Tahira Parveen

Brain regional serotonin synthesis following adaptation to repeated restraint

A single 2 h episode of restraint stress decreased food intake and growth rate of rats. These deficits were not observed after five restraint periods of 2 h a day, suggesting that adaptation occurred. An acute challenge with 2 h restraint increased 5-hydroxytryptamine (5-HT) synthesis rate in the cortex, hypothalamus, midbrain and hindbrain of previously unrestrained rats, but not those adapted to 5 days of 2 h daily restraint. Hippocampal and striatal 5-HT synthesis was not increased significantly by 2 h restraint in previously unrestrained rats but was increased and decreased, respectively, in rats exposed to five 2 h daily restraints, when they were restrained on the sixth day. The findings suggest an important role of 5-HT particularly in the hippocampus, in adaptation to stress.

Inhibition of restraint-induced anorexia by injected tryptophan

Tryptophan injected at doses of 50mg/kg did not alter 24 h cumulative food intake and growth rate in rats. A single episode of 2 h restraint stress decreased food intake and growth rate of saline and tryptophan injected rats. The decreases of both food intake and growth rate were smaller in tryptophan injected (food intake 23.9% p<0.05; growth rate 2.9% p<0.05) than saline injected (food intake 78.5% p<0.01; growth rate 6.1% p<0.01) rats suggesting that tryptophan administration inhibits restraint-induced anorexia. Following an acute challenge with 2h restraint increases of 5-hydroxytryptamine (5-HT; serotonin) and 5-hydroxyindoleacetic acid (5-HIAA) but not tryptophan were greater in tryptophan injected than saline injected rats. The findings imply that tryptophan-induced increases of brain 5-HT and 5-HIAA have little effect on functional serotoninergic activity under basal conditions but a facilitatory effect on functional response occurs in conditions of increased serotoninergic neuronal activity such as during stress.

Alkaloids from Veratrum album

Abstract Leaves of Veratrum album of Turkish origin have yielded two new steroidal alkaloids, O -acetyljervine and methyljervine- N -3′-propanoate along with the known alkaloid jervine. The structures of these new bases were established on the basis of 2D NMR and other spectroscopic techniques.

Enhancement and inhibition of apomorphine-induced sensitization in rats exposed to immobilization stress: Relationship with adaptation to stress

Stress increases vulnerability to addiction while drugs of abuse impair coping responses and pre-dispose to depression. Pre-clinical research shows that stress exposure augments locomotor sensitization effects of drugs of abuse and impairs behavioral tolerance to repeated stress. The present study investigates relationship between behavioral tolerance to repeated immobilization stress and apomorphine-induced sensitization. Apomorphine was injected either before exposure or after the termination of immobilization, daily for 5 days, to monitor drug-induced behavioral sensitization and tolerance in immobilization stress-induced anorexia. We find that apomorphine-induced sensitization is enhanced and tolerance to repeated immobilization is impaired if the drug is administered before exposure to stress episode. Conversely, apomorphine-induced sensitization is inhibited and adaptation to stress is facilitated if the drug is administered after the termination of stress episode. It shows that apomorphine, if experienced during stress, produces greater sensitization and impairs stress tolerance. Conversely, sensitization effects of apomorphine are blocked and tolerance to stress is facilitated in animals receiving drug after the termination of stress episode. It is suggested that additive effects of stress and apomorphine on mesocorticolimbic dopamine neurotransmission and 5-HT-1A influences on dopamine neurotransmission may have a role in the modulation of apomorphine sensitization and tolerance to repeated immobilization stress. The results may help develop potential pharmacotherapies when substance abuse/dependence disorder and depression occur together.

