Bacopa monnieri Extract (CDRI-08) Modulates the NMDA Receptor Subunits and nNOS-Apoptosis Axis in Cerebellum of Hepatic Encephalopathy Rats

Elucidating hippocampal proteome dynamics in moderate hepatic encephalopathy rats: insights from high-resolution mass spectrometry

Hepatic encephalopathy (HE) is a debilitating neurological disorder associated with liver failure and characterized by impaired brain function. Decade-long studies have led to significant advances in our understanding of HE; however, effective therapeutic management of HE is lacking, and HE continues to be a significant cause of morbidity and mortality in patients, underscoring the need for continued research into its pathophysiology and treatment. Accordingly, the present study provides a comprehensive overview aimed at elucidating the molecular underpinnings of HE and identifying potential therapeutic targets. A moderate-grade HE model was induced in rats using thioacetamide, which simulates the liver damage observed in patients, and its impact on cognitive function, neuronal arborization, and cellular morphology was also evaluated. We employed label-free LC-MS/MS proteomics to quantitatively profile hippocampal proteins to explore the molecular mechanism of HE pathogenesis; 2175 proteins were identified, 47 of which exhibited significant alterations in moderate-grade HE. The expression of several significantly upregulated proteins, such as FAK1, CD9 and Tspan2, was further validated at the transcript and protein levels, confirming the mass spectrometry results. These proteins have not been previously reported in HE. Utilizing Metascape, a tool for gene annotation and analysis, we further studied the biological pathways integral to brain function, including gliogenesis, the role of erythrocytes in maintaining blood-brain barrier integrity, the modulation of chemical synaptic transmission, astrocyte differentiation, the regulation of organ growth, the response to cAMP, myelination, and synaptic function, which were disrupted during HE. The STRING database further elucidated the protein‒protein interaction patterns among the differentially expressed proteins. This study provides novel insights into the molecular mechanisms driving HE and paves the way for identifying novel therapeutic targets for improved disease management.

Restoration of hippocampal adult neurogenesis by CDRI-08 (Bacopa monnieri extract) relates with the recovery of BDNF-TrkB levels in male rats with moderate grade hepatic encephalopathy

Modulation of in vivo adult neurogenesis (AN) is an evolving concept in managing neurodegenerative diseases. CDRI-08, a bacoside-enriched fraction of Bacopa monnieri, has been demonstrated for its neuroprotective actions, but its effect on AN remains unexplored. This article describes the status of AN by monitoring neuronal stem cells (NSCs) proliferation, differentiation/maturation markers and BDNF-TrkB levels (NSCs signalling players) vs. the level of neurodegeneration and their modulations by CDRI-08 in the hippocampal dentate gyrus (DG) of male rats with moderate grade hepatic encephalopathy (MoHE). For NSC proliferation, 10 mg/kg b.w. 5-bromo-2'-deoxyuridine (BrdU) was administered i.p. during the last 3 days, and for the NSC differentiation study, it was given during the first 3 days to the control, the MoHE (developed by 100 mg/kg b.w. of thioacetamide i.p. up to 10 days) and to the MoHE male rats co-treated with 350 mg/kg b.w. CDRI-08. Compared with the control rats, the hippocampus DG region of MoHE rats showed significant decreases in the number of Nestin+/BrdU+ and SOX2+/BrdU+ (proliferating) and DCX+/BrdU+ and NeuN+/BrdU+ (differentiating) NSCs. This was consistent with a similar decline in BDNF+/TrkB+ NSCs. However, all these NSC marker positive cells were observed to be recovered to their control levels, with a concordant restoration of total cell numbers in the DG of the CDRI-08-treated MoHE rats. The findings suggest that the restoration of hippocampal AN by CDRI-08 is consistent with the recovery of BDNF-TrkB-expressing NSCs in the MoHE rat model of neurodegeneration.

