Nutritional importance of tryptophan for improving treatment in depression and diabetes

The importance of nutrients in our diet is becoming increasingly recognized. From the viewpoint of protein synthesis and other physiologic and metabolic functions, all amino acids are important, but some of these amino acids are not synthesized endogenously. This subset, called essential amino acids, comprise dietarily indispensable nutrients. Tryptophan, an essential amino acid, is the sole precursor of neuronal as well as peripheral serotonin (5-hydroxytryptamine). Its systemic or oral administration increases serotonin synthesis because tryptophan hydroxylase, the rate-limiting enzyme of 5-hydroxytryptamine biosynthesis, is physiologically unsaturated with its substrate. Central serotonin is implicated in a number of psychiatric illnesses, including depression, and in responses to stress. Acting peripherally, serotonin affects vasoconstriction, intestinal motility, control of T cell–mediated immunity, and liver and pancreatic functions. Depression and diabetes are 2 highly prevalent diseases that often coexist. There is evidence that occurrence of depression is 2–3 times higher in people with diabetes mellitus. A comorbid condition of diabetes and depression worsens the treatment and increases risk for death. Stress, known for its causal role in depression, can also enhance risk for diabetes. Stress-induced decreases in the circulating levels of tryptophan can impair brain and pancreatic serotonin-dependent functions to precipitate these diseases. The importance of tryptophan supplementation for improving therapeutic intervention in depression and diabetes is the focus of this article. A deficiency of this essential amino acid may enhance risk for depression as well as diabetes, and can also weaken treatment efficacy of medicinal compounds for treating these diseases. Guidelines for optimal levels of circulating tryptophan can help if supplements of this amino acid can improve treatment efficacy.

Anxiolytic, anti-nociceptive and body weight reducing effects of L-lysine in rats: Relationship with brain serotonin an In-Vivo and In-Silico study

L-lysine (L-lys) had long been comprehended as an essential amino acid for humans. There were reports that the absence or inadequate availability of L-lys in the diet may lead to mental and physical impairments. The present study was designed to explore the effects of L-lys on body weight changes, cumulative food intake, anxiety-like behavior and pain perception in rats. 5-Hydroxytryptamine (5-HT, serotonin) metabolism, and tryptophan (Trp) levels in the midbrain (MB), hippocampus (HP), and prefrontal cortex (PFC) were also determined. Animals were treated with L-lys in doses of 0.5 g/kg and 1 g/kg for 20 days and behavioral studies were performed on day 1st and day 20th. After monitoring behaviors on day 20th, animals were killed to collect the serum and brain regions MB, HP and PFC. 5-HT metabolism and Trp levels were determined by HPLC-EC. The treatment produce no effect on food intakes but body weights were reduced. 20 days administration of L-lys produced an anxiolytic effect and increased exploratory activity on day 1st. Repeated administration of L-lys increased 5-HT levels in the PFC and HP. 5-Hydroxyindoleacetic acid (5-HIAA), the metabolite of 5-HT, decreased in the HP. Trp, the precourser of 5-HT, decreased in the PFC. Results suggested a decrease in 5-HT degredation in enhancing 5-HT levels. Results of in-silico analysis showed that lysine had a potential binding affinity for MAO (monoamine oxidase) A and B with an energy of (-4.8 kcal/mol and -5.3 kcal/mol) respectively. The molecular dynamic simulation study revealed the stability of L-lys after 10 ns for each protein. Conclusively, the present study showed that L-lys produced an anxiolytic effect and reduced body weight. These beneficial effects were associated with an increase in 5-HT levels in the PFC and HP. In-silico analysis suggested that 5-HT increase were due to the binding of L-lys with MAOs resulting in an inhibition of the degradation of monoamine.

Behavioral, Hormonal, and Serotonergic Responses to Different Restricted Feeding Schedules in Rats

To determine the effect of long-term restricted feeding schedules on behavior, serotonergic responses, and neuro-endocrine functions, metabolism of serotonin (5-HT) in the striatum, expression of serotonin-1A (5-HT1A) auto-receptor in the raphe nuclei and circulating levels of leptin and corticosterone were determined in female Wistar rats kept on excessive food restriction schedule. Due to a role of dietary deficiency of tryptophan (Trp) in influencing serotonergic neurotransmission, circulating levels of Trp were also determined. Estimations were done in 2 different restricted feeding models: time-restricted feeding (TRF) and diet restricted (DR). TRF animals were given access to food ad libitum only for 2 hours/day. The DR animals were given a small calculated amount of food each day. We found that chronic food restriction for 5 weeks cause a significant decrease in the body weight and produced hyperactivity in both, TRF and DR animals. Levels of Trp were declined in circulation and in the striatum. Similarly, the levels of 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were decreased in the striatum. Also, the expression of 5-HT1A auto-receptor was declined in the raphe nuclei. These changes in 5-HT metabolism and 5-HT1A auto-receptor expression were more profound in DR animals as compare to TRF animals. Similarly, hypoleptinemia and increased corticosterone found in both models was higher in DR animals. Effect of dietary deficiency of Trp in the modulation of striatal 5-HT metabolism and its consequences on circulating leptin and corticosterone are discussed.

Co-treatment with low doses of buspirone prevents rewarding effects of methylphenidate and upregulates expression of 5-HT1A receptor mRNA in the nucleus accumbens

Accumulating studies consistently show that methylphenidate (MPD), the first line drug for treating Attention-Deficit Hyperactivity Disorder (ADHD), is abused by patients to whom the drug is prescribed. Like other psychostimulants, only low doses of MPD improve cognitive performance while higher doses impair it. Preventing the use of high doses of MPD is important for retaining its therapeutic efficacy. Previously, it has been shown that performance in Morris water maze test is improved in rats treated, orally, with MPD in doses of 2.5 mg/kg; but higher doses (5 mg/kg) impair it. The present study is designed to monitor rewarding effects of 2.5 mg/kg MPD in conditioned place preference (CPP) paradigm and its potential inhibition in buspirone co-treated animals. Our results show that rewarding effects of MPD in CPP paradigm are prevented in rats co-treated with buspirone in doses of 0.1 and 0.3 mg/kg. Animals treated with MPD exhibit a downregulation of 5-HT1A receptor mRNA in the nucleus accumbens which is also prevented in rats co-treated with 0.1 and 0.3 mg/kg but not 1.0 and 2.0 mg/kg buspirone. Administration of buspirone in these doses is not rewarding in CPP test and upregulates 5-HT1A receptor mRNA in the nucleus accumbens. The findings suggest that co-use of low doses of buspirone can prevent rewarding effects of MPD to help retain its therapeutic efficacy.

