Naringenin mitigates reserpine-induced anxiety-like behavior, neurodegeneration, and oxidative stress in male rats.

Reserpine (Res) induces anxiety-like behaviors, orofacial dyskinesia, and neurodegeneration in animals, the pathophysiology of which has been related to oxidative stress. The purpose of this study was to investigate whether naringenin (NG) could prevent reserpine-induced anxiety-like behaviors, orofacial dyskinesia, and neurodegeneration in male rats. Twenty-eight male rats were distributed into different groups as follows: Control rats; vehicle rats, which received the vehicles (normal saline, orally; acetic acid, intraperitoneally); Res rats (1 mg/kg/day) every other day for 3 days; and Res + NG rats, which received NG (50 mg/kg, orally, pre-treatment for 7 days), followed by Res. Administration of Res significantly increased chewing frequency compared with the control group (P < 0.01) and NG reversed the effect of Res on this factor (P < 0.05). Res induced an anxiety-like behavior in rats in the plus maze, and pre-treatment with NG improved this behavior. In addition, Res significantly increased the level of oxidative stress markers and degenerated neurons in the striatum; NG was able to ameliorate these damages. The results of this study demonstrated that Res caused behavioral disorders and increased the levels of oxidative stress in male rats; the use of NG was effective in treating these disorders. Therefore, NG should be considered as a preventive agent for reserpine-induced brain damage in male rats.

The effect of gallic acid on memory and anxiety-like behaviors in rats with bile duct ligation-induced hepatic encephalopathy: Role of AMPK pathway.

Objective: Hepatic encephalopathy (HE) is a serious neurological syndrome which is caused by acute and chronic liver diseases. In this study, the effect of gallic acid (GA) as an activator of AMP-activated protein kinase (AMPK) on memory and anxiety-like behaviors in rats with HE caused by bile duct ligation (BDL) was investigated. Materials and Methods: The rats were randomly divided into the following eight groups (n=7): sham; BDL; BDL+GA 20 mg/kg; BDL+GA 30 mg/kg; sham+dorsomorphin or compound C (CC) (as AMPK inhibitors); BDL+CC; BDL+GA 20 mg/kg+CC; and BDL+GA 30 mg/kg+CC. The rats received GA once daily by gavage for four weeks, and dorsomorphin 6.2 µg per rat was administered on a daily basis via bilateral intraventricular injection for four weeks. Behavioral tests including novel object recognition (NOR), open field and Morris water maze (MWM) were used to evaluate anxiety and memory in the rats. Results: Examining some parameters of NOR and MWM tests showed that memory performance was significantly reduced in the BDL versus the sham group, and in the BDL+CC versus the sham+CC group (p<0.05). GA intake improved memory in the GA-receiving groups compared with the BDL and BDL+CC groups (p<0.05). Examining some parameters of open field test showed that anxiety was significantly increased in the BDL versus the sham group, and the BDL+CC versus the sham+CC group (p<0.05). GA intake reduced anxiety in GA-receiving groups compared with the BDL+BDL+CC group (p<0.05). Conclusion: GA was effective in improving cognitive and anxiety-like behaviors through activating AMPK.

Histamine H3 receptor antagonist, ciproxifan, alleviates cognition and synaptic plasticity alterations in a valproic acid-induced animal model of autism.

RATIONALE: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and cognitive behaviors. Histamine H3 receptor (H3R) antagonists are considered as therapeutic factors for treating cognitive impairments. OBJECTIVES: The aim of the present study was to evaluate the effects of the H3R antagonist, ciproxifan (CPX), on cognition impairment especially, spatial learning memory, and synaptic plasticity in the CA1 region of the hippocampus in autistic rats. METHODS: Pregnant rats were injected with either valproic acid (VPA) (600 mg/kg, i.p.) or saline on an embryonic day 12.5 (E12.5). The effects of the H3R antagonist, ciproxifan (CPX) (1, 3 mg/kg, i.p.), were investigated on learning and memory in VPA-exposed rat pups and saline-exposed rat pups using Morris water maze (MWM) and social interaction tasks. The H2R antagonist, famotidine (FAM) (10, 20, 40 mg/kg, i.p.), was used to determine whether brain histaminergic neurotransmission exerted its procognitive effects through the H2R. In addition, synaptic reinforcement was evaluated by in vivo field potential recording. RESULTS: The results showed that VPA-exposed rat pups had significantly lower sociability and social memory performance compared to the saline rats. VPA-exposed rat pups exhibited learning and memory impairments in the MWM task. In addition, VPA caused suppression of long-term potentiation (LTP) in the CA1 area of the hippocampus. Our results demonstrated that CPX 3 mg/kg improved VPA-induced cognitive impairments and FAM 20 mg/kg attenuated cognitive behaviors as well as electrophysiological properties. CONCLUSIONS: CPX 3 mg/kg improved VPA-induced impairments of LTP as well as learning and memory deficits through H2R.

Promising Effects of Naringenin and Melatonin against Hepatic Encephalopathy Impairments Induced by Bile Duct Ligation in Male Rats.

