An isocratic assay for norepinephrine, dopamine, and 5-hydroxytryptamine using their native fluorescence by high-performance liquid chromatography with fluorescence detection in discrete brain areas of rat

In-situ polyherbal gel as biomedicine in the management of Alzheimer's disease: Understanding ameliorative potential in Trimethyltin induced neurodegeneration

Alzheimer's disease (AD), classified as neurodegenerative disorder that progresses over a period of time, is characterized by intracellular neurofibrillary tangles and extracellular amyloid plaques. This present research work was designed to develop a polyherbal gel for the treatment of AD. This research study is aimed to confirm the impact and validation of polyherbal gel on tauopathy and neurodegeneration that had been induced by intraperitoneal trimethyltin (TMT) injection to rats. Polyherbal loaded gel was prepared by cold method, and characterized for gel strength, viscosity, permeation and pH. Subsequently, 5 marker based standardized plant materials of Kalyanka ghrita were incorporated in gellan gum and xanthan gum. Finally, an in-vivo investigation employing rats with TMT-induced neurological disease were used to assess the efficacy of the optimized gel. On day 7, the Wistar rats received intraperitoneal injections of TMT. From day 14 to day 35, the corresponding groups received intranasal administration of polyherbal gel. In addition to the molecular parameters such as brain acetyl cholinesterase activity, BDNF (Rat brain derived neurotropic factor), protein phosphatase 2 A, antioxidant parameters, and oxidative stress markers, the behavioral parameters were also determined. Studies were conducted on the brain's monoamine levels and histology. RESULTS: Higher permeation over the nasal mucosa was demonstrated by the optimized In-situ polyherbal gel. Significant improvement in cognition was observed from the reduced escape latency, longer paths, and increased social or novel object recognition tests post polyherbal gel treatment. A documented HPLC technique helped in optimization and standardization of the polyherbal gel. The polyherbal treatment groups exhibited a considerable rise in the levels of monoamines, including norepinephrine, dopamine, and 5-hydroxy tryptamine. CONCLUSION: According to the current study, treating Alzheimer's disease (AD) with a polyherbal gel formulation may be a viable option for successful therapy.

Acute Hypobaric Hypoxia Exposure Causes Neurobehavioral Impairments in Rats: Role of Brain Catecholamines and Tetrahydrobiopterin Alterations

Hypoxia is a state in which the body or a specific part of the body is deprived of adequate oxygen supply at the tissue level. Sojourners involved in different activities at high altitudes (> 2500 m) face hypobaric hypoxia (HH) due to low oxygen in the atmosphere. HH is an example of generalized hypoxia, where the homeostasis of the entire body of an organism is affected and results in neurochemical changes. It is known that lower O₂ levels affect catecholamines (CA), severely impairing cognitive and locomotor behavior. However, there is less evidence on the effect of HH-mediated alteration in brain Tetrahydrobiopterin (BH4) levels and its role in neurobehavioral impairments. Hence, this study aimed to shed light on the effect of acute HH on CA and BH4 levels with its neurobehavioral impact on Wistar rat models. After HH exposure, significant alteration of the CA levels in the discrete brain regions, viz., frontal cortex, hippocampus, midbrain, and cerebellum was observed. HH exposure significantly reduced spontaneous motor activity, motor coordination, and spatial memory. The present study suggests that the HH-induced behavioral changes might be related to the alteration of the expression pattern of CA and BH4-related genes and proteins in different rat brain regions. Overall, this study provides novel insights into the role of BH4 and CA in HH-induced neurobehavioral impairments.

Effect of Excessive Serotonin on Pharmacokinetics of Cephalexin after Oral Administration: Studies with Serotonin-Excessive Model Rats

PURPOSE

Serotonin (5-HT) is important for gastrointestinal functions, but its role in drug absorption remains to be clarified. Therefore, the pharmacokinetics and oral absorption of cephalexin (CEX) were examined under 5-HT-excessive condition to understand the role of 5-HT.

METHODS

5-HT-excessive rats were prepared by multiple intraperitoneal dosing of 5-HT and clorgyline, an inhibitor for 5-HT metabolism, and utilized to examine the pharmacokinetics, absorption behavior and the intestinal permeability for CEX.

RESULTS

Higher levels of 5-HT in brain, plasma and small intestines were recognized in 5-HT-excessive rats, where the oral bioavailability of CEX was significantly enhanced. The intestinal mucosal transport via passive diffusion of CEX was significantly increased, while its transport via PEPT1 was markedly decreased specifically in the jejunal segment, which was supported by the decrease in PEPT1 expression on brush border membrane (BBM) of intestinal epithelial cells. Since no change in antipyrine permeability and significant increase in FITC dextran-4 permeability were observed in 5-HT-excessive rats, the enhanced permeability for CEX would be attributed to the opening of tight junction, which was supported by the significant decrease in transmucosal electrical resistance. In 5-HT-excessive rats, furthermore, total body clearance of CEX tended to be larger and the decrease in PEPT2 expression on BBM in kidneys was suggested to be one of the reasons for it.

