Simultaneous determination of 3,4-dihydroxyphenylalanine, 5-hydroxytryptophan, dopamine, 4-hydroxy-3-methoxyphenylalanine, norepinephrine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, serotonin, and 5-hydroxyindoleacetic acid in rat cerebrospinal fluid and brain by high-performance liquid chromatography with electrochemical detection

Simultaneous detection of norepinephrine and 5-hydroxytryptophan using poly-alizarin/multi-walled carbon nanotubes-graphene modified carbon fiber microelectrode array sensor

Multi-walled carbon nanotubes, graphene and alizarin polymer composites coated carbon fiber microelectrode array sensor (p-AZ/MWCNT-GR/CFMEA) was constructed and used for the simultaneous detection of norepinephrine (NE) and 5-hydroxytryptophan (5-HT). The morphology and structural characteristics of sensor are characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Its electrochemical behavior has been studied with cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrochemical activity for the oxidation of NE and 5-HT, two well separated oxidation peaks with the peak potential difference of 220 mV are observed on the cyclic voltammogram. NE and 5-HT both show two electrons and two protons electrochemical reaction on the p-AZ/MWCNT-GR/CFMEA. Under the optimized experiment conditions, the linear ranges of the sensor for NE and 5-HT are 0. 08- 8 μM and 0. 1-20 μM with detection limits of 4. 22 nM and 14. 2 nM (S/N = 3), respectively. In addition, the microsensor array show good reproducibility, stability and selectivity for the determination of NE and 5-HT. Finally, the p-AZ/MWCNT-GR/CFMEA is applied to the simultaneous detection of NE and 5-HT in human serum samples and macrophages.

Catecholaminergic Innervation of Periventricular Neurogenic Regions of the Developing Mouse Brain

The major catecholamines—dopamine (DA) and norepinephrine (NE)—are not only involved in synaptic communication but also act as important trophic factors and might ultimately be involved in mammalian brain development. The catecholaminergic innervation of neurogenic regions of the developing brain and its putative relationship to neurogenesis is thus of pivotal interest. We here determined DA and NE innervation around the ventricular/subventricular zone (VZ/SVZ) bordering the whole ventricular system of the developing mouse brain from embryonic day 14.5 (E14.5), E16.5, and E19.5 until postnatal day zero (P0) by histological evaluation and HPLC with electrochemical detection. We correlated these data with the proliferation capacity of the respective regions by quantification of MCM2⁺ cells. During development, VZ/SVZ catecholamine levels dramatically increased between E16.5 and P0 with DA levels increasing in forebrain VZ/SVZ bordering the lateral ventricles and NE levels raising in midbrain/hindbrain VZ/SVZ bordering the third ventricle, the aqueduct, and the fourth ventricle. Conversely, proliferating MCM2⁺ cell counts dropped between E16.5 and E19.5 with a special focus on all VZ/SVZs outside the lateral ventricles. We detected an inverse strong negative correlation of the proliferation capacity in the periventricular neurogenic regions (log-transformed MCM2⁺ cell counts) with their NE levels (r = −0.932; p < 0.001), but not their DA levels (r = 0.440; p = 0.051) suggesting putative inhibitory effects of NE on cell proliferation within the periventricular regions during mouse brain development. Our data provide the first framework for further demandable studies on the functional importance of catecholamines, particularly NE, in regulating neural stem/progenitor cell proliferation and differentiation during mammalian brain development.

Norepinephrine is a negative regulator of the adult periventricular neural stem cell niche

The limited proliferative capacity of neuroprogenitor cells (NPCs) within the periventricular germinal niches (PGNs) located caudal of the subventricular zone (SVZ) of the lateral ventricles together with their high proliferation capacity after isolation strongly implicates cell-extrinsic humoral factors restricting NPC proliferation in the hypothalamic and midbrain PGNs. We comparatively examined the effects of norepinephrine (NE) as an endogenous candidate regulator of PGN neurogenesis in the SVZ as well as the periventricular hypothalamus and the periaqueductal midbrain. Histological and neurochemical analyses revealed that the pattern of NE innervation of the adult PGNs is inversely associated with their in vivo NPC proliferation capacity with low NE levels coupled to high NPC proliferation in the SVZ but high NE levels coupled to low NPC proliferation in hypothalamic and midbrain PGNs. Intraventricular infusion of NE decreased NPC proliferation and neurogenesis in the SVZ-olfactory bulb system, while pharmacological NE inhibition increased NPC proliferation and early neurogenesis events in the caudal PGNs. Neurotoxic ablation of NE neurons using the Dsp4-fluoxetine protocol confirmed its inhibitory effects on NPC proliferation. Contrarily, NE depletion largely impairs NPC proliferation within the hippocampus in the same animals. Our data indicate that norepinephrine has opposite effects on the two fundamental neurogenic niches of the adult brain with norepinephrine being a negative regulator of adult periventricular neurogenesis. This knowledge might ultimately lead to new therapeutic approaches to influence neurogenesis in hypothalamus-related metabolic diseases or to stimulate endogenous regenerative potential in neurodegenerative processes such as Parkinson's disease.

Single-Shot Detection of Neurotransmitters in Whole-Blood Samples by Means of the Heat-Transfer Method in Combination with Synthetic Receptors

Serotonin is an important neurotransmitter that plays a major role in the pathogenesis of a variety of conditions, including psychiatric disorders. The detection of serotonin typically relies on high-performance liquid chromatography (HPLC), an expensive technique that requires sophisticated equipment and trained personnel, and is not suitable for point-of-care applications. In this contribution, we introduce a novel sensor platform that can measure spiked neurotransmitter concentrations in whole blood samples in a fast and low-cost manner by combining synthetic receptors with a thermal readout technique—the heat-transfer method. In addition, the design of a miniaturized version of the sensing platform is presented that aims to bridge the gap between measurements in a laboratory setting and point-of-care measurements. This fully automated and integrated, user-friendly design features a capillary pumping unit that is compatible with point-of-care sampling techniques such as a blood lancet device (sample volume—between 50 µL and 300 µL). Sample pre-treatment is limited to the addition of an anti-coagulant. With this fully integrated setup, it is possible to successfully discriminate serotonin from a competitor neurotransmitter (histamine) in whole blood samples. This is the first demonstration of a point-of-care ready device based on synthetic receptors for the screening of neurotransmitters in complex matrices, illustrating the sensor’s potential application in clinical research and diagnosis of e.g., early stage depression.