BACKGROUND: Bile duct ligation (BDL) is used for evaluating the protective effects of different agents with anti-inflammatory and antioxidant properties against the liver and brain damages. Naringenin (N) and melatonin (M) are used as protectants in various models of diseases. AIMS: In the current research, the combinational effects of these well-known anti-inflammatory and antioxidants agents were investigated against cerebral injuries induced by BDL in male rats. METHODS: The animals were distributed into the following groups: Sham, BDL + Vehicle and BDL+ N + M. Neuronal damages were evaluated using biochemical, motor behavioral tasks and morphological assessments. RESULTS: Based on the data, BDL resulted in decreasing locomotor activity, which was reversed by N and M. Morphological study confirmed that BDL led to neurodegeneration in the cortex of the rats, and the N and M treatment preserved cortical neurons. In addition, immunohistochemical (IHC) study of the rat cortex showed that BDL resulted in increasing the activated astrocytes, and the N and M treatment reduced the number of activated cells. CONCLUSION: These results obviously depicted combinational therapy with N and M to exert positive effects in the BDL rats, probably due to their synergistic anti-inflammatory and antioxidant activities.

Choline chloride modulates learning, memory, and synaptic plasticity impairments in maternally separated adolescent male rats.

Maternal separation (MS) is a model to induce permanent alternations in the central nervous system (CNS) and is associated with increased levels of anxiety and cognitive deficiencies. Since methyl donor choline (Ch) has been shown to play a significant role in learning and memory and enhance synaptic plasticity, the authors hypothesized that Ch may attenuate MS-induced impairments in synaptic plasticity and cognitive performance. Rat pups underwent an MS protocol for 180 min/day from postnatal day (PND) 1 to 21. Ch was administered subcutaneously (100 mg/kg, 21 days) to the choline chloride and MS + choline chloride groups from PND 29 to 49. Anxiety-like behaviour, recognition memory, and spatial and passive avoidance learning and memory were measured in the adolescent rats. In addition, evoked field excitatory postsynaptic potentials (fEPSP) were recorded from the CA1 region of the hippocampus. MS induced higher anxiety-like behaviour in the animals. It also impaired learning and memory. However, MS had no effect on locomotor activity. Subcutaneous administration of Ch attenuated MS-induced cognitive deficits and enhanced the learning and memory of MS rats. Ch also decreased anxiety-like behaviour in the open-field test. The present results showed that long-term potentiation (LTP) was induced in all groups except MS and MS + saline animals. However, Ch injection induced LTP and had maintenance in MS + choline chloride, but it was not statistically significant compared with the MS group. In summary, the present findings indicate that MS can interfere with normal animal's cognition and subcutaneous of Ch may be considered an appropriate therapeutic strategy for promoting cognitive dysfunctions in MS animals.

Minocycline Mitigation of Tremor Syndrome and Defect of Cognitive and Balance Induced by Harmaline.

INTRODUCTION: Minocycline has anti-inflammatory, anti-apoptotic, and anti-oxidant effects. Preclinical data suggest that minocycline could be beneficial for treating common neurological disorders, including Parkinson disease and multiple sclerosis. METHODS: In this study, the effects of minocycline on harmaline-induced motor and cognitive impairments were studied in male Wistar rats. The rats were divided into four groups of ten animals each. Harmaline was used for the induction of Essential Tremor (ET). Minocycline (90 mg/kg, IP) was administered 30 minutes before the saline or harmaline. Tremor intensity, spontaneous locomotor activity, passive avoidance memory, anxiety-related behaviors, and motor function were assessed in the rats. RESULTS: The results showed that minocycline could recover tremor intensity and step width but failed to recuperate the motor balance. The memory impairments observed in harmaline-treated rats were somewhat reversed by administration of minocycline. The cerebellum and inferior olive nucleus were studied for neuronal degeneration using histochemistry and transmission electron microscopy techniques. Harmaline caused ultrastructural changes and neuronal cell loss in inferior olive and cerebellar Purkinje cells. Minocycline exhibited neuroprotective changes on cerebellar Purkinje cells and inferior olivary neurons. CONCLUSION: These results open new therapeutic perspectives for motor and memory impairments in ET. However, further studies are needed to clarify the exact mechanisms.

Inhibition of protease-activated receptor 1 (PAR1) ameliorates cognitive performance and synaptic plasticity impairments in animal model of Alzheimer's diseases.

INTRODUCTION: Alzheimer's disease (AD) is a progressive brain disorder accompanied with synaptic failures and decline in cognitive and learning processes. Protease-activated receptor 1 (PAR1) is the major thrombin receptor in the brain that is implicated in synaptic plasticity and memory formation. In the current study, we hypothesized that inhibition of PAR1 would theoretically prevent amyloid beta (Aß) accumulation in the brain and then contribute to reduce risk of AD. The aim of the present study was to evaluate the effect of PAR1 inhibition by using SCH (as an inhibitor of PAR1) on spatial learning, memory, and synaptic plasticity in the CA1 region of the hippocampus in rat model of Alzheimer's disease. METHODS: For the induction of Alzheimer's disease, amyloid beta (Aß) 1-42 was injected in the CA1 region of the hippocampus. The rats were divided into four groups: group I (surgical sham); group II rat mode of Alzheimer's disease (AD); group III (SCH) (25 µg/kg) intraperitoneally (i.p.), and group IV (AD + SCH). After 14 days of protocol, the rats in group III received SCH and 30 min after injection behavioral and electrophysiological tests were performed. Learning and memory ability was assessed by Morris water maze and novel object recognition tests. Extracellular evoked field excitatory postsynaptic potentials (fEPSP) were recorded in the stratum radiatum of the CA1 area. RESULTS: Our results showed that AD rats showed impairments in learning and memory, and long-term potentiation (LTP) was not induced in these rats. However, injection of SCH overcame the AD-induced impairment in LTP generation in the CA1 area of the hippocampus and improved learning and memory impairment.