Neurochemical and behavioral effects of fluoxetine on midazolam induce dependence in an animal model of addiction

In the present study we have monitored effects of repeated coadministration of fluoxetine with midazolam; a benzodiazepine (CNS depressant). It is the primary drug of choice for procedural sedation, preoperative sedation, and in emergency departments. Repeated administration of this drug is reported to have abuse potential and may cause this by increasing dopaminergic neurotransmission. Since an important role of serotonin is there in the pathophysiology of anxiety and addiction, administration of midazolam may involve altered 5-HT metabolism as well. Present study was designed to monitor effects of repeated administration of fluoxetine with midazolam. Effects of fluoxetine and midazolam coadministration were monitored on motor activities in familiar and novel environments, hot plate test, forced swim test, conditioned place preference test and levels of dopamine, 5-HT and their metabolites. Both midazolam (2.5mg/kg) and fluoxetine (1mg/kg) were administered orally for 12 days. Conditioned place preference test was performed on day 13. Rats were decapitated and whole brain samples were collected and stored at -70°C until neurochemical analysis by HPLC-EC. Findings from the present study show attenuation of midazolam-induced reinforcement upon repeated co-administration of fluoxetine. These could be implicated to increased therapeutic utility of midazolam and related benzodiazepines.

Elevated anxiety, hypoactivity, memory deficits, decreases of brain serotonin and 5-HT-1A receptors expression in rats treated with omeprazole

Omeprazole (OM) is one of the most prescribed drugs worldwide for the treatment of hyperacidity and gastric reflux. However, concerns regarding its safety have emerged recently, and the drug is reported to enhance the risk for anxiety and cognitive deficits, particularly in elderly patients. The present study investigated these adverse effects, if any, in adult male rats. Associated changes in brain serotonin (5-hydroxytryptamine; 5-HT) and dopamine metabolism and the expression of 5-HT-1A receptors in the raphe and hippocampus were also determined. The drug was injected i.p. in doses of 10 and 20 mg/kg for 15 days. Both doses of OM decreased motor activity in an open field and impaired learning and memory in the Morris water maze test. Anxiety monitored in an elevated plus maze test was enhanced in rats treated with 20 mg/kg OM only. The levels of 5-HT and its metabolite 5-hydroxyindoleacetic acid and of homovanillic acid, a metabolite of dopamine, determined by HPLC-EC, were decreased in the brain of OM treated rats. The expression of 5-HT-1A receptor, determined by qRT-PCR, was reduced markedly in the hippocampus and moderately in the raphe. Our results provide evidence that OM use can reduce raphe hippocampal serotonin neurotransmission to lead to anxiety/depression and cognitive impairment. There is a need for increased awareness and prescription guidelines for therapeutic use of OM and possibly also other proton pump inhibitors.

Prevention of diet restriction induced hyperactivity but not body-weight reduction in rats co-treated with tryptophan: relationship with striatal serotonin and dopamine metabolism and serotonin-1A auto-receptor expression

Anorexia Nervosa (AN) is an eating and behavioral disorder characterized with anxiety/depression, hyperactivity, behavioral impulsivity and psychosis. Most of the associated symptoms are related to the deficiency of serotonin (5-hydroxytryptamine: 5-HT) stores. A deficiency of 5-HT can modulate dopamine neurotransmission in the striatum to elicit hyperactivity and psychosis in AN patients. Also, the release and availability of 5-HT are modulated by serotonin-1A (5-HT1A) auto-receptor. The present study investigates the role of striatal metabolism of 5-HT and dopamine in precipitating hyperactivity in the rat model of diet restriction (DR) induced AN. The role of tryptophan (Trp) in influencing the 5-HT metabolism and the mRNA expression of 5-HT1A auto-receptor is also investigated. We find that long-term DR for 38 days reduces body-weight in rats and produces hyperactivity, similar to AN. This hyperactivity is characterized by declined striatal metabolism of both, dopamine and 5-HT. The mRNA expression of 5-HT1A auto-receptor in the raphe nuclei is also decreased. Trp co-treatment improves these deficiencies in monoamine metabolism and alleviates hyperactivity. Interestingly, DR-induced changes in body-weights are not effected by Trp co-treatment. The study suggests that the striatal metabolism of 5-HT and dopamine and mRNA expression of 5-HT1A auto-receptor has an important role in the pathogenesis of AN. The finding suggests that co-use of Trp can prevent precipitation of AN by normalizing 5-HT metabolism.

Brain serotonin in high-fat diet-induced weight gain, anxiety and spatial memory in rats

Objectives: Effects of high-fat diet (HFD) consumption on body weight gain and its consequences on anxiety, learning and memory, and serotonin metabolism (5-hydroxytryptamine; 5-HT) in the hypothalamus and hippocampus are determined in rats. Methods: Male Wister rats treated with HFD or normal diet (ND) for 12 weeks to monitor food intakes, body weight changes, activity in an open field, anxiety in an elevated plus maze and learning/memory in Morris water maze. Animals decapitated to collect serum for determining leptin by an ELISA kit. The hippocampus and hypothalamus dissected out for determining 5-HT, its metabolite 5-hydroxyindoleacetic acid (5-HIAA) and its precursor tryptophan by HPLC-EC. Results: Despite a significant decrease in the cumulative weekly food intake, gain in body weight was greater in HFD than ND treated rats. Total caloric intakes were not different in the two groups. The consumption of HFD resulted in an enhancement of exploratory activity and reduction in anxiety. It improved learning acquisition and memory retention but impaired reference memory. There was an attenuation of 5-HT in the hypothalamus, and an enhancement of 5-HT and 5-HIAA in the hippocampus, but no effect occurred on tryptophan levels in the hypothalamus or the hippocampus. Serum leptin levels increased in HFD treated animals. Conclusion: Serotonin acting via the hypothalamus and hippocampus is involved in HFD-induced weight gain, anxiety reduction and modulation of cognitive performance.

Dose related acute behavioral and neurochemical profile of pioglitazone

Diabetics are twice as likely to have depression. It's normal to have long periods of sadness and anxiety. Pioglitazone has important role in the inflammatory response, which suggests that it might have the associated anti-depressant effects being manifested by its anti-depressant profile which needs further exploration. Monitoring changes in behavioral and neurochemical profile of pioglitazone in a dose-dependent manner was the purpose of this study. Pioglitazone was injected to rats at the doses of 0mg/kg, 2.5mg/kg, 5mg/kg and 10mg/kg. Behavioral activities in open field, Skinner's box and elevated plus maze were monitored 20, 35 and 45 minutes respectively after pioglitazone injection. whole brain samples were collected following decapitation of rats one-hour after injection. Samples were kept at -70ºC till HPLC-EC analysis for neurochemical profile. Results show anxiogenic and sedative effects of pioglitazone at all three doses as indicated by Skinner's box, elevated plus maze activity and open field. Also there was an overall decreased dopamine metabolism and increased serotonin turnover. This suggests that diabetic patients using pioglitazone as a therapeutic option, may experience more potent effects of CNS depressants. Findings may help in extending therapeutics in diabetic patients suffering from anxiety and/or depression.