Attenuation of stress-induced behavioral deficits by lithium administration via serotonin metabolism

BACKGROUND Although the mood stabilizing role of lithium is well established and the cognitive effects of lithium are also best demonstrated, but its primary effect on neurochemical profile and behaviors under stress remain ambiguous. Earlier studies have suggested that a single exposure to 2 h immobilization stress alters memory in various memory tasks, decreases exploratory activity in open field test and increases serotonin metabolism. This study is designed to investigate the stress relieving effect of lithium in rats. METHODS Rats were orally administered with lithium carbonate (1 mg/kg/ml) while controls received an equal volume of water for 21 days. After 21 days, each group of rats was sub-divided into stressed and unstressed groups. Animals of stressed group received immobilization stress for 2 h and 24 h following stress behavioral analysis was performed, after which animals were decapitated and their brain samples were collected for neurochemical estimation by HPLC-EC. RESULTS Results of the present study show that 2 h immobilization stress decreases locomotor activity while impairs memory performance. Prior administration of lithium attenuates memory impairment and locomotion suppressant effects of stress by reversing the stress induced brain serotonin metabolism in lithium treated rats. CONCLUSION Thus, the results of this study suggest that lithium may recover behavioral and neurochemical impairments induced by stress.

Chronic choline supplementation improves cognitive and motor performance via modulating oxidative and neurochemical status in rats

Abstract Choline, an essential nutrient, accounts for multiple functions in the body and brain. While its beneficial effects on healthy adults are not clear, choline supplementation is important during pregnancy for brain development, in elderly patients for support of cognitive performance and in patients with neurological disorders to reduce memory deficits. Thus, the aim of this study is to investigate whether choline administration in healthy adult rats beneficially impacts cognitive and locomotor performance, and associated oxidative and neurochemical outcomes. Two groups, control and choline, received tap water and choline bitartrate, respectively at the dose equivalent to adequate intake for five weeks. Food intake and body weight were monitored daily. Behavioral analysis comprising assessment of cognitive performance (by novel object recognition, passive avoidance and Morris Water Maze test) and locomotor performance (by Open field, Kondziela’s inverted screen and beam walking test) were performed. Following testing, rats were decapitated and brain samples were collected for estimation of acetylcholine, redox profile and monoamine measurements. The results showed that chronic choline administration significantly improves cognitive and locomotor performance accompanied by a reduction in oxidative stress, enhanced cholinergic neurotransmission and monoamine levels in the brain of healthy adult rats. Hence, chronic choline intake was found to improve behavioral, oxidative and neurochemical outcomes in the normal population, so it can be suggested that choline tablets can be used as a safe and effective supplement for improving the neurological health of normal individuals and that they might also be beneficial in preventing cognitive and motor disorders later in life. Graphical abstract No Caption available. HighlightsStudy was aimed to investigate whether choline intake is beneficial in healthy adults.Chronic choline intake at an adequate dose improved brain functioning in healthy adults.Chronic choline administration improved cognitive and locomotor function.Choline reduced oxidative stress, enhanced cholinergic and monoaminergic transmission.Hence, choline tablets may be suggested as a safer and effective supplement to improve neurological health.

Enhancement of hepatic trytophan pyrrolase activity and decreases of open field locomotion following single and repeated administration of high doses of caffeine in rats

In view of a possible role of kynurenine in caffeine-induced anxiety syndrome, the effects of single and repeated administration of caffeine on hepatic tryptophan (T)-pyrrolase activity are investigated. Single administration of caffeine at doses of 80 mg/kg decreased open field locomotion and increased hepatic T-pyrrolase activity. Locomotor stimulating effects of 80 mg/kg caffeine, monitored in the home cages of rats, were attenuated following daily administration of caffeine for 5 days. Open field locomotor activity of rats and its caffeine-induced decrement were also attenuated following 5 daily administrations of caffeine on the 6th day. Basal levels of hepatic T-pyrrolase activity increased after 5 daily administrations of caffeine on the 6th day. Acute administration of caffeine did not further elevate hepatic T-pyrrolase activity in 5 day caffeine injected rats. Drug adjuvants decreasing hepatic T-pyrrolase activity may prove valuable for extending the clinical utility of caffeine.