Erythropoietin ameliorates the motor and cognitive function impairments in a rat model of hepatic cirrhosis

Epoetin alfa has a potent anxiolytic effect on naive female rats

BACKGROUND

Epoetin alfa is a derivative of the erythropoietin hormone. This study aims to investigate the epoetin alfa effect on anxiety-like behaviors.

METHODS

Adult female Wistar Albino rats were divided into Control (n = 8), 1000 U Epoetien alfa, and 2000 U Epoetien alpha. Epoetin alfa was administered intraperitoneally once a week for 4 weeks. The animals were then subjected to open field test, elevated plus maze, light-dark box, and the behaviors were video recorded.

RESULTS

Epoetin alfa significantly reduced anxiety-like behaviors in both low- and high-dose groups in a dose-independent manner. This anxiolytic effect was seen in all three anxiety tests. Further, exploratory behaviors such as unsupported rearing and head-dipping behaviors increased with the application of Epoetin alfa. This protocol did not alter locomotor activity.

CONCLUSION

The present study found beneficial effects of epoetin alfa on behaviors. Further studies on the effect of derivatives of erythropoietin hormone on anxiety-like behaviors are needed.

Hepatoprotective and neuroprotective effects of quinacrine against bile duct ligation-induced hepatic encephalopathy in rats: Role of bone morphogenetic proteins signaling

AIMS

This study aimed to assess the potential protective effect of quinacrine, an FDA approved antimalarial drug with reported anti-inflammatory effects, on hepatic encephalopathy (HE) in a bile duct ligation (BDL) experimental model and to investigate the mechanisms responsible for this effect, namely those associated with the liver-brain axis, particularly, bone morphogenetic protein 2 (BMP2) signaling.

MATERIALS AND METHODS

Five groups of rats were selected at random: sham, BDL, (BDL+ quinacrine 5), (BDL+ quinacrine 10), and (quinacrine 10 + sham). Daily Intraperitoneal (I.P.) administration of quinacrine was initiated on the surgery day and continued for 28 days.

KEY FINDINGS

Results showed that rats that underwent BDL exhibited marked elevation of serum liver enzymes, ammonia, total bilirubin, together with oxidative stress, inflammation, dysregulated farnesoid x receptor (FXR), dysregulated BMP2 signaling and escalated fibrotic markers indicating hepatotoxicity, cholestasis and fibrosis. Besides, neurotoxicity was detected as manifested by cognitive deficits and dysregulation of hippocampal FXR, BMP2 signaling, WNT3A signaling, brain derived neurotrophic factor (BDNF), phospholipase A2 (PLA2) and glial fibrillary acidic protein (GFAP). In contrast, co-treatment with quinacrine mitigated BDL-induced hepatotoxicity, cholestasis, fibrosis, and neurotoxicity. Notably, quinacrine improved learning and memory and restored FXR, BMP2 signaling in the liver and hippocampus. In addition, quinacrine restored hippocampal WNT3A signaling, BDNF, whereas it downregulated expression of hippocampal PLA2 and GFAP.

SIGNIFICANCE

These findings demonstrated implication of BMP2 signaling in the molecular process of BDL-induced HE and proposed that quinacrine has potential hepatoprotective and neuroprotective properties against HE.

Anti-inflammatory strategies for hepatic encephalopathy: preclinical studies

Hepatic encephalopathy (HE) is a potentially reversible neuropsychiatric syndrome. Often, HE causes cognitive and motor dysfunctions due to an acute or chronic insufficiency of the liver or a shunting between the hepatic portal vein and systemic vasculature. Liver damage induces peripheral changes, such as in the metabolism and peripheral inflammatory responses that trigger exacerbated neuroinflammation. In experimental models, anti-inflammatory strategies have demonstrated neuroprotective effects, leading to a reduction in HE-related cognitive and motor impairments. In this scenario, a growing body of evidence has shown that peripheral and central nervous system inflammation are promising preclinical targets. In this review, we performed an overview of FDA-approved drugs and natural compounds which are used in the treatment of other neurological and nonneurological diseases that have played a neuroprotective role in experimental HE, at least in part, through anti-inflammatory mechanisms. Despite the exciting results from animal models, the available data should be critically interpreted, highlighting the importance of translating the findings for clinical essays.