CONCLUSIONS

5-HT-excessive condition enhanced the oral bioavailability of CEX in rats, which would be attributed to the enhanced permeability across the intestinal mucosa via passive diffusion through the paracellular route even though the transport via PEPT1 was decreased.

Study on the Rapid Preparation of Zinc Oxide Nanotubes by Galvanostatic Etching

At present, most of the methods for preparing ZnO nanotubes are chemical etching of ZnO nanorods, which is inefficient and takes a long time. In this paper, ZnO nanotubes were successfully prepared by galvanostatic etching. Nanotubes prepared by galvanostatic etching only took 1/6 of the time of chemical etching. The ZnO nanotubes obtained by two different methods were tested by XRD and SEM. It is found that the crystal structure and crystallinity of the ZnO nanotubes obtained by galvanostatic etching are unchanged, and the internal corrosion of the nanotubes by galvanostatic etching is more thorough and has a larger specific surface area. In the tests of UV-vis spectrophotometry, fluorescence spectra and electrochemical performance test, the optical properties and electrochemical performance of ZnO nanotubes obtained by galvanostatic etching are better than those obtained by chemical etching. Because the ZnO nanotubes obtained by galvanostatic etching have larger specific surface area, better optical properties and better electrochemical performance, they have a greater application prospect in sensors and ultraviolet light detectors.

Pharmacological evaluation of vanillic acid in rotenone-induced Parkinson's disease rat model

In the present study, we investigated the anti-Parkinson's effect of vanillic acid (VA) (12 mg/kg, 25 mg/kg, 50 mg/kg p.o.) against rotenone (2 mg/kg s.c.) induced Parkinson's disease (PD) in rats. The continuous administration of rotenone for 35 days resulted in rigidity in muscles, catalepsy, and decrease in locomotor activity, body weight, and rearing behaviour along with the generation of oxidative stress in the brain (rise in the TBARS, and SAG level and reduced CAT, and GSH levels). Co-treatment of VA and levodopa-carbidopa (100 mg/kg + 25 mg/kg p.o.) lead to a significant (P < 0.001) reduction in the muscle rigidity and catalepsy along with a significant (P < 0.001) increase in body weight, rearing behaviour, locomotion and muscle activity as compared to the rotenone-treated group in the dose dependent manner, showing maximum effect at the 50 mg/kg. It also showed reversal of levels of oxidative stress parameters thus, reducing the neuronal oxidative stress. The level of DA was also estimated which showed an increase in the level of DA in the VA plus standard drug treated animals as compared to rotenone treated group. Histopathological evaluation showed a high number of eosinophilic lesions in the rotenone group which were found to be very less in the VA co-treated group. The study thus proved that co-treatment of VA and levodopa-carbidopa, significantly protected the brain from neuronal damage due to oxidative stress and attenuated the motor defects indicating the possible therapeutic potential of VA as a neuroprotective in PD.

Toxicity of ayahuasca after 28 days daily exposure and effects on monoamines and brain-derived neurotrophic factor (BDNF) in brain of Wistar rats

Ayahuasca is a hallucinogenic beverage that affects the serotonergic system and have therapeutic potential for many diseases and disorders, including depression and drug addiction. The objectives of this study were to evaluate the potential toxic effects of ayahuasca on rats after chronic exposure, and the levels of monoamines, their metabolites and the brain-derived neurotrophic factor (BDNF) in the brain. Female and male rats were treated orally for 28 days with H₂O (control), fluoxetine (FLX), a selective serotonin reuptake inhibitor antidepressant, or ayahuasca (Aya) at doses of 0.5X, 1X and 2X the ritualistic dose (7 to 10 animals/group). Clinical, hematological and macroscopic results showed that ayahuasca was safe to the rats. Behavior tests conducted one hour after the last treatment showed that male rats from the Aya1 group explored the open field central area less than the control group, and the number of entries in the central area compared to total locomotion was also significantly lower in this group and in the FLX group. The hippocampus was removed for BDNF analysis and the remaining brain was used for monoamine analysis by HPLC-FL. Serotonin levels were significantly higher than control only in the Aya2 female group, while a significant reduction of its metabolite 5-HIAA was observed in the FLX group. Dopamine levels were similar among the experimental groups, but the levels of its metabolite DOPAC increased significantly in the Aya1 and Aya2 groups compared to controls, especially in females, and the DOPAC/dopamine turnover was significantly higher in Aya2 group. The levels of HVA, another dopamine metabolite, did not change with the treatments compared to controls, but HVA/DOPAC ratio was significantly lower in all ayahuasca male groups. Norepinephrine was not detected in any brain sample, and the levels of its metabolite MHPG did not change significantly among the groups. BDNF levels in the hippocampus were significantly higher in the FLX and Aya2 female groups compared to controls when expressed in relation to the total brain weight. The mechanisms involved in the increase in serotonin, dopamine turnover and BDNF levels observed in ayahuasca treated animals should be further investigated in specific brain areas.

