Method for the identification of pharmacological intervention for the disruption of fear memory in PTSD-rat model.

A large portion of the human population is exposed to traumatic events once in their lifetime, 10% of which may undergo post-traumatic stress disorder (PTSD). It is a mental condition triggered by a traumatic event resulting in severe anxiety disorder which may severely affect the daily routine life of the individual. The patient expresses the aversive memory by recalling any fear event related to the traumatic experience. The disruption of fear memory related to fear event is one of the best approaches to treat PTSD. In this regard, pharmacological interventions provide a possible way to erase or lessen the fear memory of the traumatic event. The screening and identification of drugs is one of the crucial steps to introduce new potent drugs in preclinical setup. Pavlovian fear conditioning is the well known experimental protocol to study fear memory. In this article, we are presenting a detailed method of Pavlovian fear conditioning which we have optimized in our lab for the identification of drugs having the potential to disrupt fear memory in the PTSD-rat model. In this protocol, various stages of memory formation including consolidation, reconsolidation, and extinction have been targeted to study the effect of a particular drug.•The protocol provides step by step procedure to study the effects of known or putative drugs in an animal model of PTSD.•The method also explains the separate protocols to target specific stages of memory so that one can identify the effects of drugs on a particular phase of remote or recent memory formation.

Blockade of muscarinic receptors impairs reconsolidation of older fear memory by decreasing cholinergic neurotransmission: A study in rat model of PTSD.

The age and strength of fear memory are two potential parameters that can be influenced by the impairing effects of pharmacological agents on reconsolidation of fear memory. In reconsolidation, stored information is rendered labile again after being reactivated. Pharmacological manipulations at this stage result in an inability to retrieve the fear memories, suggesting that they are erased or persistently inhibited. This fear memory impairment phenomenon can be valuable to treat post-traumatic stress disorders (PTSD). Previously ß-adrenergic antagonist propranolol has been repeatedly reported to impair fear memory in the treatment of PTSD. Atropine has also shown to disrupt memory formation. The present study was therefore designed to compare the effects of atropine and propranolol on reconsolidation of older fear memory in rat model of PTSD using Pavlovian fear conditioning apparatus. For this purpose 18 rats were taken and divided into control, atropine and propranolol groups and subjected to Pavlovian fear conditioning trials in order to develop animal model of PTSD. To evaluate the reconsolidation impairment of fear memory by atropine and propranolol, short term and long term memory was tested after reactivation of fear memory in rats. The present findings demonstrate that atropine significantly decreases fear expression. These results suggest that atropine significantly reduces the strength of fear memories and may be effective in the treatment of psychiatric disorders especially in PTSD.

Naringenin protects AlCl3/D-galactose induced neurotoxicity in rat model of AD via attenuation of acetylcholinesterase levels and inhibition of oxidative stress.

Currently prescribed medications for the treatment of Alzheimer's disease (AD) that are based on acetylcholinesterase inhibition only offer symptomatic relief but do not provide protection against neurodegeneration. There appear to be an intense need for the development of therapeutic strategies that not only improve brain functions but also prevent neurodegeneration. The oxidative stress is one of the main causative factors of AD. Various antioxidants are being investigated to prevent neurodegeneration in AD. The objective of this study was to investigate the neuroprotective effects of naringenin (NAR) against AlCl3+D-gal induced AD-like symptoms in an animal model. Rats were orally pre-treated with NAR (50 mg/kg) for two weeks and then exposed to AlCl3+D-gal (150 mg/kg + 300 mg/kg) intraperitoneally for one week to develop AD-like symptoms. The standard drug, donepezil (DPZ) was used as a stimulator of cholinergic activity. Our results showed that NAR pre-treatment significantly protected AD-like behavioral disturbances in rats. In DPZ group, rats showed improved cognitive and cholinergic functions but the neuropsychiatric functions were not completely improved and showed marked histopathological alterations. However, NAR not only prevented AlCl3+D-gal induced AD-like symptoms but also significantly prevented neuropsychiatric dysfunctions in rats. Results of present study suggest that NAR may play a role in enhancing neuroprotective and cognition functions and it can potentially be considered as a neuroprotective compound for therapeutic management of AD in the future.

Quantitative and qualitative assessment of additives present in broiler chicken feed and meat and their implications for human health.

OBJECTIVE: To determine the various constituents of commercial, broiler chicken feed and the presence of these constituents in their meat. METHODS: The experimental study was conducted at the Pakistan Council of Scientific and Industrial Research laboratory, Karachi. Samples of commercial broiler chicken feed and meat were collected in 2015 from a large poultry farm that supplies chicken meat to various suburban areas of the city. Another set of organic chickens were bred in an animal house. The samples of feed, meat and droppings were then analysed for the estimation of basic constituents and additives in the laboratory. Data was analysed using SPSS 20.0. RESULTS: The constituents were measured in 26 samples of chicken meat from each group. Calories (p<0.01), amount of protein (p<0.01), total fats (p<0.05), cholesterol (p<0.01), saturated fats (p<0.01), monounsaturated (p<0.05) and polyunsaturated fats (p<0.01) were significantly increased in commercial broiler chicken compared to that of organic chicken meat. The commercial chicken feed was found to contain crude carbohydrate, crude protein, crude fat, crude fibre, vitamins, amino acids, premixes of vitamins and toxicities of roxarsone, melamine and pesticides. Additive constituents were also present in the commercial chicken meat. These components were absent in organic chicken meat and droppings which suggests that they were absent in their feeding contents. CONCLUSIONS: Organic chickens were found to be safer for consumption than commercial chickens.