Role of Scoparia dulcis linn on noise-induced nitric oxide synthase (NOS) expression and neurotransmitter assessment on motor function in Wistar albino rats

Noise pollution is one of the most widespread and fast growing environmental and occupational menaces in the modern era. Exposure to noise above 100dB is not adaptable through the brain homeostatic mechanism. Yet, the detrimental effects of noise have often been ignored. Developing reliable animal models to understand the neurobiology of noise stress and advance our research in the field of medicine to impede this growing stressor is needed. In this study experimental animals were divided into four groups, (i) Control and (ii) S. dulcis extract (200mg/kgbw) treated control group. (iii) To mimic the influence of noise, animals in this group were exposed to noise stress (100dB/4h/day) for 15days and finally, (iv) Noise exposed treated with S. dulcis extract (200mg/kgbw) group. Rota-rod and narrow beam performance results showed impaired motor co-ordination in noise exposed group on both 1st and 15th day when compared to controls. This impaired motor function on exposure to noise could be attributed to the altered norepinephrine, dopamine and serotonin levels in both the striatum and cerebellum. Moreover, the motor impaired associated changes could also be attributed to upregulated nNOS and iNOS protein expression in the cerebellum resulting in increased nitric oxide radical production. This increased reactive free radicals species can initiate lipid peroxidation mediated changes in the cerebellar Purkinje cells, which is responsible for initiating inhibitory motor response and ultimately leading to impaired motor co-ordination. Treatment with S. dulcis extract (200mg/kgbw) could control motor impairment and regulate neurotransmitter level as that of control groups when compared to noise exposed group. One key aspect of therapeutic efficacy of the plant could have resulted due to attenuated lipid peroxidation mediated damages on the cerebellar Purkinje cells thereby regulating motor impairment. Thus, targeting the antioxidant and free radicals scavenging properties of the plant could serve as a potential therapeutic to combat this environmental stressor.

Expression profile of neuro-endocrine-immune network in rats with vascular endothelial dysfunction

This study was to determine the correlation between endothelial function and neuro-endocrine-immune (NEI) network through observing the changes of NEI network under the different endothelial dysfunction models. Three endothelial dysfunction models were established in male Wistar rats after exposure to homocysteine (Hcy), high fat diet (HFD) and Hcy+HFD. The results showed that there was endothelial dysfunction in all three models with varying degrees. However, the expression of NEI network was totally different. Interestingly, treatment with simvastatin was able to improve vascular endothelial function and restored the imbalance of the NEI network, observed in the Hcy+HFD group. The results indicated that NEI network may have a strong association with endothelial function, and this relationship can be used to distinguish different risk factors and evaluate drug effects.

Seasonal changes in the activity of the adrenal medulla of Viscacha (Lagostomus maximus maximus)

Animals living in nontropical climates modify their physiology and behavior to adapt to seasonal environmental changes. Part of this adaptation involves the release of catecholamine from sympathetic nerve endings and the adrenal medulla, which play a major role in regulating energy balance. The aim of this work was to investigate whether adult male viscachas in their natural habitat exhibits structural changes in the adrenal medulla during the annual seasonal cycle. In August-September, chromaffin granules revealed ultrastructural changes suggestive of piecemeal degranulation. Quantitative morphometric analysis by transmission electron microscopy showed a significantly lower percentage of resting chromaffin granules and a higher percentage of altered granules and empty containers in August-September (late winter) compared to February-March (late summer), suggesting an increased secretory process of catecholamines in August-September. The mechanism of piecemeal degranulation might amplify this process, encouraging the adaptive response to winter environmental conditions. Tissue levels of epinephrine, norepinephrine, and dopamine (analyzed by high-performance liquid chromatography) changed throughout the year, reaching maximum values in February-March and minimum values in August-September. These results demonstrate morphological and biochemical seasonal variations of the adrenal medulla, suggesting that epinephrine might promote energy mobilization, which allow the Lagostomus to cope with adverse environmental conditions and thus to survive during winter season.

Possible involvement of supersensitivity in cerebral ?-adrenergic and dopaminergic receptors in the occurrence of sensitization to d-methamphetamine in mice

Behavioral sensitization of mice (male STD-ddy) to d-methamphetamine (MAP) and its correlation with the neurochemical alterations in cerebral catecholaminergic systems were investigated following the repeated administration of MAP (5 mg/kg, i.p. x 2/day, 5 days). MAP-pretreated mice showed an enhancement in MAP-stimulated locomotor activity following the readministration of MAP (0.625 mg/kg). The metabolic turnovers of cerebral norepinephrine (NE) and dopamine (DA) showed a significant decrease in these sensitized mice. The activities of tyrosine hydroxylase. DOPA decarboxylase, monoamine oxidase and catechol-O-methyltransferase, however, showed no change under the same experimental conditions. On the other hand, the repeated MAP pretreatment induced the enhancement of the specific bindings of [(3)H]dihydroalprenolol and [(3)H]spiperone to cerebral synaptic membrane, which resulted from the increase of B(max) values. Furthermore, pretreatments of mice with propranolol (10 mg/kg) and haloperidol (0.1 mg/kg) inhibited the development of behavioral sensitization to MAP. These results suggest that the supersensitivity in cerebral ?-adrenergic and dopaminergic receptors may be involved in behavioral sensitization to MAP.