Peroxisome proliferator-activated receptor-γ doesn't modify altered electrophysiological properties of the CA1 pyramidal neurons in a rat model of hepatic cirrhosis

Regarding the low quality of life due to the cognitive complications in the patients with hepatic cirrhosis (HC), the goal of this study was to examine the possible neuroprotective effect of pioglitazone (PIO) on the electrophysiological alterations of hippocampus, a major area of cognition, in the experimental model of bile duct ligation (BDL). We used adult male Wistar rats in the present study to perform BDL or sham surgery. Pioglitazone was administered in BDL rats two weeks after the surgery for the next continuous four weeks. The effects of pioglitazone on BDL-induced electrophysiological alterations of the CA1 pyramidal neurons in the hippocampus were evaluated by whole-cell patch clamp recordings. Our findings demonstrated that chronic administration of PIO could not reverse the electrophysiological changes in the CA1 pyramidal neurons of the hippocampus in BDL rats but could improve the hepatic dysfunction.Together, the results of this study suggest that PIO administration cannot counteract altered intrinsic properties of the hippocampal neurons which has been shown recently as an involved mechanism of the cognitive impairments in hepatic encephalopathy (HE).

Erythropoietin attenuates locomotor and cognitive impairments in male rats subjected to physical and psychological stress

Physical and cognitive problems associated with stress are believed to result from stress-related damage to neurons involved in motor and cognitive control. In general, there are two types of stress, physical and psychological which both negatively impact neuronal function. Erythropoietin (EPO) has been shown to exert a neuroprotective effect in various models of physical brain injury; however, its actions on stress-related changes in behavior are unknown. The aim of the current study was to determine whether EPO ameliorated stress-induced locomotor and cognitive impairments, and to compare the effects of EPO on behavioral changes induced by the two different types of stressors. In this study, male Wistar rats were randomly divided into five groups and placed under physical or psychological stress for 10 consecutive days while erythropoietin was injected intraperitoneally (i.p.) every other day (500 U/kg/i.p.) 30 min before stress induction. Exploratory, anxiety-related behaviors, learning and memory were assessed by using open field, plus maze and Morris Water Maze (MWM) tests respectively. Our data showed physical and psychological stress induced dysfunction in locomotion, reduced explorative skills, heightened anxiety-like behavior and reduced memory, which could be partly reversed by EPO. We conclude that EPO reduces adverse effects of both psychological and physical stress, putatively through protection of locomotor and cognitive-controlling neurons vulnerable to the damaging effects of stress. However, future studies need to elucidate the neural mechanisms of the protective effects of EPO.

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Anxiety like behavior and spatial memory impaired in stress-exposed rats.

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Physical and Psychological stress had the same impact on behavioral function

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EPO could improve memory retrieval and lessen anxiety-like behaviors

Time dependent alteration of locomotor behavior in rat with acute liver failure induced cerebellar neuroinflammation and neuro-astroglial damage

Hepatic encephalopathy (HE) is a neurophysiological syndrome secondary to acute or chronic liver failure. Studies showed that HE patients exhibit a deficit in motor coordination, which may result from cerebellar functional impairment. The aim of this study is to assess the time-dependent alteration of locomotor behavior and the glial and neuronal alteration in rat with acute HE induced chemically. The study was carried out in male Sprague-Dawley rats with thioacetamide (TAA) induced acute liver failure at different stages 12 h, 24 h and 36 h. Hepatic and renal functions were assessed via various biochemical and histopathological examinations, while the cerebellum and the midbrain were examined using histology and immunohistochemistry for tyrosine hydroxylase (TH), cyclooxygenase-2 (COX-2) and glial fibrillary acidic protein (GFAP). We used as well, the open field test and the Rotarod test for assessing the locomotor activity and coordination. Our data showed a progressive loss of liver function and a progressive alteration in locomotor behavior and motor coordination in acute HE rats. In the cerebellum, we noted an increase in the degeneration of cerebellar Purkinje neurons parallel to increased COX-2 immunoreactivity together with astrocytic morphology and density changes. Likewise, in substantia nigra pars compacta, TH levels were reduced. We showed through the current study, a progressive deterioration in locomotor behavior in acute HE rats, as a result of Purkinje neurons death and a deficient dopaminergic neurotransmission, together with the morpho-functional astroglial modifications involving the oxidative stress and neuroinflammation.

