative stress in nonsynaptic mitochondria of cerebral cortex in rats. Neurosci Lett 2004; 368:15-20.
20. Butterworth RF. Glutamate transporters in hyperammonemia. Neurochem Int 2002; 41:81-85.
21.Bruck R, Aeed H, Shirin H, Matas Z, Zaidel L, Avni Y, et al. The hydroxyl radical scavengers dimethylsulfoxide and dimethylthiourea protect rats against thioacetamide-induced fulminant hepatic failure. J Hepatol 1999; 31:27-38.
22. Bruck R, Aeed H, Avni Y, Shirin H, Matas Z, Shahmurov M, et al. Melatonin inhibits nuclear factor kappa B activation and oxidative stress and protects against thioacetamide induced liver damage in rats. J Hepatol 2004; 40:86-93.
23. Túnez I, Muñoz MC, Villavicencio MA, Medina FJ, de Prado EP, Espejo I, et al. Hepato-and neurotoxicity induced by thioacetamide: protective effects of melatonin and dimethylsulfoxide. Pharmacol Res 2005; 52:223-228.
24. Uskoković-Marković S, Milenković M, Topić A, Kotur-Stevuljević J, Stefanović A, Antić-Stanković J. Protective effects of tungstophosphoric acid and sodium tungstate on chemically induced liver necrosis in wistar rats. J Pharm Pharm Sci 2007; 10:340-349.
25. Anaeigoudari A, Norouzi F, Abareshi A, Beheshti F, Aaghaei A, Shafei MN, et al. Protective effects of Nigella sativa on synaptic plasticity impairment induced by lipopolysaccharide. Vet Res Forum 2018;9: 27-33.
26. Ogurlu M, Erdivanli OC, Tumkaya L, Ozgur A, Coskun ZO, Terzi S, et al. The therapeutic effect of thymoquinone on acoustic trauma-induced hearing loss in rats. Eur Arch Otorhinolaryngol 2017; 274:743-749.
27. Nagi MN, Almakki HA, Sayed-Ahmed MM, Al-Bekairi AM. Thymoquinone supplementation reverses acetaminophen-induced oxidative stress, nitric oxide production and energy decline in mice liver. Food Chem Toxicol 2010; 48:2361-2365.
28. Wilson AJ, Saskowski J, Barham W, Khabele D, Yull F. Microenvironmental effects limit efficacy of thymoquinone treatment in a mouse model of ovarian cancer. Mol Cancer 2015; 14:192-206
29. Sener U, Uygur R, Aktas C, Uygur E, Erboga M, Balkas G, et al. Protective effects of thymoquinone against apoptosis and oxidative stress by arsenic in rat kidney. Ren Fail 2016; 38:117-123.
30. Arif M, Thakur SC, Datta K. Implication of thymoquinone as a remedy for polycystic ovary in rat. Pharm Biol 2016; 54:674-685.
31. Schneider-Stock R, Fakhoury IH, Zaki AM, El-Baba CO, Gali-Muhtasib HU. Thymoquinone: fifty years of success in the battle against cancer models. Drug Discov Today 2014; 19:18-30.
32. Aycan İÖ, Tüfek A, Tokgöz O, Evliyaoğlu O, Fırat U, Kavak GÖ, et al. Thymoquinone treatment against acetaminophen-induced hepatotoxicity in rats. Int J Surg 2014; 12:213-218.
33. Nagi MN, Al-Shabanah OA, Hafez MM, Sayed-Ahmed MM. Thymoquinone supplementation attenuates cyclophosphamide-induced cardiotoxicity in rats. J Biochem Mol Toxicol 2011; 25:135-142.
34. Jaswal A, Sinha N, Bhadauria M, Shrivastava S, Shukla S. Therapeutic potential of thymoquinone against anti-tuberculosis drugs induced liver damage. Environ Toxicol Pharmacol 2013; 36:779-786.
35. Mansour MA, Nagi MN, El-Khatib AS, Al-Bekairi AM. Effects of thymoquinone on anti-oxidant enzyme activities, lipid peroxidation and DT-diaphorase in different tissues of mice: a possible mechanism of action. Cell Biochem Funct 2002; 20:143-151.
36. Nagi MN, Mansour MA. Protective effect of thymoquinone against doxorubicin–induced cardiotoxicity in rats: A possible mechanism of protection. Pharmacol Res 2000; 41:283-289.
37. Salahshoor M, Haghjoo M, Roshankhah S, Makalani F, Jalili C. Effect of Thymoquinone on Reproductive Parameter in Morphine-treated Male Mice. Adv Biomed Res 2018; 1-7.
38. Sedaghat R, Roghani M, Khalili M. Neuroprotective effect of thymoquinone, the nigella sativa bioactive compound, in 6-hydroxydopamine-induced hemi-parkinsonian rat model. Iran J Pharm Res 2014; 13:227-234.
