ABSTRACT
In the present study, we have monitored dose dependent effects of apomorphine on learning and memory. Behavioral sensitization and craving, which develop upon repeated treatment with dopamine receptor agonist apomorphine, are major limitations of the therapeutic use of apomorphine in Parkinson's patients. Effects of single [intraperitoneal] injection of apomorphine at different doses [i.e., 0.5, 1.0, and 2.0 mg/ml/kg] on locomotion in a familiar environment [Skinner's box] and memory in Morris water maze were investigated. Results show significantly enhanced activity in Skinner's box in a dose dependant manner. Low dose [0.5 mg/ml/kg] of apomorphine impaired both short- as well as long-term memory while both high and moderate doses of the drug [1.0, and 2.0 mg/ml/kg] enhanced the cognitive profile in rats. However, the memory-enhancing effects of apomorphine at moderate [1.0 mg/ml/kg] dose were more pronounced as compared to high [2.0 mg/ml/kg] dose of the drug. Rats were decapitated on day 2. Whole brains of rats were collected and stored at -70 degree C. Biogenic amines [i.e., 5-Hydroxytryptamine; 5-HT and dopamine] and metabolites [i.e., Dihydroxyphenylacetic acid; DOPAC, Homovanillic acid; HVA and 5-Hydroxyindoleacetic acid; 5HIAA] were estimated by reverse phase High Performance Liquid Chromatography with electrochemical detector [HPLC-EC]. Both low [0.5mg/ml/kg] as well as moderate [1.0mg/ml/kg] dose of apomorphine increased levels of dopamine, DOPAC, HVA, 5-HT and 5-HIAA. Whereas, high [4.0 mg/kg] dose of apomorphine increased levels of dopamine, DOPAC and HVA, while decreased 5-HT and 5-HIAA levels. Results would be helpful in elucidating memory enhancing effects of apomorphine at different doses and its implication for extending therapeutics in cognitive disorders
ABSTRACT
Diet has a great impact on brain health and function. It plays an important role to improve and control a number of psychiatric disorders such as depression, anxiety, hyperactivity and behavioral impulsivity. Anorexia Nervosa [AN] is one of the psychiatric disorder which is associated with diet. In AN, patients show extreme dieting, weight loss, hyperactivity, depression/anxiety, self-control and behavioral impulsivity. Previous studies showed that during diet restriction, tryptophan decreases serotonin [5-hydroxytryptamine; 5-HT] metabolism in the brain due to its less availability and contributes psychiatric problems associated with AN. The present study is designed to investigate the effects of tryptophan administration on 5-HT metabolism in diet-restricted rats. Tryptophan at a dose of 50 or 100mg/kg was given orally to respective freely fed [FF] or diet restricted [DR] animals daily for five weeks. Behavioral activities were also monitored weekly. The results show significant effect [p<0.05] on behavior in activity box, open field and in light/dark transition test by tryptophan administration in diet-restricted rats. This may be associated with the increased in serum tryptophan and brain 5-HT metabolism. Therefore, it is concluded that diet-restriction-induced behavioral changes might be reverted back with the administration of tryptophan and may be helpful to improve psychological problems in AN
ABSTRACT
The concentration of 5-hydroxytryptamine [5-HT, Serotonin] varies as a result of physiological changes in the availability of its precursor tryptophan to the serotonergic neurons in the brain. Increase in brain tryptophan occurs following an increase in plasma tryptophan concentration. Tryptophan intake increases brain serotonin metabolism and enhances memory. The Present study was designed to investigate the effects of oral administration of tryptophan [TRP] at different doses [100, 300 and 500mg/kg] for two weeks on learning and memory functions and Neurochemical changes in rats. Control rats were given drinking water. Assessment of memory in rats was done by using the water Maze, on the 14th day trail training of water Maze was given to rats and after Ih of this 2[nd] trial of these rats were done. On the next day [After 24h of trail] long-term memories of these rats were monitored. After 1 hour of this all rats were killed by decapitation using guillotine. Brain and blood was collected and stored at -70°C. Neurochemical estimations of Plasma and brain tryptophan, 5-HT and 5-HIAA in brain were made by HPLC-EC. Result showed that administration of tryptophan enhanced performance on water Maze test. Tryptophan treated animals exhibited higher level of Plasma as well as brain tryptophan. 5-HT and 5-HIAA levels were also increased in tryptophan treated rats. Findings are discussed in context with the role of 5-HT metabolism in learning and memory process in rats. Results may help to understand the 5-HT changes following long term TRP administration in a dose dependent manner and will help to suggest the use of TRP in serotonin related illnesses
ABSTRACT
Effects of administration of imipramine [IMI] are determined on haloperidoJ-induced extrapyramidal vmptoms [EPS]
Haloperidol is administered orally at a dose of 0.2 mg/rat/day in rats for a period of 5 weeks, by this catment rats developed vacuous chewing movements [VCMs] after 2 weeks, which increased in a time dependent iiianner as the treatment continued for 5 weeks. Motor coordination [assess on rota rod activity] impaired maximally after 3 weeks and tolerance was developed in the haloperidol induced motor impairment after 5 weeks of treatment. Motor activity in an open field or activity box was not altered
