Impairment In Male Rats Research Articles

Memory enhancement by administration of ginger (Zingiber officinale) extract on morphine-induced memory impairment in male rats

To study the chronic treatment with hydroethanolic extract of ginger (50, 100 and 200 mg/kg, p.o) would effect on the passive avoidance learning (PAL) and memory in rat. MethodsThe rats were divided into eight groups. On the training trial, the mice received an electric shock when the animals were entered into the dark compartment. Twenty-four hours later, 30 min after treatment, the STL (step-through latency) and TDC (total time in dark compartments) was recorded and defined as the retention trial. ResultsThe time latency in morphine-treated group was lower than control (P<0.001). Treatment of the animals by 100 and 200 mg/kg of ginger extract before the training trial increased the time latency at 24 hours after the training trial (P<0.01 and P<0.001). Administration of both 100 and 200 mg/kg doses of the extract in morphine received animal groups before retention trials also increased the time latency than the morphine-treated group groups (P<0.001). ConclusionThe results revealed that the ginger extract attenuated morphine-induced memory impairment.

Nitric oxide mediates the beneficial effect of chronic naltrexone on cholestasis-induced memory impairment in male rats

Recent studies suggest an augmentation of endogenous opioids following bile duct ligation (BDL) and their pivotal role in the pathophysiology of cholestasis. In this study, the effect of naltrexone, an opioid receptor antagonist, was determined on cholestasis-induced memory impairment and the possible involvement of nitric oxide (NO) in this effect. Male Albino-Wistar rats were randomized to sham-operated and BDL-operated groups. In each group, animals were treated for up to 28 days with saline; naltrexone (10 mg/kg); naltrexone and N(G)-nitro-L-arginine methyl ester (L-NAME), a nonselective nitric oxide synthase (NOS) inhibitor (3, 10 mg/kg); naltrexone and aminoguanidine, an inducible NOS inhibitor (100 mg/kg); or methylnaltrexone, a peripherally acting opioid receptor antagonist (3 mg/kg, intraperitoneal). Spatial recognition memory was determined in a Y-maze task on the day before surgery and days 7, 14, 21, and 28 after surgery. Memory performance was impaired 14 days after BDL in cholestatic rats and was significantly reversed by chronic treatment with naltrexone at days 14, 21, and 28 after BDL. On day 21 after BDL, chronic L-NAME produced only a nonsignificant decrease in the beneficial effect of naltrexone, whereas on day 28, chronic administration of both L-NAME and aminoguanidine significantly reversed this effect of naltrexone. It is therefore shown in this study that naltrexone improves BDL-induced memory deficit in rats. We conclude that the memory impairment in cholestatic rats might be because of an increase in the level of endogenous opioids and that naltrexone improved the spatial recognition memory by antagonizing opioid receptors. The observation that the procognitive effect of naltrexone is counteracted either by general inhibition of NOS enzymes or by selective inhibition of inducible NOS suggests the nitrergic pathway as a probable mechanism involved in the amelioration of spatial recognition memory by naltrexone in BDL rats.

Sex differences in adult cognitive deficits after adolescent nicotine exposure in rats

This study was designed to determine whether deficits in adult serial pattern learning caused by adolescent nicotine exposure persist as impairments in asymptotic performance, whether adolescent nicotine exposure differentially retards learning about pattern elements that are inconsistent with “perfect” pattern structure, and whether there are sex differences in rats' response to adolescent nicotine exposure as assessed by a serial multiple choice task. The current study replicated the results of our initial report (Fountain et al., 2008) using this task by showing that adolescent nicotine exposure (1.0mg/kg/day nicotine for 35days) produced a specific cognitive impairment in male rats that persisted into adulthood at least a month after adolescent nicotine exposure ended. In addition, sex differences were observed even in controls, with additional evidence that adolescent nicotine exposure significantly impaired learning relative to same-sex controls for chunk boundary elements in males and for violation elements in females. All nicotine-induced impairments were overcome by additional training so that groups did not differ at asymptote. An examination of the types of errors rats made indicated that adolescent nicotine exposure slowed learning without affecting rats' cognitive strategy in the task. This data pattern suggests that exposure to nicotine in adolescence may have impaired different aspects of adult stimulus–response discrimination learning processes in males and females, but left abstract rule learning processes relatively spared in both sexes. These effects converge with other findings in the field and reinforce the concern that adolescent nicotine exposure poses an important threat to cognitive capacity in adulthood.

Social play impairment following status epilepticus during early development

Neonatal status epilepticus (SE) disrupts prefrontal cortex and thalamus, brain regions related to social play. Juvenile play was evaluated using the "intruder-resident" paradigm following SE in 9-day-old Wistar pups of both genders. Quite interestingly, we demonstrated for the first time that neonatal SE produces social impairment in male rats, reduces locomotor activity in both genders and enhances self-grooming in female. Additional studies are necessary to clarify if these effects can impair social behavior across the life span.

The Effect of Aqueous Crocus sativus L. Extract on Intracerebroventricular Streptozotocin-induced Cognitive Deficits in Rat: a Behavioral Analysis

Intracerebroventricular (ICV) injection of streptozotocin (STZ) causes cognitive impairment in rats. The beneficial effect of Crocus sativus L. extract (CSE) was evaluated on ICV STZ-induced learning, memory, and cognitive impairment in male rats. For this purpose, rats were injected with ICV STZ bilaterally, on days 1 and 3 (3 mg/kg). The STZ-injected rats received CSE (60 mg/kg; i.p.) every other day, starting one day before surgery, for three weeks. The learning and memory performance was assessed using passive avoidance paradigm, and for spatial cognition evaluation, Y-maze task was used. It was found that CSE-treated STZinjected rats show higher correct choices and lower errors in Y maze than vehicle-treated STZinjected rats. In addition, CSE administration significantly attenuated learning and memory impairment in treated STZ-injected group in passive avoidance test. Therefore, these results demonstrate the effectiveness of CSE in preventing the cognitive deficits caused by ICV STZ in rats and its potential in the treatment of neurodegenerative diseases such as Alzheimer’s disease (AD).