Glucocorticoids in the Physiological and Transcriptional Regulation of 5-HT1A Receptor and the Pathogenesis of Depression

There is growing increase in the global prevalence of depression, but treatment outcome of this highly disabling disease is not satisfactory. Many patients are not benefitted by the currently prescribed antidepressants-together with this partial remission is very common. Improving treatment strategies and developing better therapeutic agents for treating depression is therefore highly needed. Stress-related epigenetic changes play a critical role in the pathogenesis as well as treatment of depression. Stressful events activate hypothalamic-pituitary-adrenal axis to increase circulating levels of glucocorticoids (GCs), and a greater sensitivity to this fright and flight response increases risk of depression. A role of serotonin (5-hydroxytryptamine; 5-HT) in responses to stress and in the pathogenesis and treatment of depression is well established. Substantial evidence supports a critical role of 5-HT1A receptors in these effects of 5-HT. The present article targets stress-induced higher and sustained increases of GCs and mediated influences on the physiological as well transcriptional regulation of 5-HT1A receptors to evaluate their causal role in the pathogenesis of depression. It is suggested that synthetic compounds with antagonist activity for GC receptors and agonist activity for 5-HT1A receptors may prove better therapeutic agents for treating depression.

Apomorphine-induced sensitization in rats exposed to restraint stress: Relationship with adaptation to stress

Drug abuse and impaired adaptation to stress are inter-related. Drug abuse is more potentiated upon exposure to stress and an impairment to cope with stress may lead to depression. On the other hand, use of addictive compounds increase the vulnerability to depression by inhibiting the adaptation to stress. Present study investigates relationship between behavioral tolerance to repeated restraint stress and apomorphine-induced sensitization. Apomorphine was injected either before or after the restraint stress episode, to monitor drug-induced behavioral sensitization and place preference. Apomorphine-induced sensitization and place preference were enhanced if the drug is experiencing during restraint stress. Conversely, apomorphine-induced sensitization and place preference were attenuated if the drug is experiencing after restraint stress. It shows that apomorphine, if experienced during restraint stress, produces greater sensitization Conversely, sensitization effects of apomorphine are blocked in animals receiving apomorphine after the termination of restraint stress. The results tend to show that drug of abuse may be effective for the treatment but not prevention of stress-induced depression.

Restraint-induced behavioral deficits are attenuated or impaired by pre- or post-injection of apomorphine: A context-based study

Apomorphine, a psycho stimulant, has neuroprotective effects due to its ability to decrease oxidative stress. Stress-induced dopaminergic dysfunction might lead to posttraumatic stress disorder, depression and related disorders. This dopaminergic dysfunction is more pre-dominant in basal ganglia and prefrontal cortex. Targeting of this dysfunction by psychostimulants, involves elevating dopamine in these brain regions and reduction of stress. On the other hand, stress itself can aggravate addictive effects to psycho stimulants. Present study was therefore designed to monitor the role of apomorphine in the attenuation of stress-induced behavioral deficits. Rats were exposed to 2hr restraint stress either before or after the apomorphine administration, to monitor effects of apomorphine administration on stress-induced behavioral deficits. Stress-induced decreases in food intake, growth rate and elevated plus maze activity were exacerbated if apomorphine was experienced during restraint stress. Conversely, these behavioral deficits were attenuated if apomorphine was experienced after restraint stress. It shows that apomorphine, if experienced during restraint stress, produces greater behavioral deficits, while the same were attenuated in rats receiving apomorphine after the termination of restraint stress. Results suggest that apomorphine and possibly the other CNS stimulants may help to cope stress by attenuating stress-induced behavioral deficits, if experienced after stress.

Targeting Serotonin1A Receptors for Treating Chronic Pain and Depression

The association of chronic pain with depression is becoming increasingly recognized. Treating both the conditions together is essential for an effective treatment outcome. In this regard, it is important to identify a shared mechanism involved in the association of chronic pain with depression. Central serotonin (5-hydroxytryptamine; 5-HT) neurotransmission has long been known to participate in the processing of signals related to pain. It also plays a key role in the pathogenesis and treatment of depression. Although functional responses to serotonin are mediated via the activation of multiple receptor types and subtypes, the 5-HT1A subtype is involved in the processing of nociception as well as the pathogenesis and treatment of depression. This receptor is located presynaptically, as an autoreceptor, on the perikaryon and dendritic spines of serotonin-containing neurons. It is also expressed as a heteroreceptor on neurons receiving input from serotonergic neurons. This arti-cle targets the 5-HT1A receptors to show that indiscriminate activation of pre and postsynaptic 5-HT1A receptors is likely to produce no therapeutic benefits; biased activation of the 5-HT heteroreceptors may be a useful strategy for treating chronic pain and depression individually as well as in a comorbid condition.

Circulating leptin, cortisol and gender differences associated with anorexia or obesity in depression

Objectives: To assess the role of circulating cortisol and leptin in depression associated with anorexia or obesity.Methods: Two hundred and fifty depressed patients presenting to the outpatient clinic of a psychiatric hospital and 250 non-depressed healthy volunteers were included in the study. The subjects of both groups were sub-grouped based upon their gender and BMI. Serum cortisol and leptin were determined by using respective ELISA kits.Results: The number of depressed than non-depressed subjects was three-fold higher in obese BMI groups of both genders. There were more depressed than non-depressed subjects in the underweight male BMI groups and in the overweight female BMI groups. There was a BMI-related increase in serum leptin and a decrease in serum cortisol in both genders. Depression in underweight BMI groups of both genders was associated with a decrease in serum leptin and an increase in cortisol. Higher serum leptin in obese BMI group was associated with a decrease in serum cortisol.Conclusions: Obesity is a risk factor for depression. The shift from typical to atypical depression is due to an inhibitory effect of higher circulating leptin on HPA axis activity and subsequent decrease in the lipolytic effects of cortisol.

Neurochemical and behavioral effects of midazolam: A dose related study

In the present study we have monitored dose dependent effects of midazolam; a benzodiazepine (CNS depressant). It is the primary drug of choice for procedural sedation, preoperative sedation, and in emergency departments. Repeated administration of this drug is reported to have abuse potential and may cause this by increasing dopaminergic neurotransmission. Since an important role of 5-hydroxy tryptamine (5-HT) is there in the pathophysiology of anxiety and addiction, administration of midazolam may involve altered 5-HT metabolism as well. Present study was designed to monitor dose-dependent effects of midazolam and select the optimum dose for further experiments. Effects of midazolam were monitored on food intake, growth rate, activities in familiar and novel environments, light dark box activity, hot plate test, forced swim test and levels of dopamine, 5-HT and their metabolites. Midazolam was administered orally (0mg/kg, 2.5mg/kg, 5.0mg/kg and 10mg/kg) and behaviors were monitored post single midazolam administrations. Rats were decapitated and whole brain samples were collected and stored at -70°C until neurochemical analysis by HPLC-EC. Findings from the present study could be implicated to increased therapeutic utility of midazolam and related benzodiazepines.