Estrogen attenuates physical and psychological stress-induced cognitive impairments in ovariectomized rats

INTRODUCTION

Women are more vulnerable to stress-related disorders than men, which is counterintuitive as female sex hormones, especially estrogen, have been shown to be protective against stress disorders.

METHODS

In this study, we investigated whether two different models of stress act differently on ovariectomized (OVX) rats and the impact of estrogen on physical or psychological stress-induced impairments in cognitive-behaviors. Adult female Wistar rats at 21-22 weeks of age were utilized for this investigation. Sham and OVX rats were subjected to physical and psychological stress for 1 hr/day for 7 days, and cognitive performance was assessed using morris water maze (MWM) and passive avoidance (PA) tests. The open field and elevated plus maze tests (EPM) evaluated exploratory and anxiety-like behaviors.

RESULTS

In sham and OVX rats, both physical and psychological stressors were associated with an increase in EPM-determined anxiety-like behavior. OVX rats exhibited decreased explorative behavior in comparison with nonstressed sham rats (p < .05). Both physical stress and psychological stress resulted in disrupted spatial cognition as assayed in the MWM (p < .05) and impaired learning and memory as determined by the PA test when the OVX and sham groups were compared with the nonstressed sham group. Estrogen increased explorative behavior, learning and memory (p < .05), and decreased anxiety-like behavior compared with vehicle in OVX rats exposed to either type of stressor.

CONCLUSIONS

When taken together, estrogen and both stressors had opposite effects on memory, anxiety, and PA performance in a rat model of menopause, which has important implications for potential protective effects of estrogen in postmenopausal women exposed to chronic stress.

Effects of erythropoietin on bile duct ligation-induced neuro-inflammation in male rats

Hepatic encephalopathy (HE) is a brain disorder as a result of liver failure. Previous studies have indicated that erythropoietin (EPO) has neuroprotective effects in different neurological diseases. This study addressed the therapeutic effect of a four-week treatment with EPO on neuronal damages in bile duct-ligated rats. Forty male Wistar rats (250-280 g) were used in the present study. The animals were randomly divided into four groups consisting of 10 animals each, including sham, sham + EPO, bile duct ligation (BDL), and BDL + EPO. EPO was intraperitoneally administered every other day (5,000 U/Kg) in the last four weeks after BDL. Biochemical and histological studies were performed to evaluate neurodegeneration. The results revealed that BDL increases the level of hepatic enzymes and total bilirubin. Furthermore, neurodegeneration was significantly increased in the BDL group compared to sham groups. EPO preserved hepatic enzymes and total bilirubin in the treated group. In addition, EPO significantly decreased the neurodegeneration in BDL + EPO compared to the BDL group. Results of this study showed that EPO has neuroprotective effects in the rat model of HE, possibly due to its anti-inflammatory and anti-oxidant properties. Complementary studies are required to clarify the exact mechanisms.