Potentiation of Antidepressant Effects of Agomelatine and Bupropion by Hesperidin in Mice

Hesperidin, a well-known flavanone glycoside mostly found in citrus fruits, showed neuroprotective and antidepressant activity. Agomelatine, a melatonergic MT1/MT2 agonist and 5-HT2C receptor antagonist, exhibits good antidepressant efficacy. Bupropion has been widely used for the treatment of depression because of its dopamine and norepinephrine reuptake inhibition. The objective of present study was to assess the antidepressant effects of hesperidin combination with agomelatine or bupropion. Male Swiss Albino mice received treatment of saline, vehicle, 'hesperidin alone', 'agomelatine alone', hesperidin+agomelatine, 'bupropion alone', hesperidin+bupropion, and agomelatine+bupropion for 14 days. The immobility period was analysed 30 min after the treatment in forced swim and tail suspension tests. Dopamine and serotonin levels were analysed in hippocampus, cerebral cortex, and whole brain using HPLC with fluorescence detector. Hesperidin plus agomelatine treated group was better in terms of decrease in immobility period and increase in dopamine and serotonin levels when compared to their respective monotherapy treated groups.

Validation of ethnopharmacology of ayurvedic sarasvata ghrita and comparative evaluation of its neuroprotective effect with modern alcoholic and lipid based extracts in β-amyloid induced memory impairment

ETHNOPHARMACOLOGICAL RELEVANCE

Sarasvata ghrita (SG), a polyherbal formulation from ayurveda, an ancient medicinal system of India, has been used to improve intelligence and memory, treat speech delay, speaking difficulties and low digestion power in children.

AIM OF THE STUDY

Study aimed to validate the ethno use of SG in memory enhancement through systematic scientific protocol. The effect of SG and modern extracts of ingredients of SG was compared on cognitive function and neuroprotection in amyloid-β peptide 25-35(Aβ25-35) induced memory impairment in wistar rats. Further the underlying mechanism for neuroprotective activity was investigated.

MATERIALS AND METHODS

SG was prepared as per traditional method, ethanolic extract (EE) was prepared by conventional method and lipid based extract was prepared by modern extraction method. All extracts were standardised by newly developed HPLC method with respect to marker compounds. SG, EE and LE were administered orally to male Wistar rats at doses of 100,200 and 400 mg/kg Body Weight by feeding needle for a period of 21 days after the intracerebroventricular administration of Aβ25-35 bilaterally. Spatial memory of rats was tested using Morris water maze (MWM) and Radial arm maze (RAM) test. The possible underlying mechanisms for the cognitive improvement exhibited by SG, EE and LE was investigated through ex-vivo brain antioxidant effect, monoamine level estimation, acetylcholine esterase (AchE) inhibitory effect and Brain-derived neurotropic factor (BDNF) levels estimation.

RESULTS

SG, EE and LE were analyzed by HPLC method, results showed that EE extract has high percent of selected phytoconstituents as compared with SG and LE. SG and LE decrease escape latency and searching distance in a dose dependant manner during MWM test. In case of RAM significant decrease in number of errors and increase in number of correct choices indicate an elevation in retention and recall aspects of learning and memory after administration of SG an LE. SG and LE extract can efficiently prevent accumulation of β-amyloid plaque in hippocampus region. There was increase in SOD, GSH, CAT and NO level and decrease in MDA levels in SG and LE administered animals. SG and LE have found to exhibit AchE inhibitiory activity and significant dose-dependant increase in BDNF level in the plasma. SG and LE significantly increased the levels of noradrenaline, dopamine and 5-hydroxytryptamine in the brain.

CONCLUSION

The study validated the neuroprotective activity of SG. The study concludes the extraction efficiency of SG for selected phytoconstituents is less than modern methods. However the neuroprotective activity of SG and LE was found to be greater than EE.

Neuroprotective effect of Indian propolis in β-amyloid induced memory deficit: Impact on behavioral and biochemical parameters in rats

The study aimed at the investigation of neuroprotective activity of macerated ethanolic extract of Indian propolis (MEEP) against β-Amyloid 25-35 (Aβ_25-35) induced memory impairment in Alzheimer's disease. MEEP was administrated orally to Wistar rats at doses of 100, 200 and 300mg/kg. Behavioral performances were evaluated using morris water maze and radial arm maze. At the end of behavioral study, the brains were removed and antioxidant parameters and brain monoamines were estimated. Further acetylcholinesterase (AchE) inhibition and brain-derived neurotropic factor (BDNF) were evaluated. In addition hematological parameters and histopathological tests were also carried out. In behavioral models, MEEP significantly (P<0.05) reversed the cognitive impairment of β amyloid-induced rats. The antioxidant potential was significantly increased (P<0.05) after administration of MEEP. Malondialdehyde levels were significantly (P<0.01) decreased in brain homogenate after treatment with MEEP extract as compared with diseased control group (group III). MEEP showed dose-dependent AChE inhibition and increased the levels of brain monoamines (P<0.05) as compared with group III. MEEP improved memory deficits by increasing BDNF in plasma (P<0.05). The study concludes that MEEP has anti-Alzheimer potential in rats through multiple mechanisms and further studies are ongoing for fractionation and biological screening.