Enhancement and impairment of cognitive behaviour in Morris water maze test by methylphenidate to rats

Methylphenidate (MPD), a psycho-stimulant is a prescription medicine for the treatment of Attention deficit hyperactivity disorder (ADHD). The drug is also being increasingly used by general population for enhancing cognition. Only few preclinical studies have been carried out on the effects of MPD on cognition and these studies show either an enhancement or impairment of memory following the administration of MPD. The present study was designed to evaluate the effects of different doses of methylphenidate on acquisition and retention of memory in Morris water-maze test. Twenty four male Albino Wistar rats (weighing 180-220gm) were randomly assigned to four groups: (1) Control (2) 0.5mg/kg (3) 2.5mg/kg (4) 5 mg/kg methylphenidate. Animals received drug or water orally before training phase. Memory acquisition was monitored 2hrs post drug administration while memory retention was determined next day. It was found that the clinically relevant doses of methylphenidate (0.5mg/kg and 2.5mg/kg) improved memory acquisition and its retention but higher dose (5mg/kg) impaired both. We suggest that MPD-induced increase of catecholamine neurotransmission may have a role in the improvement of water maze performance while agonist activity of the drug for 5HT-1A receptor in the impaired performance at high doses. Food intake and body weight changes were not affected by MPD administration due to short-term administration of the drug. Results may help in improving pharmaco-therapeutic use of MPD for ADHD.

Repeated treatment with a low dose of reserpine as a progressive model of Parkinson's dementia

Present study was designed to monitor the cognitive profile of the animals upon repeated administration of reserpine, so as to determine that whether these animals should be used as animal models of Parkinson's dementia. In the present study, reserpine was injected daily (once a day for three weeks) at the dose of 0.1mg/kg. Short- and long term memories were assessed using a Morris water maze, on weekly basis. Novel object recognition test was performed after completion of the treatment (day 21). Animals were decapitated on day 21 and brain samples were stored at -70ºC until neurochemical analysis by HPLC-EC. Impairment of short- and long term activities (as monitored in Morris water maze) were not observed until after first week. Long term memory was found to be impaired earlier than the short term memory. Novel object recognition test also exhibited reserpine-induced impairment of working memory. Neurochemical analysis of the whole brain samples by HPLC-EC method showed that repeated administration of reserpine significantly increased DOPAC/ DA ratio (p<0.01). While 5-HIAA/ 5-HT ratio was found to be decreased (p<0.05) in reserpine injected animals. This further confirmed that these neurochemical deficits to be the underlying reason in memory impairment. In conclusion, present study provides evidence that repeated administration of reserpine can be used as a 'progressive' animal model of Parkinson's dementia. Results could be beneficial for face validity and screening of the drugs for the treatment of dementia secondary to Parkinson's and related disorders.

Dopamine and serotonin metabolism associated with morphine reward and its inhibition with buspirone: A study in the rat striatum

Adaptations within the nucleus accumbens (NAc) and caudate nucleus (CN) dopamine neurotransmission are involved in behavioral sensitization and enhanced incentive motivation towards drug paired stimuli which lead to drug addiction. Serotonin (5-hydroxytryptamine; 5-HT) can modulate dopamine neurotransmission to reduce rewarding effects of drugs of abuse. A recent study from our laboratory shows that rewarding effects of morphine are inhibited in rats co-treated with buspirone. To understand the neurochemical mechanism involved in morphine addiction and its inhibition with buspirone, present study determines the effects of buspirone, morphine and their co-administration on the metabolism of serotonin and dopamine in the NAc and CN. We find that rewarding effects of morphine are associated with an enhancement and attenuation of dopamine metabolism, respectively in the CN and NAc. Serotonin metabolism is enhanced in both regions. Co-administration of buspirone not only prevents rewarding effects of morphine, but its effects on the metabolism of dopamine and serotonin in the NAc and CN are also reversed. Results suggest that 5-HT1A receptor dependent modulation of dopamine neurotransmission in the CN and NAc is involved in the modulation of the rewarding effects of morphine in buspirone co-treated animals. The findings documenting an important role of 5-HT1A receptors in drug addiction suggest that synthetic opioid drugs with agonist activity of 5-HT1A receptors may prove non addictive analgesics.

Effects of single administration of apomorphine on memory and monoamine metabolism: A dose related study

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, & 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, & 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°C. Biogenic amines (i.e., 5-Hydroxytryptamine; 5-HT and dopamine) and metabolites (i.e., Dihydroxyphenylacetic acid; DOPAC, Homovanillic acid; HVA & 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.

Walnut supplementation reverses the scopolamine-induced memory impairment by restoration of cholinergic function via mitigating oxidative stress in rats: a potential therapeutic intervention for age related neurodegenerative disorders

The brain is highly susceptible to the damaging effects of oxidative reactive species. The free radicals which are produced as a consequence of aerobic respiration can cause cumulative oxygen damage which may lead to age-related neurodegeneration. Scopolamine, the anti-muscarinic agent, induces amnesia and oxidative stress similar to that observed in the older age. Studies suggest that antioxidants derived from plant products may provide protection against oxidative stress. Therefore, the present study was designed to investigate the attenuation of scopolamine-induced memory impairment and oxidative stress by walnut supplementation in rats. Rats in test group were administrated with walnut suspension (400 mg/kg/day) for four weeks. Both control and walnut-treated rats were then divided into saline and scopolamine-treated groups. Rats in the scopolamine group were injected with scopolamine (0.5 mg/kg dissolved in saline) 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 task (NOR) followed by estimation of regional acetylcholine levels and acetylcholinesterase activity. In the next phase, brain oxidative status was determined by assaying lipid peroxidation, and measuring superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities. Results showed that scopolamine-treatment impaired memory function, caused cholinergic dysfunction, and induced oxidative stress in rats compared to that saline-treated controls. These impairments were significantly restored by pre-administration of walnut. This study demonstrates that antioxidant properties of walnut may provide augmented effects on cholinergic function by reducing oxidative stress and thus improving memory performance.