Late-emerging cognitive impairment in male rats after neonatal parathion exposure

Late-emerging cognitive impairment in male rats after neonatal parathion exposure

Effect of Naringenin on Intracerebroventricular Streptozotocin-Induced Cognitive Deficits in Rat: A Behavioral Analysis

Intracerebroventricular (ICV) injection of streptozotocin (STZ) causes cognitive impairment in rats. The beneficial effect of naringenin (NAR) was investigated on ICV STZ-induced learning, memory, and cognitive impairment in male rats. For this purpose, rats were injected with ICV STZ bilaterally, on days 1 and 3 (3 mg/kg). The STZ-injected rats received NAR (50 mg/kg/day p.o.) starting 1 day pre-surgery for 3 weeks. The learning and memory performance was assessed using passive avoidance paradigm, and for spatial cognition evaluation, radial eight-arm maze (RAM) task was used. It was found out that NAR-treated STZ-injected rats show higher correct choices and lower errors in RAM than vehicle-treated STZ-injected rats. In addition, NAR administration significantly attenuated learning and memory impairment in treated STZ-injected group in passive avoidance test. Therefore, these results demonstrate the effectiveness of NAR in preventing the cognitive deficits caused by ICV STZ in rats and its potential in the treatment of neurodegenerative diseases such as Alzheimer’s disease.

Tissue Distribution and Excretion of N-Methyl-2-Pyrrolidone in Male and Female Rats

N-methyl-2-pyrrolidone (NMP) belongs to solvents widely used in the petrochemical industry a well as in the production of pesticides, veterinary drugs and paint removers. NMP is easily absorbed from the respiratory tract, digestive system and through the skin. It is a compound of slight acute toxicity that also displays moderate irritating activity. The aim of this study was to assess tissue distribution and excretion following a single intraperitoneal NMP administration. Tissue distribution and excretion of NMP following administration of a single dose of 250 mg/kg body weight (350 kBq/rat) was investigated using 14C. Blood plasma (6 rats per time point) were sampled up to 72 h after administration and determination of radioactivity. Male and female rats (4 animals per time point) were decapitated at appropriate time intervals and examined tissues were removed for determination of radioactivity. Excretion of 14C in urine and feces were also measured. All radioactivity measurements were carried out using a Rackbetta 1209 (LKB, Sweden) liquid scintillation counter. The highest 14C activity in tissues and internal organs of female and male rats was observed 4 h after administration of the compound. The highest accumulation was detected in the muscles and fat tissue as well as in the liver and testicles. During 72 h following administration, approximately 80% of the dose was excreted in urine. Elimination of the compound in feces was far less significant: only about 5% of the dose was excreted at once. The results of the study indicate that there are no significant differences in 14C-NMP tissue distribution between male and female rats; NMP absorption from the peritoneal cavity to blood is rapid, disappearance from plasma is monophase and kidneys are the main route of excretion of NMP and/or its metabolites from the rat body after administration of a dose equal to 10% of LD50. The ability to accumulate NMP and/or its metabolites in testes and seminal vesicles may be the reason for fertility impairment in male rats observed after repeated exposure to this compound.

Effect of hexacosanol on the characteristics of novel sustained-release allopurinol solid lipospheres (SLS): factorial design application and product evaluation

This investigation involved the evaluation of the effect of hexacosanol (HC, ceryl alcohol), a new hydrophobic wax modifier (WM) in comparison with conventional modifiers, on the development of sustained-release allopurinol (AP) solid lipospheres (SLS) intended for use in a suspension formulation and other oral dosage forms. Various beeswax (BW)/WM blends (composition ratio 1:1) were thus used to prepare SLS by a modified oil-in-water emulsion meltable disperse-phase (MDP) encapsulation method without using organic solvents and the influence of these blends on the drug encapsulation efficiency (EE), size distribution and the time for 50% of the drug to be released ( t 50%) was investigated. Results indicated that incorporation of HC in wall matrix of SLS provided the means to enhance the EE of AP and to modulate the rate of drug release into dissolution media (simulated gastric fluid (S.G.F.: pH 1.2) and simulated intestinal fluid (S.I.F.: pH 7.4). The effects of the process variables; HC concentration, dispersant (pluronic F-68: PF-68) concentration and drug:wax ratio were also studied on the properties of AP-loaded SLS by a 2 3 factorial design. The EE values were in the range of 80.8–92.67%. The only significant parameter affecting ( P < 0.01) the size and size distribution of the SLS formulations was the amount of the PF-68, whereas the factor with the biggest influence ( P < 0.05) on the drug EE was the initial loading of AP (in terms of the drug:wax ratio). The amount of HC blended with wax and the initial drug loading significantly ( P < 0.01) affected the t 50% values of all of the formulations. The release of AP was more extended ( t 50% values (S.I.F.; pH 7.4) = 9.91–25.36 h, depending on the drug:wax ratio) and surface morphology of SLS was improved with higher HC content (15%, w/w) formulations. The release patterns fitted the Baker–Lonsdale dissolution kinetics for spherical matrices. A significant decrease of plasma uric acid levels ( P < 0.05) and hepatic impairment in male rats was observed after oral administration of a SLS (mean size: 120 μm) suspensions of the optimum formulation, compared to suspensions of pure AP.