The restoration of hippocampal nerve de-myelination by methylcobalamin relates with the enzymatic regulation of homocysteine level in a rat model of moderate grade hepatic encephalopathy

This article describes how methylcobalamin (MeCbl) restores nerve myelination in a moderate- grade hepatic encephalopathy (MoHE) model of ammonia neurotoxicity. The comparative profiles of myelin basic protein (MBP), homocysteine (Hcy) and methionine synthase (MS: a MeCbl- dependent enzyme) activity versus nerve myelination status were studied in the hippocampus of the control, the MoHE (developed by administering 100 mg/kg bw thioacetamide i.p. for 10 days) and the MoHE rats treated with MeCbl (500 µg/kg BW i.p.) for 7 days. Compared to those of control rats, the hippocampal CA1 and CA3 regions of the MoHE rats showed significantly lower myelinated areas and MBP immunostaining. This coincided with the deranged myelin layering in TEM images, decreased MBP protein and its transcript levels in hippocampus of MoHE rats. However, all these parameters recovered to normal levels after MeCbl treatment. MeCbl is a cofactor of MS that catalyzes the conversion of Hcy to methionine as a feeder step of methylation reactions. We observed significantly increased serum and hippocampal Hcy levels in MoHE rats, however, these levels were restored to control values with a concordant activation of MS due to MeCbl treatment. A significant recovery in neurobehavioral impairments in the MoHE rats due to MeCbl treatment was also observed. These findings suggest that MoHE pathogenesis is associated with deranged nerve myelination in the hippocampus and that MeCbl treatment is able to restore it mainly by activating MS, a MeCbl-dependent Hcy-metabolizing enzyme.

Therapeutic Effect of Levetiracetam Against Thioacetamide-Induced Hepatic Encephalopathy Through Inhibition of Oxidative Stress and Downregulation of NF-κB, NLRP3, iNOS/NO, Pro-Inflammatory Cytokines and Apoptosis

Hepatic encephalopathy (HE) is a serious brain disorder which associated with neurological and psychiatric manifestations. Oxidative stress and neuroinflammation and apoptosis play main roles in the development of brain damage in HE. Levetiracetam is an antiseizure drug with established antioxidant and anti-inflammatory activities. In the present study we investigated the therapeutic effects of levetiracetam against brain injury in HE and its underlying mechanisms of action. Male C57BL/6 mice were subjected to the induction of HE by the injection of thioacetamide (200 mg/kg) for 2 days. Mice were treated with levetiracetam at two doses (50 or 100 mg/kg/day) for 3 days in the treatment groups. Animals were subjected to a behavioral test and the brain tissues were dissected for histopathological, biochemical, gene expression and immunofluorescence analysis. The results showed that levetiracetam alleviated body weight loss and improved locomotor activity of mice with HE. Levetiracetam treatment decreased the histopathological changes, lipid peroxidation and protein carbonylation while restored the antioxidants (GSH, SOD and CAT) in the brain. Levetiracetam decreased the expression and activity of NF-κB, NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IFN-γ) in the brain tissue. Administration of levetiracetam inhibited iNOS/NO pathway and myeloperoxidase (MPO) activity in the brain. Moreover, caspase-3 was decreased and the ratio of Bcl2/Bax was increased in the brain of mice treated with levetiracetam. These findings suggest that levetiracetam may be a promising therapeutic agent for brain injury in HE through inhibiting the oxidative, inflammatory and apoptotic pathways.

Investigating the Neuroprotective and Cognitive-Enhancing Effects of Bacopa monnieri: A Systematic Review Focused on Inflammation, Oxidative Stress, Mitochondrial Dysfunction, and Apoptosis

The aging of the global population has increased the prevalence of neurodegenerative conditions. Bacopa monnieri (BM), an herb with active compounds, such as bacosides A and B, betulinic acid, loliolide, asiatic acid, and quercetin, demonstrates the potential for brain health. Limited research has been conducted on the therapeutic applications of BM in neurodegenerative conditions. This systematic review aims to project BM's beneficial role in brain disorders. BM has anti-apoptotic and antioxidant actions and can repair damaged neurons, stimulate kinase activity, restore synaptic function, improve nerve transmission, and increase neuroprotection. The included twenty-two clinical trials demonstrated that BM can reduce Nuclear Factor-κB phosphorylation, improve emotional function, cognitive functions, anhedonia, hyperactivity, sleep routine, depression, attention deficit, learning problems, memory retention, impulsivity, and psychiatric problems. Moreover, BM can reduce the levels of pro-inflammatory biomarkers and oxidative stress. Here, we highlight that BM provides notable therapeutic benefits and can serve as a complementary approach for the care of patients with neurodegenerative conditions associated with brain disorders. This review adds to the growing interest in natural products and their potential therapeutic applications by improving our understanding of the mechanisms underlying cognitive function and neurodegeneration and informing the development of new therapeutic strategies for neurodegenerative diseases.