Fast hepatic biotransformation of p-synephrine and p-octopamine and implications for their oral intake

Orally ingested p-synephrine, due to its fast transformation, may be acting primarily in the periportal region of the liver and only marginally in other tissues.

Tailored interfacial architecture of chitosan modified glassy carbon electrodes facilitating selective, nanomolar detection of dopamine

Chitosan was tailored directly on the electrode surface to detect DA selectively in nanomolar level at physiological pH.

Monoamine oxidase-A is an important source of oxidative stress and promotes cardiac dysfunction, apoptosis, and fibrosis in diabetic cardiomyopathy

Oxidative stress is closely associated with the pathophysiology of diabetic cardiomyopathy (DCM). The mitochondrial flavoenzyme monoamine oxidase A (MAO-A) is an important source of oxidative stress in the myocardium. We sought to determine whether MAO-A plays a major role in modulating DCM. Diabetes was induced in Wistar rats by single intraperitoneal injection of streptozotocin (STZ). To investigate the role of MAO-A in the development of pathophysiological features of DCM, hyperglycemic and age-matched control rats were treated with or without the MAO-A-specific inhibitor clorgyline (CLG) at 1 mg/kg/day for 8 weeks. Diabetes upregulated MAO-A activity; elevated markers of oxidative stress such as cardiac lipid peroxidation, superoxide dismutase activity, and UCP3 protein expression; enhanced apoptotic cell death; and increased fibrosis. All these parameters were significantly attenuated by CLG treatment. In addition, treatment with CLG substantially prevented diabetes-induced cardiac contractile dysfunction as evidenced by decreased QRS, QT, and corrected QT intervals, measured by ECG, and LV systolic and LV end-diastolic pressure measured by microtip pressure transducer. These beneficial effects of CLG were seen despite the persistent hyperglycemic and hyperlipidemic environments in STZ-induced experimental diabetes. In summary, this study provides strong evidence that MAO-A is an important source of oxidative stress in the heart and that MAO-A-derived reactive oxygen species contribute to DCM.

Atypical Antidepressant Activity of 3,4-Bis(3,4-Dimethoxyphenyl) Furan-2,5-Dione Isolated from Heart Wood of Cedrus deodara, in Rodents

Cedrus deodara (Pinaceae) has been used traditionally in Ayurveda for the treatment of central nervous system disorders. 3,4-bis(3,4-dimethoxyphenyl)furan-2,5-dione (BDFD) was isolated from heart wood of Cedrus deodara and was shown to have antiepileptic and anxiolytic activity. Thus, the present study was aimed to explore its anti-depressant effect and to correlate the effect with serotonin and nor adrenaline levels of brain. Albino mice were used as experimental animal. Animals were divided in to three groups; vehicle control, imipramine (30 mg/kg i.p.), BDFD (100 mg/kg i.p.). Tail suspension test (TST) and forced swim test (FST) was performed to evaluate antidepressant effect of BDFD. BDFD (100 mg/kg, i.p.) showed a significant decrease in immobility time when subjected to FST whereas immobility time was not significantly altered in TST. BDFD treatment increased serotonin and noradrenaline levels in the brain which is indicative of BDFD having possible atypical antidepressant action.

The Combination of Antidepressant Duloxetine with Piracetam in Mice does not Produce Enhancement of Nootropic Activity

There is a strong association between depression and memory impairment. The present study aims to assess the nootropic activity of duloxetine and piracetam combination. Male Swiss Albino mice were divided randomly into 4 groups. Treatment of normal saline (10 ml/kg), duloxetine (10 mg/kg), piracetam (100 mg/kg), and duloxetine (5 mg/kg) plus piracetam (50 mg/kg) were given through intra-peritoneal route to group I-IV, respectively. Transfer latency in elevated plus maze (EPM) and time spent in target quadrant in Morris water maze (MWM) were recorded. Estimation of brain monoamines in hippocampus, cerebral cortex, and whole brain were done using HPLC with fluorescence detector. Piracetam treated group showed significant decrease in transfer latency in EPM and increase in time spent in target quadrant recorded in MWM. Combination treated group failed to produce statistically significant nootropic effect in both EPM and MWM. Combination treated group failed to increase brain monoamine levels when compared against duloxetine and piracetam treated groups, separately. But there was exception of significant increase in norepinephrine levels in hippocampi when compared against duloxetine treated group. Results indicate no cognitive benefits with piracetam plus duloxetine combination. These findings can be further probed with the aim of understanding the interaction between duloxetine and piracetam as a future endeavor.