Chromatographic assay to study the activity of multiple enzymes involved in the synthesis and metabolism of dopamine and serotonin

Serotonin and dopamine are crucial regulators of signalling in the peripheral and central nervous systems. We present an ex-vivo, isocratic chromatographic method that allows for the measurement of tyrosine, L-3,4-dihydroxyphenylalanine (L-DOPA), dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), tryptophan, 5-hydroxytryptophan (5-HTP), serotonin and 5-hydroxy-3-indoleacetic acid (5-HIAA) in a model central nervous (CNS) system, to study the role of key enzymes involved in the synthesis and metabolism of serotonin and dopamine. By utilising a sample splitting technique, we could test a single CNS sample at multiple time points under various pharmacological treatments. In, addition, we were able to conduct this assay by utilising the endogenous biochemical components of the CNS to study the synthesis and metabolism of serotonin and dopamine, negating the requirement of additional enzyme activators or stabilisers in the biological matrix. Finally we utilised NSD-1015, an aromatic amino acid decarboxylase enzyme inhibitor used to study the synthesis of dopamine and serotonin to monitor alterations in levels of key neurochemicals. 3-hydroxybenzylhydrazine dihydrochloride (NSD-1015) was able to reduce levels of serotonin and dopamine, whilst elevating precursors L-DOPA and 5-HTP.

Influence of Momordica charantia on oxidative stress-induced perturbations in brain monoamines and plasma corticosterone in albino rats

Objectives:

The objective of this study was to evaluate the antistress activity of Momordica charantia (MC) fruit extract on stress-induced changes in albino rats and also to explore attenuating effects of MC on in vitro lipid peroxidation in rat brain.

Materials and Methods:

In this study, Wistar albino rats (180–200 g) were used. Plasma corticosterone and monoamines—5-hydroxy tryptamine (5-HT), norepinephrine (NE), epinephrine (E) and dopamine (DA) in cortex, hypothalamus and hippocampus regions of brain were determined in animals under different stressful conditions. Ethanolic fruit extract of MC, at doses of 200 and 400 mg/kg, was used. The oxidative stress paradigms used in in vivo models were acute stress (AS) and chronic unpredictable stress (CUS). Panax quinquefolium (PQ) was used as a standard in in vivo models and ascorbic acid was used as a reference standard in the in vitro method.

Results:

Subjecting the animals to AS (immobilization for 150 min once only) resulted in significant elevation of plasma corticosterone levels and brain monoamine levels. Pretreatment with MC at doses of 200 and 400 mg/kg p.o. significantly countered AS-induced changes and a similar effect was exhibited by PQ at 100 mg/kg p.o. In the CUS regimen (different stressors for 7 days), plasma corticosterone levels were significantly elevated whereas the levels of 5-HT, NE, E, and DA were depleted significantly. Pretreatment with MC (200 and 400 mg/kg) attenuated the CUS-induced changes in the levels of above monoamines in cortex, hypothalamus, and hippocampus regions of brain and plasma corticosterone in a dose-dependent manner. Furthermore, MC extract (1000–5000 μg/mL) exhibited a significant quenching effect on in vitro lipid peroxidation indicating its strong antioxidant activity which was compared with ascorbic acid.

Conclusions:

This study reveals the antistress activity of MC as it significantly reverted the stress-induced changes, and the activity might be attributed to its antioxidant activity since stress is known to involve several oxidative mechanisms.

Dual beneficial effects of (-)-epigallocatechin-3-gallate on levodopa methylation and hippocampal neurodegeneration: in vitro and in vivo studies

BACKGROUND

A combination of levodopa (L-DOPA) and carbidopa is the most commonly-used treatment for symptom management in Parkinson's disease. Studies have shown that concomitant use of a COMT inhibitor is highly beneficial in controlling the wearing-off phenomenon by improving L-DOPA bioavailability as well as brain entry. The present study sought to determine whether (-)-epigallocatechin-3-gallate (EGCG), a common tea polyphenol, can serve as a naturally-occurring COMT inhibitor that also possesses neuroprotective actions.

METHODOLOGY/PRINCIPAL FINDINGS

Using both in vitro and in vivo models, we investigated the modulating effects of EGCG on L-DOPA methylation as well as on chemically induced oxidative neuronal damage and degeneration. EGCG strongly inhibited human liver COMT-mediated O-methylation of L-DOPA in a concentration-dependent manner in vitro, with an average IC50 of 0.36 microM. Oral administration of EGCG moderately lowered the accumulation of 3-O-methyldopa in the plasma and striatum of rats treated with L-DOPA+carbidopa. In addition, EGCG also reduced glutamate-induced oxidative cytotoxicity in cultured HT22 mouse hippocampal neuronal cells through inactivation of the nuclear factor kappaB-signaling pathway. Under in vivo conditions, administration of EGCG exerted a strong protective effect against kainic acid-induced oxidative neuronal death in the hippocampus of rats.

CONCLUSIONS/SIGNIFICANCE

These observations suggest that oral administration of EGCG may have significant beneficial effects in Parkinson's patients treated with L-DOPA and carbidopa by exerting a modest inhibition of L-DOPA methylation plus a strong neuroprotection against oxidative damage and degeneration.

Ontogenetic exposure of rats to pre- and post-natal manganese enhances behavioral impairments produced by perinatal 6-hydroxydopamine

Rats lesioned shortly after birth with 6-hydroxydopamine (6-OHDA; 134 μg icv) represent a near-ideal model of severe Parkinson's disease because of the near-total destruction of nigrostriatal dopaminergic fibers. The element manganese, an essential cofactor for many enzymatic reactions, itself in toxic amount, replicates some clinical features similar to those of Parkinson's disease. The aim of this study was to examine the effect of neonatal manganese exposure on 6-OHDA modeling of Parkinson's disease in rats. Manganese (MnCl(2)·4H(2)O) 10,000 ppm was included in the drinking water of pregnant Wistar rats from the time of conception until the 21st day after delivery, the age when neonatal rats were weaned. Control rats consumed tap water. Other groups of neonatal rat pups, on the 3rd day after birth, were pretreated with desipramine (20 mg/kg ip 1 h) prior to bilateral icv administration of 6-OHDA (30, 60, or 137 μg) or its vehicle saline-ascorbic (0.1%) (control). At 2 months after birth, in rats lesioned with 30, 60, or 134 μg 6-OHDA, endogenous striatal dopamine (DA) content was reduced, respectively, by 66, 92, and 98% (HPLC/ED), while co-exposure of these groups to perinatal manganese did not magnify the DA depletion. However, there was prominent enhancement of DA D(1) agonist (i.e., SKF 38393)-induced oral activity in the group of rats exposed perinatally to manganese and also treated neonatally with the 30 mg/kg dose of 6-OHDA. The 30 mg/kg 6-OHDA group, demonstrating cataleptogenic responses to SCH 23390 (0.5 mg/kg) and haloperidol (0.5 mg/kg ip), developed resistance if co-exposed to perinatal manganese. In the group exposed to manganese and lesioned with the 60 mg/kg dose of 6-OHDA, there was a reduction in D(2) agonist (i.e., quinpirole, 0.1 mg/kg)-induced yawning. The series of findings demonstrate that ontogenetic exposure to manganese results in an enhancement of behavioral toxicity to a moderate dose of 6-OHDA, despite the fact that there is no enhanced depletion of striatal DA depletion by the manganese treatment.