Inhibition of inflammation is not enough for recovery of cognitive impairment in hepatic encephalopathy: Effects of minocycline and ibuprofen

There is evidence that hyperammonia and inflammation play crucial roles in hepatic encephalopathy. This study intends to determine neuroprotective effects of minocycline (MINO) and ibuprofen (IBU), and also set out to assess whether inhibition of inflammation is enough to achieve optimal improvement of hepatic encephalopathy symptoms. The hepatic encephalopathy was induced by bile-duct ligation (BDL), and the animals received first dose of MINO and/or IBU 15 days later and then every day until the 28 day. The rats were divided into the 6 groups of control, sham, BDL + V and BDL + IBU, BDL + MINO and BDL + MINO + IBU, which each group had 3 sub-groups for evaluations of blood-brain barrier (BBB), memory performance, synaptic-plasticity and apoptosis. The long-term potentiation (LTP) and short-term potentiation were evaluated by field potential recording. The memory performance, apoptosis and BBB integrity were assessed via passive avoidance, Western-blotting of caspase-3 and Evans-blue dye extravasation, respectively. The MINO, IBU or their co-treatment in the BDL rats did not improve liver dysfunction. The BDL increased hippocampal apoptosis and BBB disruption, which were fully recovered by all three pharmacological interventions. The MINO treatment alone or combined with IBU had similar neuroprotective effects on the BDL-induced disturbances of hippocampal basal synaptic transmission, LTP and memory performance, whereas they were not ameliorated by the single IBU therapy. Therefore, it seems likely that inhibition of inflammation is not able to improve functionally impaired memory and LTP in the hepatic encephalopathy, and they may be recovered by the direct neuroprotective effects of the MINO.

Evidence of Altered Trigeminal Nociception in an Animal Model of Fibromyalgia

Objective

Fibromyalgia (FM) is a debilitating chronic condition that significantly affects quality of life. A strong association has been demonstrated between FM and chronic pain in the trigeminal region in clinical studies. This study was performed to evaluate the response to acute and chronic noxious stimuli applied to the facial region.

Methods

Adult male Wistar rats (250-270 g, N = 10 for each group) were used in the current study. A subchronic swim stress model was used as the animal model of FM. Anxiety-like behaviors and response to acute and chronic noxious stimuli were assayed using the elevated plus maze, eye wiping test, and orofacial formalin test, respectively. Balance and motor function were evaluated using rotarod and wire grip tests.

Results

An increased anxiety-like behavior was observed in swim stress rats in comparison with control and sham subjects. Response to acute and chronic noxious stimuli in the trigeminal region was increased in the stressed rats. Motor and balance function were not altered following stress.

Conclusions

Results of the current study demonstrated a hyperalgesic state in the trigeminal region in a possible animal model of FM. This study provides a reliable animal model for further research on the possible mechanisms of orofacial pain in FM.

Peroxisome proliferator-activated receptor-γ activation attenuates harmaline-induced cognitive impairments in rats

Cognitive and motor disturbances are serious concerns of the tremors induced by motor disorders. Despite the lack of effective clinical treatment, some potential therapeutic agents have been used to alleviate the cognitive symptoms in the animal models of tremor. Recent studies have shown that PPAR-γ agonists have neuroprotective effects. In the current study, the effects of pioglitazone (PIO), a peroxisome proliferator-activated receptor gamma agonist, on harmaline-induced motor and cognitive impairment were studied. Male Wistar rats were divided into vehicle (normal saline), PIO (20 mg/kg i.p.), harmaline (10 mg/kg, i.p.) and PIO + harmaline (PIO injected 2 h before harmaline) groups. Open field, rotarod, wire grip, foot print and Morris water maze tests were used to evaluate the motor and cognitive performance. The results indicated that administration of PIO attenuated harmaline-induced locomotor, anxiety-like behaviors, and spatial learning and memory impairments, but it partially decreased the tremor score. The neuroprotective and anxiolytic effects of PIO demonstrated in the current study can offer the PPAR-γ receptor agonism as a potential therapeutic agent in the treatment of patients with tremor that manifest mental dysfunction.