39. Bargi R, Asgharzadeh F, Beheshti F, Hosseini M, Sadeghnia HR, Khazaei M. The effects of thymoquinone on hippocampal cytokine level, brain oxidative stress status and memory deficits induced by lipopolysaccharide in rats. Cytokine 2017; 96:173-184.
40. Abdelaziz RR, Elkashef WF, Said E. Tranilast reduces serum IL-6 and IL-13 and protects against thioacetamide-induced acute liver injury and hepatic encephalopathy. Environ Toxicol Pharmacol 2015; 40:259-267.
41.El Khiat A, El Hiba O, Aitihya M, Tamegart L, Draoui A, El Fari R, et al. Deficit of Short Working Memory in Rat With Thioacetamide-Induced Progressive Acute Hepatic Encephalopathy Involving Serotonin Innervation and Astroglia Dysfunctions. AJG 2019; 114:1-12.
42.Itoh T, Shimada Y, Terasawa K. Efficacy of Choto-san on vascular dementia and the protective effect of the hooks and stems of Uncaria sinensis on glutamate-induced neuronal death. Mech Ageing Dev 1999; 111:155-173.
43. Morris R. Developments of a water-maze procedure for studying spatial learning in the rat. J Neurosci Methods 1984; 11:47-60.
44. Paxinos G, Watson C. The rat brain in stereotaxic coordinates: hard cover edition: Elsevier; 2006.
45.Gureviciene I, Ikonen S, Gurevicius K, Sarkaki A, Van Groen T, Pussinen R, et al. Normal induction but accelerated decay of LTP in APP+ PS1 transgenic mice. Neurobiol Dis 2004; 15:188-195.
46. Lashgari R, Motamedi F, Asl SZ, Shahidi S, Komaki A. Behavioral and electrophysiological studies of chronic oral administration of L-type calcium channel blocker verapamil on learning and memory in rats. Behav Brain Res 2006; 171:324-328.
47.Sarkaki A, Farbood Y, Mansouri SMT, Badavi M, Khorsandi L, Dehcheshmeh MG, et al. Chrysin prevents cognitive and hippocampal long-term potentiation deficits and inflammation in rat with cerebral hypoperfusion and reperfusion injury. Life Sci 2019; 226:202-209.
48. Mirshekar MA, Fanaei H, Keikhaei F, Javan FS. Diosmin improved cognitive deficit and amplified brain electrical activity in the rat model of traumatic brain injury. Biomed Pharmacother 2017; 93:1220-1229.
49. Rao B, Soufir J, Martin M, David G. Lipid peroxidation in human spermatozoa as relatd to midpiece abnormalities and motility. Gamete Res 1989; 24:127-134.
50. Paoletti F, Aldinucci D, Mocali A, Caparrini A. A sensitive spectrophotometric method for the determination of superoxide dismutase activity in tissue extracts. Anal Biochem 1986; 154:536-541.
51. Forton DM, Thomas HC, Murphy CA, Allsop JM, Foster GR, Main J, et al. Hepatitis C and cognitive impairment in a cohort of patients with mild liver disease. Hepatology 2002; 35:433-439.
52. Fanoudi S, Alavi MS, Hosseini M, Sadeghnia HR. Nigella sativa and thymoquinone attenuate oxidative stress and cognitive impairment following cerebral hypoperfusion in rats. Metab Brain Dis 2019; 34:1001-1010.
53. Beheshti F, Hosseini M, Shafei MN, Soukhtanloo M, Ghasemi S, Vafaee F, et al. The effects of Nigella sativa extract on hypothyroidism-associated learning and memory impairment during neonatal and juvenile growth in rats. Nutr Neurosci 2017; 20:49-59.
54. Sayeed MSB, Asaduzzaman M, Morshed H, Hossain MM, Kadir MF, Rahman MR. The effect of Nigella sativa Linn. seed on memory, attention and cognition in healthy human volunteers. J Ethnopharmacol 2013; 148:780-786.
55. Muñoz M-D, Monfort P, Gaztelu J-M, Felipo V. Hyperammonemia impairs NMDA receptor-dependent long-term potentiation in the CA1 of rat hippocampus in vitro. Neurochem Res 2000; 25:437-441.
56. Monfort P, Muñoz MD, Felipo V. Chronic hyperammonemia in vivo impairs long-term potentiation in hippocampus by altering activation of cyclic GMP-dependent-protein kinase and of phosphodiesterase 5. J Neurochem 2005; 94:934-942.
57.França MER, Ramos RKLG, Oliveira WH, Duarte-Silva E, Araújo SMR, Los DB, et al. Tadalafil restores long-term memory and synaptic plasticity in mice with hepatic encephalopathy. Toxicol Appl Pharmacol 2019; 379:1-13.