Central levodopa influx and the clinical motor response to levodopa in patients with Parkinson disease complicated with motor fluctuations and dyskinesias

OBJECTIVE

To study the possible relationship between central levodopa influx and short-term antiparkinsonian and dyskinetic responses to levodopa in patients with Parkinson disease.

METHODS

The clinical response to a single oral dose of standard and controlled-release levodopa/carbidopa was assessed in 12 patients with Parkinson disease complicated with motor fluctuations and dyskinesias. Plasma concentrations of levodopa and large neutral amino acids were determined, and the theoretical central levodopa influx was calculated using a model based on competitive inhibition of substrates to cross the blood-brain barrier.

RESULTS

The mean (SD) central levodopa influxes at the onset of the antiparkinsonian clinical effect were 19.7 (10.9 x 10(-3) and 19.1 (7.4 x 10(-3) nmol min(-1) g(-)1 (P >0.1) for standard and controlled-release levodopa, respectively. The mean (SD) central levodopa influxes at the onset of choreic dyskinesias were 20.1 (8.2 x 10 (-3) and 19.9 (10.8 x 10(-3) nmol min (-1) g(-)1 (P 9 0.1) for standard and controlled-release levodopa, respectively. During the tests, choreic dyskinesias were associated with a central levodopa influx of 10 x 10(-3) nmol min(-1) g(-1) or greater, and foot dystonia occurred with a central levodopa influx less than 9 x 10(-3) nmol min(-1) g(-1).

CONCLUSIONS

The clinical response to levodopa in patients with advanced Parkinson disease may be related to central levodopa influx. We found no differences in the central levodopa influx threshold for clinical improvement with different levodopa formulations. The central levodopa influxes at the onset of choreic dyskinesias and antiparkinsonian effect were similar. Choreic dyskinesias and foot dystonia were associated with high and low central levodopa influx, respectively.

Synthesis and application of a peroxidase-like molecularly imprinted polymer based on hemin for selective determination of serotonin in blood serum

This work reports the preparation of a molecularly imprinted polymer (MIP) for selective catalytic detection of serotonin (5-hydroxytryptamine, 5-HT). The process is based on the synthesis of polymers with hemin introduced as the catalytic center to mimic the active site of peroxidase. The copolymer MIP, containing artificial recognition sites for 5-HT, has been prepared by bulk polymerization using methacrylic acid (MAA) and hemin as the functional monomers, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. For the determination of 5-HT, a flow injection analysis system coupled to an amperometric detector was optimized using multivariate analysis. The effects of different parameters, such as pH, buffer flow rate, buffer nature, peroxide concentration and sample volume were evaluated. After optimizing the experimental conditions, a linear response range from 1.0 up to 1000.0 micromolL(-1) was obtained with a sensitivity of 0.4nA/ micromolL(-1). The detection limit was found to be 0.30 micromolL(-1), while the precision values (n=6) evaluated by relative standard deviation (R.S.D.) were, respectively, 1.3 and 1.7% for solutions of 50 and 750 micromolL(-1) of 5-HT. No interference was observed by structurally similar compounds (including epinephrine, dopamine and norepinephrine), thus validating the good performance of the imprinted polymer. The method was applied for the determination of 5-HT in spiked blood serum samples.

Effect of prenatal lead exposure on nigrostriatal neurotransmission and hydroxyl radical formation in rat neostriatum: dopaminergic-nitrergic interaction

The present study was designed to explore the role of ontogenetic lead (Pb(2+)) exposure on a putative dopaminergic-nitrergic interaction in the nigrostriatal pathway. Pregnant Wistar rats were given tap water containing 250-ppm lead acetate, for the duration of pregnancy, with regular tap water (without Pb(2+)) being substituted at birth. Control rats were derived from dams that consumed tap water throughout pregnancy, and had no exposure to Pb(2+) afterwards. At 12 weeks after birth in vivo microdialysis of the neostriatum was employed to demonstrate that maternal Pb(2+) exposure was without effect on the baseline dopamine (DA) microdialysate concentration as well as amphetamine (AMPH, 1.0mg/kg i.p.)-evoked release of striatal DA. Also, prenatal Pb(2+) exposure did not enhance AMPH- and 7-nitroindazole (neuronal nitric oxide synthase inhibitor) (7-NI, 20mg/kg i.p.)-induced hydroxyl radical (HO) formation in the striatum, as indicated by analysis of the salicylate spin-trap product 2,5-dihydroxybenzoic acid. However, in rats exposed prenatally to Pb(2+), the facilitatory effect of 7-NI on DA exocytosis was attenuated. On the basis of the current study we conclude that maternal Pb(2+) exposure distorts the dopaminergic-nitrergic interaction in the nigrostriatal pathway, but without involvement of reactive oxygen species (ROS).

Dexamethasone reduces food intake, weight gain and the hypothalamic 5-HT concentration and increases plasma leptin in rats

This study was conducted to define the regulatory mechanisms underlying stress-induced decreases in food intake and weight gain. Rats received a single or 4 daily injections of dexamethasone (0.1 or 1 mg/kg). Food intake and weight gain were recorded, and plasma leptin, brain contents of serotonin (5-hydroxytryptamine; 5-HT), 5-hydroxy-indole-acetic acid (5-HIAA) and the raphe expression of tryptophan hydroxylase (TPH), monoamine oxidase A (MAO-A) and 5-HT reuptake transporter (5-HTT) genes were examined. A single injection of dexamethasone did not acutely affect food intake, but cumulative food intake and weight gain were suppressed dose-dependently by daily injections of dexamethasone. Both a single and repeated injections of dexamethasone elevated plasma leptin in a dose dependent manner. 5-HT contents in the hypothalamus was decreased, but 5-HIAA increased, both by a single and repeated dexamethasone. A single injection of dexamethasone did not affect mRNA expressions of TPH, MAO-A and 5-HTT genes, but repeated dexamethasone increased them in the dorsal raphe nucleus. These results suggest that plasma leptin may play a role in dexamethasone-induced anorexia. Additionally, increased expression of MAO-A and 5-HTT genes by repeated dexamethasone appears to be implicated in decreases of the brain 5-HT contents.