Carvedilol attenuates brain damage in mice with hepatic encephalopathy

Brain injury is the most common and serious consequence of hepatic encephalopathy (HE), and its pathophysiology is poorly understood. Excessive inflammatory, oxidative and apoptotic responses are the major mechanisms involved in the progression of brain injury induced by HE. Carvedilol is an adrenergic receptor antagonist with pronouncedantioxidant and anti-inflammatory activity. The present study aimed to investigatethe effects and underlying mechanisms of carvedilol on HE-induced brain damage in mice. Experimental model of HE was induced by the injection of thioacetamide (200 mg/kg) for two consecutive days and then mice were treated with carvedilol (10 or 20 mg/kg/day, orally) for 3 days in treatment groups. After the behavioral test, animals were sacrificed and the brain tissues were collected for biochemical, real time PCR and immunohistochemical analysis. The results showed that carvedilol improved locomotor impairment and reduced mortality rate in mice with HE. Carvedilol treatment decreased the brain levels of oxidative stress markers and induced Nrf2/HO-1 pathway. Carvedilol inhibited the activity of nuclear factor kappa B (NF-κB) and the expression of pro-inflammatory cytokines TNF-α, IL1β and IL-6 in the brain tissues. Treatment of mice with carvedilol caused a significant reduction in the brain levels of iNOS/NO, myeloperoxidase (MPO), cyclooxygenase (COX)-2 and chemokine MCP-1 as proinflammatory mediators in HE. Moreover, the ratio of Bcl2/Bax was increased and apoptotic cell death was decreased in the brain of mice treated with carvedilol. In conclusion, carvedilol exerted protective effect against HE-induced brain injury through increasing antioxidant defense mechanisms and inhibitionof inflammatory and apoptotic pathways.

Sirtuin-3 activation by honokiol restores mitochondrial dysfunction in the hippocampus of the hepatic encephalopathy rat model of ammonia neurotoxicity

The neurotoxic level of ammonia in the brain during liver cirrhosis causes a nervous system disorder, hepatic encephalopathy (HE), by affecting mitochondrial functions. Sirtuin-3 (SIRT3) is emerging as a master regulator of mitochondrial integrity, which is currently being focused as a pathogenic hotspot for HE. This article describes SIRT3 level versus mitochondrial dysfunction markers in the hippocampus of the control, the moderate-grade hepatic encephalopathy (MoHE), developed in thioacetamide-induced (100 mg/kg bw ip for 10 days) liver cirrhotic rats, and the MoHE rats treated with an SIRT3 activator, honokiol (HKL; 10 mg/kg bw ip), for 7 days from 8th day of the thioacetamide schedule. As compared with the control group rats, hippocampus mitochondria of MoHE rats showed a significant decline in SIRT3 expression and its activity with concordant enhancement of ROS and declined membrane permeability transition and organelle viability scores. This was consistent with the declined mitochondrial thiol level and thiol-regenerating enzyme, isocitrate dehydrogenase 2. Also, significantly declined activities of electron transport chain complexes I, III, IV, and Q₁₀ , decreased NAD⁺ /NADH and ATP/AMP ratios, and enhanced number of the shrunken mitochondria were recorded in the hippocampus of those MoHE rats. However, all these mitochondrial aberrations were observed to regain their normal profiles/levels, concordant to the enhanced SIRT3 expression and its activity due to treatment with HKL. The findings suggest a role of SIRT3 in mitochondrial structure-function derangements associated with MoHE pathogenesis and SIRT3 activation by HKL as a relevant strategy to protect mitochondrial integrity during ammonia neurotoxicity.