Physical enrichment enhances memory function by regulating stress hormone and brain acetylcholinesterase activity in rats exposed to restraint stress.

To study the effects of stress on mental health activity is of great importance in neuropsychological studies as it may affect the lifelong performance related to brain and overall health and wellbeing of an individual. It is observed very often that exposure to stress during early life can alter the brain function which may reflect as cognitive disability. Impairment of memory is associated with increased oxidative stress which is due to enhanced production of free radicals that may lead to lipid peroxidation and disintegration of cell structure and functions. Exposure to enriched environment has shown to enhance spatial learning and memory, although the underlying mechanism covering the regulation of antioxidant capacity is limited. Here we investigated short and long term memory using Morris water maze before and after giving restraint stress procedure in rats exposed to social and physically enriched environment. Levels of malondialdehyde (MDA), activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and acetylcholinesterase (AChE) in brain tissue were estimated. Plasma corticosterone was also determined after decapitation. Results demonstrated that rats pre-exposed to physical along with social enrichment showed improved short and long term memory as compared to control group. However, restraint stress exerted differential effects in socially and physically enriched groups. Reduced lipid peroxidation and decreased activity of SOD, GPx and AChE were observed in physically enriched rats subjected to stress as compared to stressed rats kept in social environment. Levels of corticosterone were also found to be significantly reduced in rats kept in physically enriched environment. This study shows the beneficial effects of environmental enrichment on learning and spatial memory by reducing oxidative stress via reducing lipid peroxidation and regulation of antioxidant enzymes in rats.

Anticholinergic drug atropine diminishes newly formed fear memory in male rats.

Post-traumatic stress disorder (PTSD) is a condition which is triggered shortly after experiencing traumatic events. PTSD is complicated by the fact that people with PTSD often develop additional disorders such as phobias, addiction, depression, panic disorder and obsessive-compulsive disorder. Beta-adrenergic and cholinergic system both are involved in memory formation as well as in emotional response associated with memory. It is reported that the administration of beta-adrenergic and cholinergic antagonist results in the impairment in memory formation. Here, we examined the potential of beta-adrenergic antagonist propranolol and muscarinic cholinergic antagonist atropine for impairing the recently formed fear memory associated with PTSD. Reconsolidation is the memory process during which labile memory converts into permanent memory. In this study it is hypothesized that if recently formed fear memory is disturbed during reconsolidation phase by pharmacological intervention then it could be possible to impair well-consolidated fear memory. Atropine and propranolol were injected in separate set of rats (n=6) just after the reactivation of fear memory. Short term memory and long term memory were monitored after 2 h and 24 h of reactivation respectively. Results of current study demonstrated that only atropine showed significant impairment of reconsolidation of newly formed fear memory whereas propranolol did not show fear memory disrupting effects. The results emphasize the significance of pharmacological intervention to impair reconsolidation of newly formed fear memory.

Naringenin-induced enhanced antioxidant defence system meliorates cholinergic neurotransmission and consolidates memory in male rats.

AIMS: Free radical mediated neurotoxicity is a leading cause of neurodegenerative disorders. Neurodegeneration due to oxidative stress can produce cognitive dysfunctions. Flavonoids and curcuminoids are naturally occurring polyphenolic compounds that display a variety of therapeutic importance against oxidative stress. MAIN METHODS: This study was designed to assess potential role of polyphenolic compounds in neurocognitive functions and prevention against oxidative stress. For this purpose, young rats were orally treated with naringenin (NAR), curcumin (CUR) and quercetin (QUE) at a dose of 50mg/kg, 200mg/kg and 50mg/kg respectively for 16days. At 4th day of drug administration cognitive functions were monitored by Morris water maze (MWM) test. In MWM cognitive functions in terms of learning acquisition (1h after training), retention (24h after training), memory extinction (4days after training), and reconsolidation (8 and 12days after training) were monitored. Biochemical and neurochemical analysis were done in whole brain. KEY FINDINGS: Treatment of NAR, CUR and QUE significantly enhanced learning acquisition, memory retention and reconsolidation and prevented memory extinction. Treatment of NAR and QUE prevented the alteration of brain antioxidant defence system by enhancing antioxidant enzyme activities and increasing antioxidant compound concentration. Oxidative stress in terms of lipid peroxidation was significantly prevented in treated rats. Serotonergic and cholinergic improvement was also found in treated rats. SIGNIFICANCE: The present study therefore provides biological evidence supporting the usefulness of these polyphenolic compounds in daily life for improvement of cognitive abilities and hence may have a potential role in the management of dementia and related disorders.