Antioxidant effects of rice bran oil mitigate repeated haloperidol-induced tardive dyskinesia in male rats

Tardive dyskinesia (TD) is associated with the use of antipsychotic drugs such as D2 antagonist haloperidol (HP). The chronic use of HP is involved in the causation of free radicals and/or oxidative stress. In view of the nootropic, anti-anxiety, anti-inflammatory-like effects of rice bran oil (RBO) in a variety of investigations, we assessed the protective properties of RBO on HP-induced TD and neurochemical alteration. Rats treated with HP orally at a dose of 0.2 mg/kg/day for a period of 5 weeks developed VCMs which increased progressively as the treatment continued for 5 weeks. Co-administration of RBO by oral tubes at a dose of 0.4 ml/day prevented the induction of HP-induced VCMs. Repeated administration of HP increases the turnover of dopamine metabolism in the striatum. Conversely animals treated with HP + RBO decrease the metabolism of DA than water + HP treated animals. Striatal, malondieldehyde (MDA), hydrogen peroxide (H₂O₂) and antioxidant enzyme superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were also determined. It is suggested that beneficial role of RBO in attenuation of HP-induced TD. The results therefore recommended that supplementation of RBO may be useful in the HP-induced TD. The findings have also potential implication in the treatment of schizophrenia and motor disorders.

Fasting leptin and glucose in normal weight, over weight and obese men and women diabetes patients with and without clinical depression

A large number of diabetes patients suffer from major depression and are at high risk of mortality. In view of a role of leptin in diabetes, depression and energy homeostasis, the present study concerns circulating levels of leptin in different BMI groups of un-depressed and depressed diabetes patients. Six hundred thirty male and female patients with a primary diagnosis of diabetes were grouped according to BMI and with or without clinical symptoms of depression. Age matched healthy, normal weight male and female volunteers without clinical symptoms of depression or diabetes were taken as controls. Blood samples were obtained after an overnight fast of 12 h. Serum was stored for the determination of leptin and glucose. We found that there were more female than male diabetes patients with comorbid depression. Fasting leptin was higher in normal weight non-diabetes women than men; but comparable in normal weight men and women diabetes patients. Fasting glucose levels were higher in diabetes than non diabetes groups; values were comparable in men and women. Depression was associated with a decrease and increase in leptin respectively in normal-overweight and obese men and women diabetes patients. Glucose levels were also higher in obese depressed than un-depressed diabetes patients. The results suggested that the female gender is at greater risk to comorbid diabetes with depression. Adipo-insular axis plays an important role in diabetes, associated depression and in the greater risk of the female gender to comorbid diabetes with depression.

Improving therapeutics in anorexia nervosa with tryptophan

A growing body of evidence suggests that our diet is an important contributing factor in the development, management and prevention of a number of psychiatric illnesses. Tryptophan, an essential amino acid, is the sole precursor of neurotransmitter 5-hydroxytryptamine (5-HT; serotonin). Administration of tryptophan can boost serotonin neurotransmission to produce therapeutically important effects in serotonin deficiency disorders. Anorexia nervosa (AN) an eating disorder associated with high levels of psychiatric comorbidity including psychosis, hyperactivity, depression and anxiety has highest lethality of all psychiatric illnesses. Evidence suggests that excessive dieting and food restriction can decrease brain tryptophan and serotonin in AN patients to precipitate depression, psychosis and hyperactivity. There are currently no FDA approved pharmacological treatments available for AN patients; antidepressants and antipsychotics, largely used to treat associated psychiatric comorbidities are also not very effective. The aim of this non-systematic review article is to evaluate and document a potential importance of tryptophan supplementation in improving therapeutics in AN patients.

New isatin derivative inhibits neurodegeneration by restoring insulin signaling in brain

Diabetes is associated with neurodegeneration. Glycation ensues in diabetes and glycated proteins cause insulin resistance in brain resulting in amyloid plaques and NFTs. Also glycation enhances gliosis by promoting neuroinflammation. Currently there is no therapy available to target neurodegenration in brain therefore, development of new therapy that offers neuroprotection is critical. The objective of this study was to evaluate mechanistic effect of isatin derivative URM-II-81, an anti-glycation agent for improvement of insulin action in brain and inhibition of neurodegenration. Methylglyoxal induced stress was inhibited by treatment with URM-II-81. Also, Ser473 and Ser9 phosphorylation of Akt and GSK-3β respectively were restored by URM-II-81. Effect of URM-II-81 on axonal integrity was studied by differentiating Neuro2A using retinoic acid. URM-II-81 restored axonal length in MGO treated cells. Its effects were also studied in high fat and low dose streptozotocin induced diabetic mice where it reduced RBG levels and inhibited glycative stress by reducing HbA1c. URM-II-81 treatment also showed inhibition of gliosis in hippocampus. Histological analysis showed reduced NFTs in CA3 hippocampal region and restoration of insulin signaling in hippocampii of diabetic mice. Our findings suggest that URM-II-81 can be developed as a new therapeutic agent for treatment of neurodegenration.

Co-treatment with imipramine averted haloperidol-instigated tardive dyskinesia: Association with serotonin in brain regions

Outcome of imipramine (IMI) treatment was scrutinized on progression of haloperidol instigated tardive dyskinesia (TD). 0.2 mg/kg/rat dosage of haloperidol provided orally to rats for 2 weeks enhanced vacuous chewing movements that escalated when the process proceeded for 5 weeks. Following 2 weeks co-injection 5 mg/kg dosage of IMI was diminished haloperidol-instigated VCMs and fully averted following five weeks. The potency of 8-OH-DPAT-instigated locomotor activity exhibited higher in saline+haloperidol treated rats while not observed in IMI+ haloperidol treated rats. 8-OH-DPAT-instigated low 5-hydroxytryptamine (5-HT; serotonin) metabolism was higher in saline+ haloperidol treated rats when compare to IMI+ haloperidol treated rats in both regions of brain (striatum and midbrain). It is recommended that IMI possibly competent in averting TD, in cases receiving treatment to antipsychotics.

Nigella sativa Oil Reduces Extrapyramidal Symptoms (EPS)-Like Behavior in Haloperidol-Treated Rats

The symptoms of Parkinsonism and oral dyskinesia have been showing to be induced by neuroleptics that significantly affect its clinical use. In this study, we investigate whether Nigella sativa-oil (NS) (black cumin seeds)-a traditional medicine used for the seizure treatment in eastern country-may reduce the haloperidol (HAL)-induced extrapyramidal symptoms (EPS)-like behavior in rats. After combine treatment with HAL (1 mg/kg) on NS (0.2 ml/rat), rats displayed a significant decreased EPS-like behavior including movement disorders and oral dyskinesia as compared to controls. Immunohistochemical analysis indicates that NS reduced astrogliosis in caudate and accumbens nuclei. These results suggest that NS may consider as an adjunct to antipsychotics to reduce the EPS-like side effect.