Characterization of the CA1 pyramidal neurons in rat model of hepatic cirrhosis: insights into their electrophysiological properties

Although the key contributors of altering neurological function in hepatic encephalopathy are relatively well known, the electrophysiological mechanism of CA1 damage, a key vulnerable area during hyperammonemia, have not yet been defined. Therefore, here we focus on the electrophysiological mechanisms of cognitive impairments following bile duct ligation (BDL). We performed patch-clamp recordings from the CA1 pyramidal neurons in hippocampus of male Wistar rats, which underwent sham or BDL surgery. A striking electrophysiological change of hippocampal neurons in experimental model of BDL was observed in the present study. Spontaneous firing frequency and rate of action potential (AP) rebound was decreased and afterhyperpolarization amplitude (AHP) was increased significantly in hippocampal cells of BDL animals compared to sham group. Together, the results suggest that altered intrinsic properties of the hippocampal neurons may contribute to the cognitive abnormalities during hepatic encephalopathy (HE), highlighting the electrophysiological mechanisms for providing new treatments against HE.

Nitric oxide pathway presumably does not contribute to antianxiety and memory retrieval effects of losartan

Nitric oxide (NO) and angiotensin (AT) receptors have demonstrated well-established interactions in various physiological phenomena. AT1 receptors can play a part in stress-induced activation of the hypothalamic-pituitary-adrenal axis; also, angiotensinergic neurotransmission plays a pivotal role in stress-evoked physiological responses. On the basis of the stress-modulating characteristics of NO, AT1, and AT2 receptors, the present study evaluated the roles of NO and AT1 receptors in the attenuation of stress-induced anxiety-like behaviors after administration of losartan, an AT1 antagonist. Male Wistar rats were exposed to the communication stress box, using a novel method to induce physical or emotional stress, and losartan (10 mg/kg), losartan+L-NG-nitroargininemethyl ester (L-NAME), L-NAME (1, 10, and 100 mg/kg), and normal saline-treated groups were compared. Losartan had reduced behavioral changes induced by both types of stressor and enhanced memory retrieval. Anxiety-like behaviors were significantly attenuated by administration of losartan, to a greater extent in the emotional rather than physical stress group. None of the injected dosages of L-NAME reversed the antianxiety and memory retrieval effects of losartan. Our results indicate that losartan probably improves memory retrieval and lessens anxiety-like behaviors through mechanisms other than the NO pathway.

Evaluation of prepulse inhibition and memory impairments at early stage of cirrhosis may be considered as a diagnostic index for minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE), which represents the early stage of this condition, is not clinically apparent and is prevalent in up to 80% of patients. The poor outcomes of MHE encouraged us to identify more simple methods for early diagnosis of MHE. To this purpose, we evaluated the contemporary manifestations of motor, cognitive and sensorimotor gaiting deficits following bile duct-ligation (BDL). Male Wistar rats were undergone BDL to induce cirrhosis and locomotor, spatial learning and memory and sensorimotor gating were assessed 2, 3, and 4weeks after the operation by rotarod, Morris water-maze and prepulse inhibition (PPI) tests. PPI was examined 6weeks after BDL until appearance of hepatic encephalopathy. Results showed that although PPI was significantly enhanced in the 6-week BDL animals, locomotor activity reduced in 4-week BDL rats compared to the BDL rats after a 2-week period. The total distance travelled and swimming time to reach the platform increased in the 4-week BDL rats and, in contrast, the percentage of time spent and space travelled in correct quadrant decreased. Moreover, memory index decreased in the 3-week BDL group compared to sham-operated group. It was observed an increase in global PPI in 3- and 4-week BDL animals in comparison with either 2-week BDL or sham-operated rats. Consequently, it is indicated that BDL animals manifest spatial learning and memory deficits and PPI disruption in early stage of HE and evaluation of these factors can be considered as indices for simple and early diagnosis of MHE.

The effect of Elettaria cardamomum extract on anxiety-like behavior in a rat model of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition which develops in 6-8% of the general population. Current standard pharmacological treatments for PTSD cannot be widely used due to having various side effects. Nowadays, various pharmacological properties have been related to Elettaria cardamomum L. (family of Zingiberaceae). The present study aims to evaluate the efficacy of E. cardamomum methanolic extract on anxiety-like behavior in a rat model of PTSD. Adult male Wistar rats (200-250gr) were used in this study. The rats underwent single prolonged stress (SPS) or control and intraperitoneally received either saline or different dosages (200, 400, and 800mg/kg) of E. cardamomum methanolic extract before and after stress sessions. Moreover, open field, elevated plus-maze, and rotarod tests were used to evaluate locomotion and anxiety-like behavior in the rats. Findings demonstrated that E. Cardamomum methanolic extract, particularly at the dose of 400mg/kg, significantly (P<0.05) improved anxiety-like behavior in a rat model of PTSD, as examined by the open field, elevated plus-maze, and rotarod tests. Administration of E. cardamomum methanolic extract after stress might help to prevent the formation of anxiety-like behavior in the animals. However, further studies are requiredto clarify the exact mechanisms involved.