The administration of IMI [intraperitoneally, for 5 weeks] did not affect motor activity or motor coordination
Co-administration of IMI at a dose of 5 mg/ml/kg/day attenuated the induction of haloperidol elicited VCMs [Quantitative orofacial dyskinesia] as well impairment of motor coordination. Results are discussed in the context of the mechanism involved by which imipramine attenuated haloperidol-induced EPS
ABSTRACT
The present study was designed to monitor extrapyramidal symptoms [EPS] elicited by the oral administration of haloperidol at clinically recommended doses and to compare it with EPS produced when the drug is injected intraperitoneally at doses used in animal research. Rats injected with haloperidol at a dose of 1 mg/kg daily for 5 weeks exhibited akinesia in an open field and impaired motor coordination. Effects of the drug on motor coordination but not on open field akinesia were attenuated gradually from 2-5 weeks of treatment. Oral administration of haloperidol in drinking water at clinically recommended dose exhibited decreased exploratory activity without producing akinesia. Motor coordination was impaired maximally after 3 weeks and tolerance was developed in the drug induced motor impairment after 5 weeks of treatment. Intensity of vacuous chewing movements [VCMs] and tardive VCMs was greater by oral administration than intraperitoneal injections of haloperidol. The present results showed that oral administration of haloperidol expected to produce sustained effect may result in tolerance in acute parkinsonian like effects but more intensity of tardive dyskinesia. We suggest that drugs which may helpful in alleviating tardive dyskinesia may be more useful if person is on oral drug therapy
ABSTRACT
Background: Examination stress is a psychological stress that activate hypothalamic-pituitary adrenocortical [HPA] axis to increase circulating levels of glucocorticoids. The fat derived hormone leptin is also released in response to stress-inducing condition. To workout the role of leptin and cortisol in response to perceived levels of examination stress and their effects on academic performance. The present study was designed to monitor the relationship of self reported perceived levels of examination stress on serum levels of cortisol and leptin in female students going to appear in university examination. Methods: Fifty-six female undergraduate students participated in the study. Examination stress, appetite levels were assessed by a questionnaire and blood samples were collected one hour before appearing in the examination. Performance was evaluated from the marks obtained in that particular examination. Results: Serum cortisol levels increased with an increase in the intensity of perceived examination stress. Serum leptin levels increased only in the group under moderate stress while increases in mild and severe stress group were not significant. Mild to moderate stress enhanced performance but severe stress decreased it. Conclusions: The present study shows an inverted U-shaped relationship between self reported different levels of perceived examination stress and academic performance. Keywords: Academic Stress, Cortisol, Leptin, Appetite, Performance
ABSTRACT
Aim of this study was to determine the effect of diazepam on serum electrolytes [sodium, potassium, calcium, and magnesium], osmolarity and anxiolysis of 2hrs restraint stressed rats. Male Albino Wistar rats were used in experiment. Test animals were injected diazepam intrap-eritoneal and control deionized water. After thirty minutes of injection control and test animals were further divided into restrained and unrestrained groups. Animals of unrestrained group were kept in home cages, while restrained grouped animals were restrained by immobilizing for two hours [2hrs] on wire grids. Next day light-dark box activity was monitored for 5 minutes. Rats were decapitated. Blood was collected and serum separated for analysis of electrolytes. Results showed that diazepam increases the serum sodium, potassium, calcium, concentration significantly [p<0.01]. It also increases the osmolarity; number of events and time spent in light box but decreased magnesium concentration significantly [P<0.01] in stressed and unstressed rats. It is concluded that the diazepam reverse the stressed produced changes in serum electrolytes and plasma osmolarity
ABSTRACT
Aim of this study was to determine the effect of immobilization stress on serum electrolytes [sodium, potassium, calcium and magnesium] in rats. Male albino wistar rats were used in experiment. Test animals were restrained by immobilizing for two hours on wire grids. Control animals were kept unrestrained in home cages. Rats were killed after the termination of restraint period. Blood was collected and serum separated for the analysis of electrolytes. Serum sodium, potassium and calcium were analyzed by flame photometer. Magnesium content was determined by spectrophotometer. Result shows a significant decreased [P = 0.001] in sodium, potassium, and calcium but increased [P = 0.001] in magnesium serum level. It is concluded that stress induced decrease in sodium, potassium and calcium and increase in serum magnesium level may contribute to stress induce hypertension