Standardized Bacopa monnieri Extract Ameliorates Learning and Memory Impairments through Synaptic Protein, Neurogranin, Pro-and Mature BDNF Signaling, and HPA Axis in Prenatally Stressed Rat Offspring

Prenatal stress (PNS) influences offspring neurodevelopment, inducing anxiety-like behavior and memory deficits. We investigated whether pretreatment of Bacopa monnieri extract (CDRI-08/BME) ameliorates PNS-induced changes in signaling molecules, and changes in the behavior of Wistar rat offspring. Pregnant rats were randomly assigned into control (CON)/prenatal stress (PNS)/PNS and exposed to BME treatment (PNS + BME). Dams were exposed to stress by placing them in a social defeat cage, where they observed social defeat from gestational day (GD)-16–18. Pregnant rats in the PNS + BME group were given BME treatment from GD-10 to their offspring’s postnatal day (PND)-23, and to their offspring from PND-15 to -30. PNS led to anxiety-like behavior; impaired memory; increased the level of corticosterone (CORT), adrenocorticotropic hormone, glucocorticoid receptor, pro-apoptotic Casepase-3, and 5-HT_2C receptor; decreased anti-apoptotic Bcl-2, synaptic proteins (synaptophysin, synaptotagmin-1), 5-HT_1A, receptor, phosphorylation of calmodulin-dependent protein kinase II/neurogranin, N-methyl-D-aspartate receptors (2A,2B), postsynaptic density protein 95; and conversion of pro and mature brain derived neurotropic factor in their offspring. The antioxidant property of BME possibly inhibiting the PNS-induced changes in observed molecules, anxiety-like behavior, and memory deficits. The observed results suggest that pretreatment of BME could be an effective coping strategy to prevent PNS-induced behavioral impairments in their offspring.

SIRT1 activation by resveratrol reverses atrophy of apical dendrites of hippocampal CA1 pyramidal neurons and neurobehavioral impairments in moderate grade hepatic encephalopathy rats

A preliminary observation about resveratrol (RSV) dependent normalization of inflammatory and apoptotic factors in the cortex of hyperammonemic rat model of moderate grade hepatic encephalopathy (MoHE) led us to evaluate whether RSV is ultimately able to confer neuroprotection against MoHE pathogenesis and that it does so by activating its bonafide molecular target SIRT1. The present study compared the profile of relevant neurobehavioral pattern vs neuromorphometry of hippocampal CA1 neurons and SIRT1 activity in the hippocampus of the chronic liver failure (CLF) model of moderate grade HE (MoHE) rats induced by administration of 100 mg/kg body weight of thioacetamide i.p. for 10 days and in the CLF/MoHE rats treated with 10 mg/kg body weight RSV i.p. for 7 days. As compared to the control group rats, the MoHE rats showed significantly deranged pattern of memory and motor functions on MWM and rota rod tests, respectively. These behavioural deficits were associated with a significant reduction in apical dendrite length and number of branching points in the CA1 pyramidal neurons. Interestingly, all these parameters were found to be recovered back to their normal levels in the MoHE rats treated with RSV. Concordantly, MoHE associated declined SIRT1 activity in the hippocampus could be normalized back due to RSV treatment to those MoHE rats. Our findings suggest that RSV is able to normalize MoHE associated memory impairments and motor deficits vis a vis reversal of CA1 dendritic atrophy via SIRT1 activation.

Insights Into the Molecular Aspects of Neuroprotective Bacoside A and Bacopaside I

Bacopa monnieri, commonly known as Brahmi, has been extensively used as a neuromedicine for various disorders such as anxiety, depression and memory loss. Chemical characterization studies revealed the major active constituents of the herb as the triterpenoid saponins, bacosides. Bacoside A, the vital neuroprotective constituent, is composed of four constituents viz., bacoside A3, bacopaside II, jujubogenin isomer of bacopasaponin C (bacopaside X) and bacopasaponin C. B. monnieri extracts as well as bacosides successfully establish a healthy antioxidant environment in various tissues especially in the liver and brain. Free radical scavenging, suppression of lipid peroxidation and activation of antioxidant enzymes by bacosides help to attain a physiological state of minimized oxidative stress. The molecular basis of neuroprotective activity of bacosides is attributed to the regulation of mRNA translation and surface expression of neuroreceptors such as AMPAR, NMDAR and GABAR in the various parts of the brain. Bioavailability as well as binding of neuroprotective agents (such as bacosides) to these receptors is controlled by the Blood Brain Barrier (BBB). However, nano conversion of these drug candidates easily resolves the BBB restriction and carries a promising role in future therapies. This review summarizes the neuroprotective functions of B. monnieri extracts as well as its active compounds (bacoside A, bacopaside I) and the molecular mechanisms responsible for these pharmacological activities.