Synthesis and characterization of 4-(2-aminoethyl)aniline imprinted polymer as a highly effective sorbent of dopamine

The aim of the study was to develop an efficient sorbent for the separation of dopamine. 4-(2-Aminoethyl)aniline was chosen as a pseudo-template to produce the imprinted polymers from seven different functional monomers in the presence of ethylene glycol dimethacrylate as a cross-linker. The binding capacity showed that the highest binding specificity towards dopamine was achieved when methacrylic acid was used as the monomer in methanol solution to form a polymer matrix. The imprinting factor value was equal to 22.96. Other biogenic amines were bound much more weakly. A simple theoretical model was used to give an insight into the imprinting process and the selectivity of polymer matrix. Two artificial urine samples were used as the complex matrices to show the usefulness of the new sorbent for bioanalysis.

Ameliorative effect of Sida cordifolia in rotenone induced oxidative stress model of Parkinson's disease

Present study focused on the evaluation of aqueous extract of Sida cordifolia (AESC), and its different fractions; hexane (HFSC), chloroform (CFSC) and aqueous (AFSC), against rotenone induced biochemical, neurochemical, histopathological and behavioral alterations in a rat model of Parkinson's disease (PD). An estimation of the level of thiobarbituric acid reactive substances (TBARS), glutathione (GSH) and catalase (CAT) along with superoxide anion generation (SAG) in different brain regions (cortex, midbrain and cerebellum) was carried out to assess biochemical changes. Behavioral evaluation tests (catalepsy, rearing behavior and posture instability) and neurochemical estimations (norepinephrine, dopamine and serotonin level) along with histopathological evaluations of different brain regions were also performed. The varying doses (50, 100, 250mg/kg; p.o.) of different test treatments (AESC, HFSC, CFSC and AFSC) were co-administered along with rotenone (2mg/kg; s.c.), for a period of 35 days to rats of various groups and compared with rotenone per se (negative control) and l-deprenyl (positive control; 10mg/kg; p.o.) treated groups for the above mentioned parameters. The increase in catalepsy and posture instability along with decrease in rearing behavior observed due to rotenone treatment was significantly attenuated by co-treatment with varying doses of AESC and AFSC. Results of the histopathological studies of different brain regions of rats showed eosinophilic lesions in the mid brain region due to rotenone treatment. The eosinophilic lesions were significantly attenuated in co-treated groups of AESC-100mg/kg and AFSC-100mg/kg. Rotenone induced oxidative damage, revealed by increased level of TBARS, SAG and decreased level of GSH and CAT in mid brain region of rats, was attenuated by the co-treatment of AESC and AFSC. The rotenone induced decrease of dopamine level in the midbrain region of rats was also attenuated by co-treatment of AESC-100mg/kg and AFSC-100mg/kg. The maximum effect in all the above activities was observed in AFSC (100mg/kg) treated group, which was comparable to l-deprenyl treated group. The HFSC and CFSC co-treatment failed to show significant attenuation of rotenone induced damage. These results indicate the possible therapeutic potential of most polar fraction of AESC i.e. AFSC in PD by virtue of its antioxidative actions.

An interface for sensitive analysis of monoamine neurotransmitters by ion-pair chromatography-electrospray ionization-mass spectrometry with continuous online elimination of ion-pair reagents

A challenge in coupling ion-pair chromatography (IPC) online with electrospray ionization-mass spectrometry (ESI-MS) is that the nonvolatile ion-pair reagent (e.g., alkyl sulfate for amines or tetrabutylammonium for carboxylic acids) in the mobile phase suppresses the ESI-MS signals in the gas phase and their accumulation can clog the MS sampling interface. Consequently, IPC-ESI-MS is conducted either with a volatile ion-pair reagent, which could compromise the analyte separation efficiency, or with a downstream ion-exchange column to rid the ion-pair reagents of the mobile phase. In the latter approach, the limited capacity of ion-exchange columns requires frequent off-line column regeneration, which affects the separation throughput and prohibits long separations from being performed. A dual-valve, dual-ion exchange column interface of IPC-ESI-MS is designed for undisrupted separations and simultaneous column regeneration. Owing to the efficacy in removing the ion-pair reagent, the detection of eluents of monoamine neurotransmitters by an ion trap MS results in the limits of detection of 0.03 μM for dopamine or DA and 0.01 μM for 5-hydroxytryptamine or 5-HT. These values are lower than those obtained with ion trap MS of similar sensitivity when combined with the use of specialized chromatographic columns or sample preconcentration. Excellent reproducibility was attained with repeatedly regenerated ion-exchange columns (RSD = 4-6%) for an extended period of time (RSD < 6% for 6 days). DA and 5-HT in rat straital extracts were analyzed, and our data demonstrate that interferences inherent in the tissues and the ion-pair reagent have been successfully eliminated. This simple interface should be readily amenable to the separation and MS analysis of other types of polar compounds in complex sample media.