Dizocilpine induced psychosis-like behavior in rats: A possible animal model with full spectrum of schizophrenia.

Schizophrenia (SZ) is categorized as neuropsychiatric disorder with reduced lifespan and significant impairments in social and vocational functioning. One of the best proposed pharmacological animal models is dizocilpine, as it can mimic the full spectrum of schizophrenic disorder including positive and negative symptoms along with cognitive deficits. Dizocilpine is N-methyl-D-aspartate (NMDA) receptor antagonist known to induce hyper-locomotion and stereotyped behavior in rodents. Present study was designed to develop an animal model of SZ via intraperitoneal administration of dizocilpine in rats (100-150g) at a dose of 0.3 mg/kg for eight days. For the evaluation of positive symptoms, hyperlocomotor behavior was monitored. Negative symptoms were assessed by sucrose preference test (SPT) and social interaction test (SIT). Moreover, Cognitive deficits were evaluated by novel object recognition test (NORT). After behavioral assessments animals were decapitated for further evaluation of biochemical and neurochemical estimations. Present findings revealed that dizocilpine injected rats exhibited significant hyperlocomotor behavior, depressive symptoms and cognitive deficits. Results are further strengthened with a marked increase in lipid per oxidation (LPO) in brain and a decline in reduced glutathione (GSH) levels. Biogenic amine levels (Dopamine, DA; 5-hydroxytryptamine, 5-HT) were also significantly increased and decreased respectively. Thus, present findings suggest that dizocilpine can be used as one of the best drug to develop psychosis-like symptoms in rats and to develop an animal model following a short-term study.

The role of genomic islands in Escherichia coli K1 interactions with intestinal and kidney epithelial cells.

The completion of Escherichia coli K1 genome has identified several genomic islands that are present in meningitis-causing E. coli RS218 but absent in the non-pathogenic E. coli MG1655. In this study, the role of various genomic islands in E. coli K1 interactions with intestinal epithelial cells (Caco-2) and kidney epithelial cells (MA104) was determined. Using association assays, invasion assays, and intracellular survival assays, the findings revealed that the genomic island deletion mutants of RS218 related to P fimbriae, S fimbriae, F17-like fimbriae, non-fimbrial adhesins, Hek and hemagglutinin, protein secretion system (T1SS for hemolysin; T2SS; T5SS for antigen 43), Iro system and hmu system), invasins (CNF1, IbeA), toxins (α-hemolysin), K1 capsule biosynthesis, metabolism (d-serine catabolism, dihydroxyacetone, glycerol, and glyoxylate metabolism), prophage genes, showed reduced interactions with both cell types. Next, we determined the role of various genomic islands in E. coli K1 resistance to serum. When exposed to the normal human serum, the viability of the genomic island deletion mutants related to adhesins such as S fimbriae, P fimbriae, F17-like fimbriae, non-fimbrial adhesins, Hek and hemagglutinin, antigen 43 and T5SS for antigen 43, T2SS, and T1SS for hemolysin, Iro system and hmu system, prophage genes, metabolism (sugar metabolism and d-serine catabolism), K1 capsule biosynthesis, and invasins such as CNF1 was affected, suggesting their role in bacteremia. The characterization of these genomic islands should reveal mechanisms of E. coli K1 pathogenicity that could be of value as therapeutic targets.

Repeated administration of almonds increases brain acetylcholine levels and enhances memory function in healthy rats while attenuates memory deficits in animal model of amnesia.

Dietary nutrients may play a vital role in protecting the brain from age-related memory dysfunction and neurodegenerative diseases. Tree nuts including almonds have shown potential to combat age-associated brain dysfunction. These nuts are an important source of essential nutrients, such as tocopherol, folate, mono- and poly-unsaturated fatty acids, and polyphenols. These components have shown promise as possible dietary supplements to prevent or delay the onset of age-associated cognitive dysfunction. This study investigated possible protective potential of almond against scopolamine induced amnesia in rats. The present study also investigated a role of acetylcholine in almond induced memory enhancement. Rats in test group were orally administrated with almond suspension (400 mg/kg/day) for four weeks. Both control and almond-treated rats were then divided into saline and scopolamine injected groups. Rats in the scopolamine group were injected with scopolamine (0.5 mg/kg) five minutes before the start of each memory test. Memory was assessed by elevated plus maze (EPM), Morris water maze (MWM) and novel object recognition (NOR) task. Cholinergic function was determined in terms of hippocampal and frontal cortical acetylcholine content and acetylcholinesterase activity. Results of the present study suggest that almond administration for 28 days significantly improved memory retention. This memory enhancing effect of almond was also observed in scopolamine induced amnesia model. Present study also suggests a role of acetylcholine in the attenuation of scopolamine induced amnesia by almond.