58. Rendeiro C, Spencer JP, Vauzour D, Butler LT, Ellis JA, Williams CM. The impact of flavonoids on spatial memory in rodents: from behaviour to underlying hippocampal mechanisms. Genes Nutr 2009; 4:251-270.
59. Gressner OA, Weiskirchen R, Gressner AM. Biomarkers of liver fibrosis: clinical translation of molecular pathogenesis or based on liver-dependent malfunction tests. Clin Chim Acta 2007; 381:107-113.
60. Al-Attar AM. Hepatoprotective Influence of Vitamin C on Thioacetamide—induced Liver Cirrhosis in Wistar Male Rats. JPT 2011; 6:218-288.
61. Oguz S, Kanter M, Erboga M, Erenoglu C. Protective effects of thymoquinone against cholestatic oxidative stress and hepatic damage after biliary obstruction in rats. J Mol Histol 2012; 43:151-159.
62.Zimmermann C, Ferenci P, Pifl C, Yurdaydin C, Ebner J, Lassmann H, et al. Hepatic encephalopathy in thioacetamide-induced acute liver failure in rats: characterization of an improved model and study of amino acid-ergic neurotransmission. Hepatology 1989; 9:594-601.
63. Avraham Y, Grigoriadis N, Magen I, Poutahidis T, Vorobiav L, Zolotarev O, et al. Capsaicin affects brain function in a model of hepatic encephalopathy associated with fulminant hepatic failure in mice. Br J Pharmacol 2009; 158:896-906.
64. Avraham Y, Zolotarev O, Grigoriadis NC, Pautahidis T, Magen I, Vorobiav L, et al. Cannabinoids and capsaicin improve liver function following thioacetamide-induced acute injury in mice. Am J Gastroenterol 2008; 103:30-47.
65. Norenberg MD, Jayakumar A, Rao KR. Oxidative stress in the pathogenesis of hepatic encephalopathy. Metab Brain Dis 2004; 19:313-329.
66. Shapiro H, Ashkenazi M, Weizman N, Shahmurov M, Aeed H, Bruck R. Curcumin ameliorates acute thioacetamide-induced hepatotoxicity. J Gastroenterol Hepatol 2006; 21:358-366.
67. Fadillioglu E, Gursul C, Iraz M. Effects of caffeic acid phenethyl ester on thioacetamide-induced hepatic encephalopathy in rats. Prog Neuropsychopharmacol Biol Psychiatry 2010; 34:1440-1445.
68. Jikumaru M, Inoue M. Pathophysiology of oxystress-induced tissue damage in cerebrovascular disease. Brain Nerve 2013; 65:871-878.
69. Alzoubi KH, Khabour OF, Salah HA, Hasan Z. Vitamin E prevents high-fat high-carbohydrates diet-induced memory impairment: the role of oxidative stress. Physiol Behav 2013; 119:72-78.
70. Serrano F, Klann E. Reactive oxygen species and synaptic plasticity in the aging hippocampus. Ageing Res Rev 2004; 3:431-443.
71. Hosseini M, Mohammadpour T, Karami R, Rajaei Z, Sadeghnia HR, Soukhtanloo M. Effects of the hydro-alcoholic extract of Nigella sativa on scopolamine-induced spatial memory impairment in rats and its possible mechanism. Chin J Integr Med 2015; 21:438-444.
72. Nagi MN, Alam K, Badary OA, Al-Shabanah OA, Al-Sawaf HA, Al-Bekairi AM. Thymoquinone protects against carbon tetrachloride hetatotoxicity in mice via an anti-oxidant mechanism. Biochem Mol Biol Int 1999; 47:153-159.
73. Mladenović D, Hrnčić D, Rašić-Marković A, Stanojlović O. Behavioral and electroencephalographic manifestations of thioacetamide-induced encephalopathy: Possible mechanisms of neurotoxic effects. Arch. Biol Sci 2012; 64:829-841.
74. Rodrigo R, Cauli O, Boix J, ElMlili N, Agusti A, Felipo V. Role of NMDA receptors in acute liver failure and ammonia toxicity: therapeutical implications. Neurochem Int 2009; 55:113-118.
75. Seghatoleslam M, Alipour F, Shafieian R, Hassanzadeh Z, Edalatmanesh MA, Sadeghnia HR, et al. The effects of Nigella sativa on neural damage after pentylenetetrazole induced seizures in rats. J Tradit Complement Med 2015; 6:262-268.
76. Beheshti F, Khazaei M, Hosseini M. Neuropharmacological effects of Nigella sativa. Avicenna journal of phytomedicine 2016; 6:104. Avicenna J Phytomed 2016;6: 104-116.
77. Helal GK. Thymoquinone supplementation ameliorates acute endotoxemia-induced liver dysfunction in rats. Pak J Pharm Sci 2010; 23:131-137.