Effect of saponin fraction from Ficus religiosa on memory deficit, and behavioral and biochemical impairments in pentylenetetrazol kindled mice

In our previous study, the saponin-rich fraction (SRF) of adventitious root extract of Ficus religiosa L. (Moraceae) was shown to have an anticonvulsant effect in acute animal models of convulsions. The present study was envisaged to study the effect of SRF in the pentylenetetrazol (PTZ) kindling mouse model and its associated depression and cognition deficit. Treatment with the SRF (1, 2 and 4 mg/kg; i.p.) for 15 days in kindled mice significantly decreased seizure severity on days 5, 10 and 15 when challenged with PTZ (35 mg/kg; i.p.). Marked protection against kindling-associated depression was also observed on days 10 and 15 in the SRF-treated groups when tested using the tail-suspension test. However, the SRF treatment failed to protect kindling-associated learning and memory impairments in the passive shock avoidance paradigm. The observed behavioral effects were corroborated with modulation in the levels of noradrenaline, dopamine, serotonin, GABA and glutamate in discrete brain regions.

Involvement of the cerebral monoamine neurotransmitters system in antidepressant-like effects of a chinese herbal decoction, baihe dihuang tang, in mice model

Baihe Dihuang Tang (BDT) is a renowned Chinese herbal formula which is commonly used for treating patients with mental instability, absentmindedness, insomnia, deficient dysphoria, and other psychological diseases. These major symptoms closely associated with the depressive disorders. BDT was widely popular use for treating emotion-thought disorders for many years in China. In the present study, the antidepressant-like effect of BDT in mice was investigated by using the forced swim test (FST) and the tail suspension test (TST). The underlying mechanism was explored by determining the effect of BDT on the level of cerebral monoamine neurotransmitters. BDT (9 and 18 g/kg, p.o. for 14 days) administration significantly reduced the immobility time in both the FST and the TST without changing locomotion in the open field-test (OFT). Moreover, BDT treatment at the dose of 18 g/kg inhibited reserpine-induced ptosis. Meanwhile, BDT enhanced 5-HT and NA levels in mouse cerebrum as well as decreased the ratio of 5-HT compared to its metabolite, 5-HIAA, (turnover, 5-HIAA/5-HT) after TST. The results demonstrated that the antidepressant-like effect of BDT is mediated, at least partially, via the central monoaminergic neurotransmitter system.

Vacuolar H(+)-ATPase subunits Voa1 and Voa2 cooperatively regulate secretory vesicle acidification, transmitter uptake, and storage

Voa1 and Voa2 cooperatively regulate the acidification and transmitter uptake/storage of dense-core vesicles, although they might not be as critical for exocytosis as recently proposed.

The Vo sector of the vacuolar H⁺-ATPase is a multisubunit complex that forms a proteolipid pore. Among the four isoforms (a1–a4) of subunit Voa, the isoform(s) critical for secretory vesicle acidification have yet to be identified. An independent function of Voa1 in exocytosis has been suggested. Here we investigate the function of Voa isoforms in secretory vesicle acidification and exocytosis by using neurosecretory PC12 cells. Fluorescence-tagged and endogenous Voa1 are primarily localized on secretory vesicles, whereas fluorescence-tagged Voa2 and Voa3 are enriched on the Golgi and early endosomes, respectively. To elucidate the functional roles of Voa1 and Voa2, we engineered PC12 cells in which Voa1, Voa2, or both are stably down-regulated. Our results reveal significant reductions in the acidification and transmitter uptake/storage of dense-core vesicles by knockdown of Voa1 and more dramatically of Voa1/Voa2 but not of Voa2. Overexpressing knockdown-resistant Voa1 suppresses the acidification defect caused by the Voa1/Voa2 knockdown. Unexpectedly, Ca²⁺-dependent peptide secretion is largely unaffected in Voa1 or Voa1/Voa2 knockdown cells. Our data demonstrate that Voa1 and Voa2 cooperatively regulate the acidification and transmitter uptake/storage of dense-core vesicles, whereas they might not be as critical for exocytosis as recently proposed.