The possible association between Toxoplasma gondii infection and risk of anxiety and cognitive disorders in BALB/c mice

There are conflicting reports concerning the association of Toxoplasma gondii infection with increased risk of mental disorders. This investigation will provide a good understanding about defining the possible association between T. gondii exposure and risk of anxiety and cognitive alterations. Besides, a secondary objective of this study was to determine the effect of pioglitazone administration on the possible alterations induced by T. gondii exposure. Male BALB/c mice were used for this study. The animal model of Toxoplasma infection was established by the intraperitoneal inoculation of 20-25 tissue cysts from Tehran strain of T. gondii. Pioglitazone (20 mg/kg, i.p.1/day) was administered to the animals for 2 weeks before behavioural tests. Behavioural tests including open-field, elevated plus-maze and passive avoidance learning were evaluated in the groups. Since cytokines were implicated as a contributing factor for mood disorders, the mRNA levels of TNF-α, IL-1β, IL-6 as well as inducible nitric oxide synthase (iNOs) were examined by real-time PCR. Findings demonstrated that T. gondii caused anxiety-like symptoms and impaired cognitive functions of the infected BALB/c mice, whereas pioglitazone, a peroxisome proliferator-activated receptor agonist, showed a promising effect against the cognitive impairments induced by Toxoplasma infection. The results also revealed that the mRNA levels of the aforementioned cytokines were significantly (p < 0.05) increased in the infected mice compared to the uninfected BALB/c ones. Pioglitazone can be offered as a potential neuroprotective agent in the treatment of patients with T. gondii infection that manifests anxiety and cognitive impairments; however, further studies are needed to clarify the exact mechanisms.

Polycythemia is associated with bone loss and reduced osteoblast activity in mice

Increased fragility has been described in humans with polycythemia vera (PV). Herein, we describe an osteoporotic phenotype associated with decreased osteoblast activity in a mouse model of PV and another mouse of polycythemia and elevated circulating erythropoietin (EPO). Our results are important for patients with PV or those treated with recombinant EPO (rEPO).

INTRODUCTION

PV and other myeloproliferative syndromes have been recently associated with an increased risk for fractures. However, the presence of osteoporosis in these patients has not been well documented. EPO, a hormone primarily known to stimulate erythropoiesis, has been shown recently to regulate bone homeostasis in mice. The aim of this study was to examine the bone phenotype of a mouse model of PV and compare it to that of animals with polycythemia caused by elevated circulating EPO.

METHODS

Bone mass and remodeling were evaluated by micro-computed tomography and histomorphometry. The JAK2(V617F) knock-in mouse, a model of human PV, manifests polycythemia and low circulating EPO levels. Results from this mouse were compared to wild type (wt) controls and the tg6 transgenic mouse that shows polycythemia caused by increased constitutive expression of EPO.

RESULTS

Compared to wt, both JAK2(V617F) and tg6 mice had a decrease in trabecular bone mass. Tg6 mice showed an additional modest decrease in cortical thickness and cortical bone volume per tissue volume (P < 0.01) suggesting a more severe bone phenotype than JAK2(V617F). Decreased osteoblast numbers and bone formation along with normal osteoclast numbers and activity were found in both mice.

CONCLUSIONS

This study indicates that PV is associated with low bone mass and decreased osteoblast activity in mice. Our results support future studies of osteoporosis in affected humans. Polycythemia caused by chronically elevated circulating EPO also results in bone loss, and implications on patients treated with rEPO should be evaluated.