Amphetamine and mCPP effects on dopamine and serotonin striatal in vivo microdialysates in an animal model of hyperactivity

In the neonatally 6-hydroxydopamine (6-OHDA)-lesioned rat hyperlocomotor activity, first described in the 1970s, was subsequently found to be increased by an additional lesion with 5,7-dihydroxytryptamine (5,7-DHT) (i.c.v.) in adulthood. The latter animal model (i.e., 134 microg 6-OHDA at 3 d postbirth plus 71 microg 5,7-DHT at 10 weeks; desipramine pretreatments) was used in this study, in an attempt to attribute hyperlocomotor attenuation by D,L-amphetamine sulfate (AMPH) and m-chlorophenylpiperazine di HCl (mCPP), to specific changes in extraneuronal (i.e., in vivo microdialysate) levels of dopamine (DA) and/or serotonin (5-HT). Despite the 98-99% reduction in striatal tissue content of DA, the baseline striatal microdialysate level of DA was reduced by 50% or less at 14 weeks, versus the intact control group. When challenged with AMPH (0.5 mg/kg), the microdialysate level of DA went either unchanged or was slightly reduced over the next 180 min (i.e., 20 min sampling), while in the vehicle group and 5,7-DHT (alone) lesioned group, the microdialysate level was maximally elevated by approximately 225% and approximately 450%, respectively--and over a span of nearly 2 h. Acute challenge with mCPP (1 mg/kg salt form) had little effect on microdialysate levels of DA, DOPAC and 5-HT. Moreover, there was no consistent change in the microdialysate levels of DA, DOPAC, and 5-HT between intact, 5-HT-lesioned rats, and DA-lesioned rats which might reasonably account for an attenuation of hyperlocomotor activity. These findings indicate that there are other important neurochemical changes produced by AMPH- and mCPP-attenuated hyperlocomotor activity, or perhaps a different brain region or multiple brain regional effects are involved in AMPH and mCPP behavioral actions.

Maternal lead exposure produces long-term enhancement of dopaminergic reactivity in rat offspring

To determine the effect of prenatal lead exposure on brain monoaminergic systems, pregnant rats were given tap water containing 250 ppm lead acetate, for the duration of pregnancy, while tap water without lead (Pb(2+)) was substituted at birth. Control rats were derived from dams that consumed tap water during pregnancy, and had no exposure to lead afterwards. At 12 weeks after birth, Pb(2+) content of brain cortex was increased 3- to 4-fold (P < 0.05). At this time the endogenous striatal levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid were 19% lower in Pb(2+) exposed rats (P < 0.05), while there was no change in the striatal level of dopamine (DA), noradrenaline, 3,4-dihydroxyphenylglycol, serotonin (5-HT) and 5-hydroxyindoleacetic acid (HPLC/ED). Also there was no change in these monoamines and metabolites in the prefrontal cortex of Pb(2+) exposed rats. However, turnover of 5-HT in prefrontal cortex, as indicated by 5-hydroxytryptophan accumulation 30 min after acute treatment with the decarboxylase inhibitor NSD-1015 (100 mg/kg IP), was lower in the Pb(2+) exposed rats. In the striatum AMPH-induced (1 mg/kg IP) turnover of DA, evidenced as L-DOPA accumulation after NSD-1015, was increased to a lesser extent in the Pb(2+) exposed rats (P < 0.05). The nitric oxide synthase inhibitor 7-nitroindazole (10 mg/kg IP) attenuated the latter effect, indicating that neuronal NO mediates this AMPH effect, at least in part. Moreover, DA D(2) receptor sensitivity developed in Pb(2+) exposed rats, as evidenced by enhanced quinpirole-induced yawning activity and enhanced quinpirole-induced locomotor activity (each, P < 0.05). These findings indicate that ontogenetic exposure to lead can have consequences on monoaminergic neuronal function at an adult stage of life, generally promoting accentuated behavioral effects of direct and indirect monoaminergic agonists, and related to increased dopamine turnover in basal ganglia.

Chronic food restriction in young rats results in depression- and anxiety-like behaviors with decreased expression of serotonin reuptake transporter

Evidence of semi-starvation is commonly found in patients with eating disorders. This study was conducted to examine the adverse effects of chronic caloric restriction in young rats, since there have been increasing incidence of eating disorders especially among young populations. Food restriction group was supplied daily with 50% of chow consumed by its ad libitum fed control group from postnatal day 28. After 5 weeks of food restriction, brain contents of serotonin (5-hydroxy-tryptamine; 5-HT) and its metabolite 5-hydroxyindol acetic acid were analyzed by high-performance liquid chromatography and mRNA expression of 5-HT reuptake transporter (5-HTT) by in situ hybridization. Plasma corticosterone levels were determined by radioimmunoassay. Behavioral assessments were performed with Porsolt swim test for depressive behavior and with elevated plus maze test for anxiety. Five weeks of food restriction markedly increased plasma level of corticosterone, and significantly decreased 5-HT turnover rates in the hippocampus and the hypothalamus. 5-HTT mRNA expression decreased in the raphe nucleus of food restricted rats compared with free fed controls. Immobility time during the swim test increased in the food restricted group, compared to the control group. Food restricted rats spent more time in the closed arms, less time in the open arms, of elevated plus maze compared with control rats. These results suggest that chronic caloric restriction in young rats may lead to the development of depressive and/or anxiety disorders, likely, in relation with dysfunction of brain 5-HT system.