Report: Protective effects of rice bran oil in haloperidol-induced tardive dyskinesia and serotonergic responses in rats

Effect of administration of Rice bran oil (RBO) was evaluated on haloperidol elicited tardive dyskinesia in rats. Albino Wistar rats treated with haloperidol in drinking water at a dose of 0.2mg/kg/day and RBO by oral tubes at a dose of 0.4 mL/day for 5 weeks. Motor coordination, VCMs and 8-hydroxy-2-(di-n-propylamino) tetraline)[8-OH-DPAT] _syndrome were monitored. Striatal serotonin (5-hydroxytryptamine; 5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels were determined by high performance liquid chromatography (HPLC-EC). Rats treated with haloperidol orally at a dose of for a period of 5 weeks developed VCMs, which increased progressively as the treatment continued for 5 weeks. Motor coordination impairment started after the 1st week and was maximally impaired after 3 weeks and gradually returned to the 1st week value. Co-administration of RBO prevented haloperidol_induced VCMs as well impairment of motor coordination. The intensity of 8-OH-DPAT_induced syndrome and decreased 5-HT metabolism were greater in water + haloperidol treated animals than RBO + haloperidol treated animals. The present study suggested that involvement of free radical in the development of TD and point to RBO as a possible therapeutic option to treat this hyperkinetic motor disorder.

Effects of sugar rich diet on brain serotonin, hyperphagia and anxiety in animal model of both genders

Lower levels of 5-hydroxytryptamine (5-HT; serotonin) in the brain elicit sugar craving, while ingestion of sugar rich diet improves mood and alleviates anxiety. Gender differences occur not only in brain serotonin metabolism but also in a serotonin mediated functional responses. The present study was therefore designed to investigate gender related differences on the effects of long term consumption of sugar rich diet on the metabolism of serotonin in the hypothalamus and whole brain which may be relevant with the hyperphagic and anxiety reducing effects of sugar rich diet. Male and female rats were fed freely on a sugar rich diet for five weeks. Hyperphagic effects were monitored by measuring total food intake and body weights changes during the intervention. Anxiolytic effects of sugar rich diet was monitored in light-dark transition test. The results show that ingestion of sugar rich diet decreased serotonin metabolism more in female than male rats. Anxiolytic effects were elicited only in male rats. Hyperphagia was comparable in both male and female rats. Finings would help in understanding the role of sugar rich diet-induced greater decreases of serotonin in sweet craving in women during stress.

Apomorphine induced conditioned place preference and sensitization is greater in rats exposed to unpredictable chronic mild stress

CNS stimulants are the class of the drugs that may be used to get relief from depression. Apomorphine is a D1 and D2 receptor agonist with a CNS stimulatory effect used for the treatment of Parkinson's disease is also abused. Although many drugs of abuse produce tolerance and dependence. Long term use of pshycostimulants produce reverse tolerance described as sensitization. These drugs also have a number of other beneficial effects but their therapeutic use is limited because of abuse potential. Conditioned place preference (CPP) test is used to monitor the reinforcing effect of drugs of abuse. Stress is an important factor that precipitates and potentiates addictive effects of different drugs of abuse. The present study was designed to investigate the addictive effect of apomorphine (1mg/kg) in rats previously exposed to repeated unpredictable chronic mild stress for 10 days (animal model of depression). Results from present study illustrate that unpredictable chronic mild stress potentiates the reinforcing effects of apomorphine as the number of entries and the time spent in the CPP compartment associated with drug administration is increased. Motor activity was taken as a parameter for behavioral sensitization which is induced by repeated administration of apomorphine, monitored as the number of cage crossings in light compartment of the CPP apparatus, also increased.

Nootropic and anti-stress effects of rice bran oil in male rats

Rice bran oil (RBO) is an important product of rice bran. It is considered to be one of the most important nutritious oil due to its favorable fatty acid composition and unique composition of naturally occurring biologically active antioxidant compounds. This study was designed to monitor the effects of oral intake of RBO on stress response in rats. RBO was extracted using hexane. Rats were divided into Control and test (RBO-treated). RBO-treated rats were given 0.2 ml/day RBO for 6 weeks. Food intake and body weight changes were monitored weekly. After 6 weeks open field activity and Morris Water Maze (MWM) test were performed. Results showed that weekly cumulative food intake but not body weight were lower in RBO-treated rats during 1st to 5th week of treatment, which were normalized at the end of treatment. Exploratory activity of RBO-treated rats in an open field was increased. Spatial memory in Morris water maze was enhanced in RBO-treated than control rats. An episode of 2 h restraint stress decreased the 24 h food intake of both control and RBO-treated animals. Behavioral deficits were lower in RBO-treated rats. Exposure of 2 h restraint stress increased brain serotonin (5-hydroxytryptamine: 5-HT) metabolism. These increases were lower in RBO-treated restrained than their respective control animals. Serotonergic neurotransmitter mechanism is implicated in stress. The findings of the study show beneficial effects of RBO in learning and memory functions. Moreover, the study also highlights the attenuating effect of RBO on stress induced behavioral and neurochemical effects in rats.

Immobilization-induced increases of systolic blood pressure and dysregulation of electrolyte balance in ethanol-treated rats

Clinical and experimental studies revealed that alcohol drinking and life event stresses are predisposing factors to hypertension. Intra and extra cellular levels of electrolytes may play important role in the pathogenesis and treatment of hypertension. Dietary intake of sodium, potassium, calcium and magnesium is suggested to have a role in the regulation of blood pressure. The present study was designed to monitor the effects of acute exposure to 2h immobilization stress and ethanol administration at a dose of 2.5 g/kg body weight (i.p.) and combined effect of acute administration of ethanol and immobilization stress on systolic blood pressure (SBP), intraerythrocyte, serum and tissue electrolytes in rats. Results showed that acute exposure to 2h immobilization increased SBP, intraerythrocyte sodium and decreased intraerythrocyte potassium in water as well as in ethanol injected rats. The concentration of Na⁺ and Ca²⁺ increased while that of K⁺ and Mg²⁺ decreased in the heart and kidney tissue. Ethanol administration also increased Na⁺ and Ca²⁺ levels and decreased K⁺ and Mg²⁺ levels in the heart and kidney tissue. Restraint stress decreased serum levels of Na⁺, K⁺, Ca²⁺, P, and Cl⁻ and increased serum Mg²⁺, glucose and haematocrit. Ethanol administration also decreased serum levels of Na⁺, K⁺, Ca²⁺, P, and Cl⁻ and increased serum Mg²⁺, glucose and haematocrit. The effects of ethanol and stress on the changes of blood and tissues electrolytes were additive and may be involved in the greater occurrence of hypertension in alcoholics. Our results suggested an important role of intra and extra cellular electrolytes in both stress and ethanol-induced hypertension. The findings may help to develop strategies for the treatment of hypertension in alcoholics.