Alpha2-adrenoceptor blockade accelerates the neurogenic, neurotrophic, and behavioral effects of chronic antidepressant treatment

Slow-onset adaptive changes that arise from sustained antidepressant treatment, such as enhanced adult hippocampal neurogenesis and increased trophic factor expression, play a key role in the behavioral effects of antidepressants. alpha(2)-Adrenoceptors contribute to the modulation of mood and are potential targets for the development of faster acting antidepressants. We investigated the influence of alpha(2)-adrenoceptors on adult hippocampal neurogenesis. Our results indicate that alpha(2)-adrenoceptor agonists, clonidine and guanabenz, decrease adult hippocampal neurogenesis through a selective effect on the proliferation, but not the survival or differentiation, of progenitors. These effects persist in dopamine beta-hydroxylase knock-out (Dbh(-/-)) mice lacking norepinephrine, supporting a role for alpha(2)-heteroceptors on progenitor cells, rather than alpha(2)-autoreceptors on noradrenergic neurons that inhibit norepinephrine release. Adult hippocampal progenitors in vitro express all the alpha(2)-adrenoceptor subtypes, and decreased neurosphere frequency and BrdU incorporation indicate direct effects of alpha(2)-adrenoceptor stimulation on progenitors. Furthermore, coadministration of the alpha(2)-adrenoceptor antagonist yohimbine with the antidepressant imipramine significantly accelerates effects on hippocampal progenitor proliferation, the morphological maturation of newborn neurons, and the increase in expression of brain derived neurotrophic factor and vascular endothelial growth factor implicated in the neurogenic and behavioral effects of antidepressants. Finally, short-duration (7 d) yohimbine and imipramine treatment results in robust behavioral responses in the novelty suppressed feeding test, which normally requires 3 weeks of treatment with classical antidepressants. Our results demonstrate that alpha(2)-adrenoceptors, expressed by progenitor cells, decrease adult hippocampal neurogenesis, while their blockade speeds up antidepressant action, highlighting their importance as targets for faster acting antidepressants.

Nootropic activity of lipid-based extract of Bacopa monniera Linn. compared with traditional preparation and extracts

Objectives

The aim was to design an alternative solvent-free extraction method using the hydrophilic lipid Gelucire (polyethylene glycol glycerides) for herbal extraction and to confirm the efficacy of extraction using biological screening.

Methods

Bacopa monniera Linn. (BM) was selected for the study. Conventional methanolic extract (MEBM), Ayurvedic ghrita (AGBM) and lipid extracts (LEBM) were prepared and standardised by high-performance thin-layer chromatography (HPTLC). Nootropic activity in rats was evaluated using the two-trial Y-maze test and the anterograde amnesia induced by scopolamine (1 mg/kg i.p.) determined by the conditioned avoidance response. The extracts were administered daily at doses of 100, 200 and 400 mg/kg orally. At the end of the conditioned avoidance response test, brain monoamine levels were estimated by HPLC.

Key findings

The LEBM, MEBM and AGBM contained 3.56%, 4.10% and 0.005% bacoside A, respectively. Significantly greater spatial recognition was observed with LEBM (P &lt; 0.001 at 400 and 200 mg/kg) and MEBM (P &lt; 0.001 at 400 mg/kg, P &lt; 0.01 at 200 mg/kg) than AGBM. The conditioned avoidance response was significantly higher in the groups treated with high doses of LEBM and MEBM than AGBM. There were significant decreases in brain noradrenaline (P &lt; 0.001) and 5-hydroxytryptamine (P &lt; 0.01) levels and an increase in dopamine levels (P &lt; 0.05) in the LEBM-treated groups compared with the stress control group.

Conclusions

The proposed LEBM is solvent free, does not have the shortcomings associated with conventional extraction, and had comparable nootropic activity to the MEBM.

Stereotaxical infusion of rotenone: a reliable rodent model for Parkinson's disease

A clinically-related animal model of Parkinson's disease (PD) may enable the elucidation of the etiology of the disease and assist the development of medications. However, none of the current neurotoxin-based models recapitulates the main clinical features of the disease or the pathological hallmarks, such as dopamine (DA) neuron specificity of degeneration and Lewy body formation, which limits the use of these models in PD research. To overcome these limitations, we developed a rat model by stereotaxically (ST) infusing small doses of the mitochondrial complex-I inhibitor, rotenone, into two brain sites: the right ventral tegmental area and the substantia nigra. Four weeks after ST rotenone administration, tyrosine hydroxylase (TH) immunoreactivity in the infusion side decreased by 43.7%, in contrast to a 75.8% decrease observed in rats treated systemically with rotenone (SYS). The rotenone infusion also reduced the DA content, the glutathione and superoxide dismutase activities, and induced alpha-synuclein expression, when compared to the contralateral side. This ST model displays neither peripheral toxicity or mortality and has a high success rate. This rotenone-based ST model thus recapitulates the slow and specific loss of DA neurons and better mimics the clinical features of idiopathic PD, representing a reliable and more clinically-related model for PD research.

Dopamine-imprinted polymers: template-monomer interactions, analysis of template removal and application to solid phase extraction

A dopamine-imprinted polymer (MIP) was prepared in aqueous methanol solution at 60(o)C by free-radical cross-linking polymerization of methacrylic acid in the presence of ethylene glycol dimethacrylate as the cross-linker and dopamine hydrochloride as the template molecule. Its ability to isolate dopamine was evaluated as the basis of a solid phase extraction procedure and compared with that of a non-imprinted polymer(NIP). The binding of dopamine was 84.1% and 29.1% for MIP and NIP, respectively. Various reported post-polymerization treatments to reduce template bleeding were examined. In our case the lowest bleeding was achieved after applying a combined procedure: continuous extraction in a Soxhlet apparatus (CE), followed by microwave-assisted extraction (ME) to a level of 0.061 microg/mL. A simplified model of the template-monomer complexes allowed rationalization of monomer choice based on the heats of complex formation at a PM3 level of theory.