Depressive behaviors and decreased expression of serotonin reuptake transporter in rats that experienced neonatal maternal separation

This study was conducted to examine the pathophysiologic mechanisms of long-term adverse effects by neonatal maternal separation on neurobehaviors of the offspring. Sprague-Dawley pups were separated from dam daily for 180min during the first 2 weeks of life (MS) or undisturbed (NH), and subjected to behavioral sessions for ambulatory activity, forced swim, and elevated plus maze tests at 2 months of age. Serotonin reuptake transporter (5-HTT) mRNA levels in the raphe nucleus and the contents of serotonin (5-HT) and its metabolite 5-hydroxyindol acetic acid in the raphe and the hippocampus were examined as well. Ambulatory counts decreased and immobility duration in swim test increased in MS rats compared with NH rats. MS rats spent more time in the closed arms, less time in the open arms, of elevated plus maze, compared to NH rats. The hippocampal contents of 5-HT and the raphe expression of 5-HTT mRNA were decreased in MS rats compared with NH rats. These results suggest that neonatal maternal separation may result in the development of depression- and/or anxiety-like behaviors in later life, in which the long-term alterations in 5-HTergic neurotransmission may take a role.

In vivo induction of heat shock proteins in the substantia nigra following L-DOPA administration is associated with increased activity of mitochondrial complex I and nitrosative stress in rats: regulation by glutathione redox state

Increasing evidence suggests a critical role for oxidative and nitrosative stress in the pathogenesis of most important neurodegenerative disorders. Parkinson's disease (PD) is a neurodegenerative disease characterized by a severe depletion in number of dopaminergic cells of the substantia nigra (SN). Administration of L-DOPA (LD) is the more effective treatment for patients with PD. However, the vast majority of patients suffer LD-related complications, which represent the major problem in the clinical management of PD. In the present study, LD administration to rats resulted in a significant dose-dependent increase in Hsp70 synthesis which was specific for the SN. The amount of 70 kDa protein increased after 6 h treatment reaching the maximal induction after 24-48 h. Induction of Hsp70 in the SN was associated with a significant increase in constitutive Hsc70 and mitochondrial Hsp60 stress proteins, and with increased expression of mitochondrial complex I whereas no significant changes were found in the activity of complex IV. In the same experimental conditions, a significant decrease in reduced glutathione was observed, which was associated with an increased content of oxidized glutathione content as well as nitric oxide (NO) synthase activity, NO metabolites and nitrotyrosine immunoreactivity. Interestingly, Hsp70 induction, iNOS up-regulation and nitrotyrosine formation have been confirmed also in SN and striatum of rats treated with LD and carbidopa, this latter being an inhibitor of the peripheral DOPA decarboxylase. Our data are in favor of the importance of the heat shock signal pathway as a basic mechanism of defense against neurotoxicity elicited by free radical oxygen and nitrogen species produced in aging and neurodegenerative disorders.

Stress response in rat brain after different durations of noise exposure

The alteration in the levels of plasma corticosterone, brain norepinephrine (NE), and expression of brain heat shock proteins (Hsp70) after different durations of noise exposure (acute, 1 day; sub-acute, 15 days; chronic, 30 days) has been studied to analyze their role in combating time-dependent stress effects of noise. Broadband white noise (100dB) exposure to male Wistar albino rats significantly increased the levels of plasma corticosterone and NE in all three durations of noise exposure. The sustained increase observed in their levels in the chronic group suggests that animals are not getting adapted to noise even after 30 days of exposure. The important role of Hsp70 in combating noise induced stress is evident from the significant increase in its expression after chronic exposure, while there was a reciprocal decrease in the NE and corticosterone when compared with their levels after acute and sub-acute noise exposure. This clearly indicates that the time-dependent stress response to noise exposure is a complex mechanism involving highly interconnected systems such as hypothalamo-pituitary-adrenal (HPA) axis, heat shock proteins and may have serious implications in vital organs, particularly in the brain when there is a prolonged noise exposure.

In vivo complementation of complex I by the yeast Ndi1 enzyme. Possible application for treatment of Parkinson disease

Recent studies suggest that dysfunction of the NADH-quinone oxidoreductase (complex I) is associated with a number of human diseases, including neurodegenerative disorders such as Parkinson disease. We have shown previously that the single subunit rotenone-insensitive NADH-quinone oxidoreductase (Ndi1) of Saccharomyces cerevisiae mitochondria can restore NADH oxidation in complex I-deficient mammalian cells. The Ndi1 enzyme is insensitive to complex I inhibitors such as rotenone and 1-methyl-4-phenylpyridinium ion, known as a metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). To test the possible use of the NDI1 gene as a therapeutic agent in vivo, we chose a mouse model of Parkinson disease. The NDI1-recombinant adeno-associated virus particles (rAAV-NDI1) were injected unilaterally into the substantia nigra of mice. The animals were then subjected to treatment with MPTP. The degree of neurodegeneration in the nigrostriatal system was assessed immunohistochemically through the analysis of tyrosine hydroxylase and glial fibrillary acidic protein. It was evident that the substantia nigra neurons on the side used for injection of rAAV-NDI1 retained a high level of tyrosine hydroxylase-positive cells, and the ipsilateral striatum exhibited significantly less denervation than the contralateral striatum. Furthermore, striatal concentrations of dopamine and its metabolites in the hemisphere that received rAAV-NDI1 were substantially higher than those of the untreated hemisphere, reaching more than 50% of the normal levels. These results indicate that the expressed Ndi1 protein elicits resistance to MPTP-induced neuronal injury. The present study is the first successful demonstration of complementation of complex I by the Ndi1 enzyme in animals.

Biogenic amine changes in brain regions and attenuating action of Ocimum sanctumin noise exposure

Broadband white noise exposure (100 dB) in wistar strain male albino rats significantly increased the levels of dopamine (DA), serotonin (5-HT) and 5-HT turnover in many of the discrete brain regions (cerebral cortex, cerebellum, hypothalamus, hippocampus, pons-medulla and corpus striatum) during sub-chronic noise exposure (4 h daily for 15 days). In acute (4 h for 1 day) and chronic noise exposures (4 h daily for 30 days) the levels were significantly altered only in certain regions. The turnover study of serotonin clearly indicates that neurotransmitter level alone cannot be an indicator, as in some brain regions the rate of synthesis matched with the degradation in order to maintain the normal levels. The intraperitoneal administration of 70% ethanolic extract of Ocimum sanctum(OS) at the dosage of 100 mg/kg body weight to animals subjected to noise exposure has prevented the noise induced increase in neurotransmitter levels without affecting the normal levels. This indicates that OS can be a probable herbal remedy for noise induced biogenic amine alterations.