Behavioral deficits in rats following acute administration of glimepiride: Relationship with brain serotonin and dopamine

A considerable body of literature suggests that depression and diabetes mellitus are co-morbid. The present study was designed to test any possible behavioral deficits and/or neurochemical changes in the brain as induced by the anti-diabetic drugs. Twenty-four rats were divided into four groups: (i) saline (ii) glimepiride (2.5mg/kg)- (iii) glimepiride (5.0mg/kg)- and (iv) glimepiride (10 mg/kg) injected animals. Behavioral activities in Skinner's box, open field and elevated plus maze were monitored 20, 35 and 45 minutes post injection respectively. Animals were decapitated 60 minutes post injection to collect brain samples. Samples were kept at -70°C until neurochemical analysis by HPLC-EC. Results from the present study show decreased time spent in the open arm of the elevated plus maze (p<0.05) at all the three doses. A decrease in the HVA (Homovanillic acid) levels at all three doses (p<0.01) was also observed along with decreased 5-HT (5-Hydroxytryptamine) (p<0.05 at 5.0 and 10mg/kg) and 5-HIAA (5-Hydroxyindoleacetic acid) (p<0.05 at all three doses) levels. Since a decrease in 5-HT metabolism can induce depression-like effects, the present study therefore suggests that the occurrence of depression in diabetic patients is due to the use of glimipride. Effects of long-term administration of smaller doses of glimipride are to be explored further to monitor tolerance in glimipride-induced deficits of serotonin. The finding may help to explore the cause of depression in diabetics for improving pharmacotherapy in diabetes.

Dose-dependent effects of tryptophan on learning and memory

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 1h of this 2nd 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.

Haloperidol-induced extra pyramidal symptoms attenuated by imipramine in rats

Effects of administration of imipramine (IMI) are determined on haloperidol-induced extrapyramidal symptoms (EPS). Haloperidol is administered orally at a dose of 0.2 mg/rat/day in rats for a period of 5 weeks, by this treatment rats developed vacuous chewing movements (VCMs) after 2 weeks, which increased in a time dependent manner 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.

Unpredictable chronic mild stress induced behavioral deficits: a comparative study in male and female rats

Stress is an important precipitant factor for depression. Changes in various body systems that occur in depression are similar to those observed in response to stress. Chronic stress may alter behavioral, neurochemical and physiological responses to drug challenges and novel stressors. Unpredictable chronic mild stress (UCMS) also produces alteration in the serotonergic (5-HT; 5-hydroxytryptamine) neurotransmission. Unpredictable chronic mild stress (UCMS) could be used as an animal model of depression. Neurochemical and behavioral effects of UCMS can be reversed by antidepressant agents, suggesting an important role of serotonin. In rodents, UCMS can elicit depression-like symptoms. The objective of the present study was to evaluate and compare the behavioral deficits induced by chronic mild stress in male and female rats and finding out the vulnerability of the two groups. Male and female rats exposed to UCMS exhibited a significant decrease in cumulative food intake as well as in growth rate. Loco motor activity in home cage and open field was also decreased. Results may contribute to our understanding of the interaction between stress and behavioral functions have to depressive disorders.

Nootropic and hypophagic effects following long term intake of almonds (Prunus amygdalus) in rats

INTRODUCTION

Over a period of time researchers have become more interested in finding out the potential of various foods to maintain the general health and to treat diseases. Almonds are a very good source of many nutrients which may help to sharpen the memory and to reduce cardiovascular risk factors.

OBJECTIVE

The present study was conducted to evaluate the nootropic effects of almonds. Effect of oral intake of almond was also monitored on food intake and plasma cholesterol levels.

METHODS

Rats were given almond paste orally with the help of feeding tube for 28 days. Memory function in rats was assessed by Elevated Plus Maze (EPM) and Radial Arm Maze (RAM). Brain tryptophan, 5-HT and 5-HIAA were estimated at the end of the treatment by HPLC-EC method.

RESULTS

A significant improvement in learning and memory of almond treated rats compared to controls was observed. Almond treated rats also exhibited a significant decrease in food intake and plasma cholesterol levels while the change in growth rate (in terms of percentage) remained comparable between the two groups. Analysis of brain tryptophan (TRP) monoamines exhibited enhanced TRP levels and serotonergic turnover in rat brain following oral intake of almonds.

CONCLUSION

The findings show that almonds possess significant hypophagic and nootropic effects. Results are discussed in context of enhanced 5-HT metabolism following almond administration.

Extending therapeutic use of psychostimulants: focus on serotonin-1A receptor

INTRODUCTION

Despite a number of medicinally important pharmacological effects, the therapeutic use of psychostimulants is limited because of abuse potential and psychosis following long term use. Development of pharmacological agents for improving and extending therapeutic use of psychostimulants in narcolepsy, attention deficit hyperactivity disorder, Parkinson's disease, obesity and as cognitive enhancer is an important research imperative. In this regard, one potential target system is the 5-hydroxytryptamine (5-HT; serotonin) neurotransmitter system. The focus of the present article is to evaluate a potential role of 5-HT-1A receptor in the alleviation of abuse potential and psychosis-induced by prescription psychostimulants amphetamines and apomorphine.

METHOD

Synaptic contacts between dopamine systems and 5-HT-1A receptors are traced. Studies on serotonin-1A influences on the modulation of dopamine neurotransmission and psychostimulant-induced behavioral sensitization are accumulated.

RESULTS

Inhibition of amphetamine and apomorphine-induced behavioral sensitization by co administration of 5-HT-1A agonists cannot be explained in terms of direct activation of 5-HT-1A receptors, because activation of pre- as well as postsynaptic 5-HT-1A receptors tends to increase dopamine neurotransmission.

CONCLUSION

Long term use of amphetamine and apomorphine produces adaptive changes in 5-HT-1A receptor mediated functions, which are prevented by the co-use of 5-HT-1A agonists. In view of extending medicinal use of psychostimulants, it is important to evaluate the effects of co-use of 5-HT-1A agonists on potential therapeutic profile of amphetamine and apomorphine in preclinical research. It is also important to evaluate the functional significance of 5-HT-1A receptors on psychostimulant-induced behaviors in other addiction models such as drug self-administration and reinstatement of drug seeking behavior.

Neurochemical and behavioral effects of green tea (Camellia sinensis): a model study

Being rich in polyphenolic compounds such as flavonoids, green tea is suggested to be a potential candidate for the treatment of obesity, stress, depression, Parkinson's and other disorders. Since serotonin has an important role in the pathophysiology of these disorders, present study was designed to monitor the effects of green tea in rats. Green tea extract was provided to the male Albino Wistar rats for 5 weeks, and effects on behaviors were monitored. Results show a decrease in food intake after 5th week but not before. An increase in locomotive activities of the animals was observed, as monitored in novel as well as in familiar environment. Anxiolytic effects were observed in elevated plus maze but not in light dark activity box. An increase in dopamine and serotonin turnover was observed. Our results suggest that beneficial effects of green tea drinking might be due to alteration of serotonin and/or dopamine metabolism. We thereby propose that in further experiments, green tea should be administered in animal model of learned helplessness and effects on the development of adaptation to stress should be monitored. Neurochemical estimations of catecholamine and indoleamine in these animal models of stress exposed to green tea would help in understanding the anxiolytic effects of green tea.

Oral administration of haloperidol at clinically recommended doses elicits smaller parkinsonian effects but more tardive dyskinesia in rats

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.

Decreased Hippocampal 5-HT and DA Levels Following Sub-Chronic Exposure to Noise Stress: Impairment in both Spatial and Recognition Memory in Male Rats

Mankind is exposed to a number of stressors, and among them noise is one which can cause intense stress. High levels of background noise can severely impair one’s ability to concentrate. The present study was aimed to investigate the effect of sub-chronic noise stress on cognitive behavior and hippocampal monoamine levels in male rats. The study was performed on 12 male Wistar rats, divided into two groups; the control and noise-exposed. The rats in the test group were subjected to noise stress, 4h daily for 15 days. Cognitive testing was performed by the Elevated Plus Maze test (EPM) and Novel Object Recognition test (NOR). HPLC-EC was used to determine hippocampal monoamine levels and their metabolites. The data obtained revealed a significant decrease in hippocampal serotonin (5-hydroxytryptamine; 5-HT) and dopamine (DA) levels, whereas turnover ratios of 5-HT and DA were significantly increased compared to the controls. Rats exposed to noise exhibited a significant decrement in spatial memory. A significantly decreased recognition index of rats exposed to noise as compared to the control was also observed in the NOR test. Results of the present findings suggest the role of decreased hippocampal 5-HT and DA in the impairment of cognitive function following noise exposure.

Behavioral and neurochemical profile of some novel phenacyl based isonipecotamide derivatives

Study of natural products led to the development of new molecules of potential biological activity. Piperidine nucleus constitutes one of the components of various alkaloids and drugs. During the course of our project regarding the synthesis of derivatives of piperidine carboxamide to study the effects of these compounds as anti-depressive agents, some of the compounds exhibited significant effects at all three doses, through open field activity thus establishing a direct relationship between dose and locomotion. Moreover, these compounds have also shown the decreased level of 5-HT alone with increased level of dopamine as an indication of their antagonism towards 5-HT receptor.

Raphe-Hippocampal Serotonin Neurotransmission In The Sex Related Differences of Adaptation to Stress: Focus on Serotonin-1A Receptor

Stress is the major predisposing and precipitating factor in the onset of depression which is the most significant mental health risk for women. Behavioral studies in animal models show that female sex though less affected by an acute stressor; exposure to repeated stressors induces coping deficits to impair adaptation in them. A decrease in the function of 5-hydroxytryptamine (5-HT; serotonin) in the hippocampus and an increased function of the 5-HT-1A receptor in the raphe nucleus coexist in depression. Pharmacological and neurochemical data are relevant that facilitation of serotonin neurotransmission via hippocampus due to desensitization of somatodendritic 5-HT1A receptors may lead to adaptation to stress. The present article reviews research on sex related differences of raphe-hippocampal serotonin neurotransmission to find a possible answer that may account for the sex differences of adaptation to stress reported in preclinical research and greater incidence of depression in women than men.

Regional neurochemical profile following development of apomorphine-induced reinforcement

Dopamine is primary neurotransmitter which mediates the reinforcing effects of abused drugs, serotonin (5-Hydroxytryptamine; 5-HT) also has a crucial role in the pathophysiology of addiction. The binding sites of various drugs of abuse are different from each other, their final rewarding effects are mediated by an increase in the dopamine level in the Nucleus Accumbens. The present study used conditioned place preference (CPP) test to monitor apomorphine's reinforcing effects. Associated alterations in 5-HT and dopamine metabolism were also monitored in various brain regions by HPLC-EC. Withdrawal from apomorphine administration (at a dose of 1.0 mg/kg on six alternate days) induced reinforcement as monitored in the conditioned place preference (CPP) paradigm. Serotonin and dopamine metabolism was also changed particularly in the ventral and dorsal striatum. Results therefore suggest desensitization of dopamine receptors in the presynaptic site is involved in apomorphine-induced reinforcement. Desensitization of somatodendritic 5-HT(1A) receptors resulting in increased availability of 5-HT at 5-HT(2C) receptors could attenuate apomorphine-induced reinforcement. Therefore, further investigations in this area should focus on attempts to attenuate apomorphine-induced reinforcement by desensitizing somatodendritic 5-HT(1A) receptors.

Altered brain serotonergic neurotransmission following caffeine withdrawal produces behavioral deficits in rats

Caffeine administration has been shown to enhance performance and memory in rodents and humans while its withdrawal on the other hand produces neurobehavioral deficits which are thought to be mediated by alterations in monoamines neurotransmission. A role of decreased brain 5-HT (5-hydroxytryptamine, serotonin) levels has been implicated in impaired cognitive performance and depression. Memory functions of rats were assessed by Water Maze (WM) and immobility time by Forced Swim Test (FST). The results of this study showed that repeated caffeine administration for 6 days at 30 mg/kg dose significantly increases brain 5-HT (p<0.05) and 5-HIAA (p<0.05) levels and its withdrawal significantly (p<0.05) decreased brain 5-HT levels. A significant decrease in latency time was exhibited by rats in the WM repeatedly injected with caffeine. Withdrawal of caffeine however produced memory deficits and significantly increases the immobility time of rats in FST. The results of this study are linked with caffeine induced alterations in serotonergic neurotransmission and its role in memory and depression.

Effects of apomorphine on locomotive activity and monoamine metabolism: a dose related study

We have monitored dose dependent effects of apomorphine on motor activity and monoamine metabolism. 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., 1.0, 2.0 & 4.0 mg/kg) on exploration in a novel environment (open field) and locomotion in a familiar environment (home cage) were investigated. Results show significantly enhanced activity in home cage (monitored 5min post injection) in a dose dependent manner. However, no significant influence of apomorphine on exploration of open field was observed in the present study (monitored 15 min and 40 min post injection). Animals were decapitated 1 hr post apomorphine injection and whole brains of animals were collected and stored at -70°C. Biogenic amines (i.e., 5-Hydroxytryptamine and dopamine) and metabolites (i.e., Dihydroxyphenylacetic acid, Homovanillic acid & 5-Hydroxyindoleacetic acid) were estimated by reverse phase High Performance Liquid Chromatography with electrochemical detector (HPLC-EC). Effect of low (1.0mg/kg) dose of apomorphine was found to be non-significant on 5-Hydroxytryptamine (5-HT), 5-Hydroxyindoleacetic acid (5-HIAA) and dopamine (DA) levels. Moderate (2.0 mg/kg) dose of drug increased (p<0.05) levels of Homovanillic acid (HVA). Whereas, high (4.0 mg/kg) dose of apomorphine decreased Dihydroxyphenylacetic acid (DOPAC) levels. Results could be helpful in elucidating the effect of apomorphine at different doses and its implication for extending therapeutics in Parkinson's and related disorders.