Brain aging phenomena in migrating sockeye salmon Oncorhynchus nerka nerka

Aging, a process occurring in all vertebrates, is closely related to a loss in physical and functional abilities. There is widespread interest in clarifying the relevance of environmental, metabolic, and genetic factors for vertebrate aging. In the Pacific salmon a dramatic example of aging is known. Looking for changes in the salmon brain, perhaps even in the role of initiating the aging processes, we investigated several biochemical parameters that should reflect brain functional activity and stress response such as the neurotransmitters dopamine, and serotonin, and two of their respective metabolites 3,4-dihydroxyphenylacetic acid, and 5-hydroxyindole acetic acid, as well as glutathione, glutathione disulfide, and the extent of terminal deoxynucleotidyltransferase-mediated dUTP nick end-labelling. The aging of migrating sockeye salmon (Oncorhynchus nerka nerka) is accompanied by gradual increase in dopamine and serotonin turnover and a gradual decrease of brain total protein and glutathione levels. There appears to be an increased need for detoxification of reactive biological intermediates since activities of superoxide dismutase and catalase increase with age. However, our data do not support a major increase in apoptotic cell death during late aging but rather implicate an age related downward regulation of protein and glutathione synthesis and proteolysis increasing the need for autophagocytosis or heterophagocytosis in the course of cell death.

Noise-Stress-Induced Brain Neurotransmitter Changes and the Effect of Ocimum sanctum (Linn) Treatment in Albino Rats

In this modern world, stress and pollution are unavoidable phenomena affecting the body system at various levels. A large number of people are exposed to potentially hazardous noise levels in daily modern life, such as noise from work environments, urban traffic, and household appliances. A variety of studies have suggested an association between noise exposure and the occurrence of disorders involving extra-auditory organs such as disorders of the nervous, endocrine, and cardiovascular systems. In this study, Wistar strain albino rats were subjected to 100 dB broadband white noise, 4 h daily for 15 days. The high-pressure liquid chromatographic estimation of norepinephrine, epinephrine, dopamine, and serotonin in discrete regions of the rat brain indicates that noise stress can alter the brain biogenic amines after 15 days of stress exposure. Ocimum sanctum (OS), a medicinal herb that is widely claimed to posses antistressor activity and used extensively in the Indian system of medicine for a variety of disorders, was chosen for this study. Administration of the 70% ethanolic extract of OS had a normalizing action on discrete regions of brain and controlled the alteration in neurotransmitter levels due to noise stress, emphasizing the antistressor potential of this plant.

The effect of venlafaxine on behaviour, body weight and striatal monoamine levels on sleep-deprived female rats

Partial sleep deprivation is clinically associated with fatigue, depressive symptoms and reduced memory. Previously, it has been demonstrated that venlafaxine, an atypical antidepressant, increases the levels of noradrenaline and serotonin in rat hippocampus. The aim of this study was to evaluate the effects of venlafaxine on depression, anxiety, locomotor activity and memory in a model of REM sleep (REMs) deprivation in rats. We have also studied the influence of venlafaxine on monoamine levels in the striatum. Six groups of animals (N=20 each) were treated with saline or venlafaxine (1 or 10 mg/kg) during 10 days, submitted or not to REMs deprivation and studied with the forced swimming test of Porsolt (STP), plus-maze, passive avoidance and open-field tests right after sleep deprivation. Animals were also studied for passive avoidance 24 h later (rebound period). Brain samples for monoamine measurements were collected either immediately after REMs deprivation or after 24 h. Both REMs deprivation and venlafaxine showed an antidepressant effect. An anxiolytic effect was also observed after REMs deprivation. Previous treatment with venlafaxine blocked the antidepressant and anxiolytic effects of REMs deprivation. REMs deprivation alone and treatment with venlafaxine 10 mg/kg increased locomotor activity, and this effect was inhibited by venlafaxine in REMs deprived rats. Both venlafaxine treatment and REMs deprivation induced weight loss. Venlafaxine treatment, but not REMs deprivation, induced an increase in striatal dopamine (DA) levels. The combination of REMs deprivation and venlafaxine treatment was associated with an increase in serotonin turnover 24 h after rebound sleep. In this study, venlafaxine treatment hindered most behavioral effects of REMs deprivation and was associated with an interference on dopamine and serotonin systems in the striatum.

Protective effect of diltiazem on cyanide-induced neurotoxicity in Wistar strain rats

Cyanide is a well-established poison known for its rapid lethal action and toxicity. The central nervous system is one of the main target sites for cyanide toxicity. Cyanide not only alters brain biogenic amine levels but also the intracellular calcium levels in the neuronal cells. In the present study the role of calcium channel blocker diltiazem (DIL) in cyanide induced biogenic amine changes was evaluated in the Wistar strain rats. The protective effect of diltiazem pretreatment and diltiazem treatment along with cyanide on the dopaminergic system and the serotonergic system in the corpus striatum were studied. Diltiazem pretreatment was found to prevent cyanide induced changes in both the amines in the corpus striatum. These results suggest that diltiazem may mitigate the harmful effects of cyanide by interfering with influx of calcium ions and release of the biogenic amines.

Alternating extremely low frequency magnetic field increases turnover of dopamine and serotonin in rat frontal cortex

The aim of this study was to evaluate the influence of an extremely low frequency sinusoidal magnetic field (ELF MF) with frequency of 10 Hz and intensity of 1.8-3.8 mT on the levels of the biogenic amines dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 3-methoxytyramine (3-MT), 5-hydroxytryptamine (5-HT), 5-hydroxyindolacetic acid (5-HIAA), and noradrenaline (NA), as well as on DA and 5-HT turnover in corpus striatum and frontal cortex of adult male Wistar rats. We found that ELF MF exposure for 14 days, 1 h daily, did not influence the level of the examined biogenic amines and metabolites, but increased the rate of synthesis (turnover) of DA and 5-HT in rat frontal cortex as compared to control, sham exposed rats. On the basis of the present results and our previous findings, extremely low frequency magnetic field (ELF MF) exposure has been found to alter both turnover and receptor reactivity of monoaminergic systems, as well as some behaviors induced by these systems or their agonists and antagonists.

Systemic 5-hydroxy-L-tryptophan down-regulates the arcuate CART mRNA level in rats

This study was conducted to determine if serotonin (5-hydroxytryptamine; 5-HT) system correlates with the hypothalamic expression of cocaine-amphetamine-regulated transcript (CART) gene. Rats received intraperitoneal 5-hydroxy-L-tryptophan (5-HTP; a single or three daily injections at a dose of 100 mg/kg/10 ml), and CART mRNA level in the hypothalamus was examined by in situ hybridization at different time points. The 5-HT contents of the hypothalamus as well as the brainstem was increased persistently by 5-HTP injections, and food intake and body weight gain reduced. CART mRNA level decreased significantly in the hypothalamic arcuate nucleus by three daily 5-HTP, but not by a single injection. The pair-fed group of the chronic 5-HTP did not show a decrease in the arcuate CART mRNA level. The plasma leptin level markedly decreased in the chronic 5-HTP group, compared to the saline group, however, still higher than the pair-fed group with a statistical significance. These results suggest that 5-HT may suppress CART mRNA expression in the arcuate nucleus, not only by leptin signaling via its anorectic effect on the control of food intake, but also by some non-leptin mediated pathway.

Endocrine and lymphoproliferative response changes produced by social stress in mice

Daily dyadic resident-intruder encounters and uninterrupted cohabitation in pairs were used to assess the impact of different durations (5 and 15 days) of dominance and subordination experiences on splenic lymphoproliferative responses in male OF1 strain mice. HPA axis activity was assessed by measuring serum corticosterone levels, whereas splenic norepinephrine (NE) content provided a sympathetic activity index. Corticosterone levels in subordinate subjects were generally higher than in their control or dominant counterparts in both treatment paradigms. Corticosterone levels in dominant subjects were lower than in their control counterparts in both. Increasing the duration of treatments generally decreased such titers, especially so in subordinate subjects. No differences were detected in splenic NE content. Animals subjected to social interaction generally showed greater proliferation than their control counterparts. This effect was more pronounced in subordinates than dominants and after longer- rather than short-duration treatments. There was no inverse relation between proliferative responses and the subject's corticosterone levels. While corticosterone may have a general immunomodulating effect, other mediators apparently account for the effects produced by these social stress paradigms on splenic proliferative response.

Increased methamphetamine-induced locomotor activity and behavioral sensitization in histamine-deficient mice

We have recently suggested that the brain histamine has an inhibitory role on the behavioral effects of methamphetamine by pharmacological studies. In this study, we used the histidine decarboxylase gene knockout mice and measured the spontaneous locomotor activity, the changes of locomotion by single and repeated administrations of methamphetamine, and the contents of brain monoamines and amino acids at 1 h after a single administration of methamphetamine. In the histidine decarboxylase gene knockout mice, spontaneous locomotor activity during the dark period was significantly lower than in the wild-type mice. Interestingly, methamphetamine-induced locomotor hyperactivity and behavioral sensitization were facilitated more in the histidine decarboxylase gene knockout mice. In the neurochemical study, noradrenaline and O-phosphoserine were decreased in the midbrain of the saline-treated histidine decarboxylase gene knockout mice. On the other hand, single administration of methamphetamine decreased GABA content of the midbrain of the wild-type mice, but did not alter that of histidine decarboxylase gene knockout mice. These results suggest that the histamine neuron system plays a role as an awakening amine in concert with the noradrenaline neuron system, whereas it has an inhibitory role on the behavioral effects of methamphetamine through the interaction with the GABAergic neuron system.

Effect of chronic protein restriction on motor co-ordination and brain neurotransmitters in albino rats

In this study we evaluated the motor co-ordination in Wistar strain albino rats that were maintained on a protein-restricted diet for a period of 1 year immediately after the weaning period, by substituting 75% of the normal diet with a carbohydrate-rich diet deficient in protein, for a period of 1 year immediately after the weaning period. This type of chronic protein restriction caused disturbances in motor co-ordination. It also caused a significant reduction in the basal levels of dopamine, norepinephrine, epinephrine and serotonin along with their metabolites homovanillic acid (HVA), vanillyl mandelic acid (VMA) and 5-hydroxy indoleacetic acid (5HIAA) and precursor L-dopa in the corpus striatum and cerebellum. Changes in these neurotransmitters could have caused altered co-ordination in the protein-restricted animals.

Social stress paradigms in male mice: Variations in behavior, stress and immunology

Male OF1 strain mice were allocated, after 2 weeks of individual housing, to cohabitating (6 or 16 days), fixed dyadic interaction pairs (6 or 16 daily encounters) or control groups (6 or 16 days). These different social stress situations were assessed for their effects on splenic contents of NE, IL-1 and IL-2 and serum levels of corticosterone. Spleen NE contents showed no significant variations, but serum corticosterone titers were generally higher in interacting pairs and subordinates. Splenic IL-2 did not respond in the same way to the treatments as IL-1. The differences in splenic interleukin contents could not be simply related to observed changes in serum corticosterone levels. Different mechanisms appear to regulate changes in glucocorticoids and the measured cytokines. These physiological phenomena do not simply reflect in the animal's social status (dominant or submissive). The intensity and duration of the agonistic behavior displayed as well as the interaction experience accumulated may account for the observed differences between the paradigms.

Effect of cassava consumption on open-field behavior and brain neurotransmitters in albino rats

Diet exerts a critical influence on human biology and thus studies on the interrelationship of nutrition and behavior continues to be a major and important focus of research in the natural experimental sciences. Cassava is known to cause metabolic and neurological derangement on long-term consumption as a staple diet in the tropics. In this article we present the effects of cassava consumption on open-field behavior and catecholamine levels in the hypothalamus of albino rats. Cassava consumption for 30 days alters the emotional status of the rats, with changes in the basal neurotransmitter levels in the hypothalamus. The role of the cyanide (liberated from cassava) and protein deficiency (associated with cassava consumption) has been discussed.