224nm deep-UV laser for native fluorescence, a new opportunity for biomolecules detection

A new highly sensitive and compact 224 nm laser-induced native fluorescence (LINF) detector was developed using a new generation of deep-UV laser and an innovating elliptical flow cell. The use of deep-UV excitation at 224 nm allows to achieve fluorescence detection of an important range of molecules containing a single aromatic ring. The LINF detector was first evaluated in liquid chromatography. An improvement of a factor 500 over a conventional fluorimeter is reached with a limit of detection (LOD) of 1.5 pmole for ibuprofen. LODs were in the nanomole range for phenylalanine and in the picomole range for tyrosine and tryptophan. The LINF detector is able to detect the same levels of peptides concentrations as an ESI-ion trap spectrometer used in scan mode. In this application, LINF outperforms the UV detection at 214 or 254 nm and could be used with different additives with no noticeable effect on the detection.

A New Spectrofluorimetric Method for Determination of Trace Amounts 5-Hydroxytryptamine in Human Urine and Serum

A new spectrofluorimetric method was developed for the determination of trace amount of 5-hydroxytryptamine (5-HT) in human urine and serum samples. In the NaAc-HAc buffer solution of pH=5.80, 5-HT can react with formaldehyde-acetylacetone system to form a new compound which sends yellow green fluorescence at 533 nm and the enhanced fluorescence intensity is in proportion to the concentration of 5-HT. Optimum conditions for the determination of 5-HT were also investigated. The dynamic range and detection limit for the determination of 5-HT are 5.35 x 10(-7) approximately 1.07 x 10(-4) mol/L and 2.08 x 10(-7) mol/L, respectively. The developed method is simple, practical and can be successfully applied to determination of 5-HT in human urine and serum samples. Moreover, the enhancement mechanisms of the fluorescence intensity in the 5-HT - formaldehyde-acetylacetone system have been also discussed.

Selective serotonin depletion does not regulate hippocampal neurogenesis in the adult rat brain: differential effects of p-chlorophenylalanine and 5,7-dihydroxytryptamine

Serotonin is suggested to regulate adult hippocampal neurogenesis, and previous studies with serotonin depletion reported either a decrease or no change in adult hippocampal progenitor proliferation. We have addressed the effects of serotonin depletion on distinct aspects of adult hippocampal neurogenesis, namely the proliferation, survival and terminal differentiation of hippocampal progenitors. We used the serotonin synthesis inhibitor p-chlorophenylalanine (PCPA) or the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) to deplete serotonin levels. 5,7-DHT selectively decreased hippocampal serotonin levels, while PCPA resulted in a significant decline in both serotonin and norepinephrine levels. We observed a robust decline in the proliferation and survival of adult hippocampal progenitors following PCPA treatment. This was supported by a decrease in the number of doublecortin-positive cells in the neurogenic niche in the hippocampus. In striking contrast, 5,7-DHT did not alter the proliferation or survival of adult hippocampal progenitors and did not alter the number of doublecortin-positive cells. The terminal differentiation of adult hippocampal progenitors was not altered by either PCPA or 5,7-DHT treatment. An acute increase in serotonin levels also did not influence adult hippocampal progenitor proliferation. These results suggest that selective serotonin depletion or an acute induction in serotonin levels does not regulate adult hippocampal neurogenesis, whereas treatment with PCPA that induces a decline in both serotonin and norepinephrine levels results in a significant decrease in adult hippocampal neurogenesis. Our results highlight the need for future studies to examine the role of other monoamines in both the effects of stress and antidepressants on adult hippocampal neurogenesis.

Selective Determination of Native Fluorescent Bioamines through Precolumn Derivatization and Liquid Chromatography Using Intramolecular Fluorescence Resonance Energy Transfer Detection

In this paper, we introduce a novel approach for the highly selective and sensitive analysis of native fluorescent bioamines (indoleamines and catecholamines). This method is based on intramolecular fluorescence resonance energy transfer (FRET) detection in a liquid chromatography (LC) system following precolumn derivatization of the bioamines' amino groups. In this detection process, we monitored the FRET from the native fluorescent moieties (donor) to the derivatized fluorophore (acceptor). From a screening study involving 15 fluorescent reagents, we found that o-phthalaldehyde (OPA) generated the FRET most effectively. The OPA derivatives of the native fluorescent bioamines emitted OPA fluorescence (445 nm) through an intermolecular FRET process when they were excited at the excitation maximum wavelengths of the native fluorescent bioamines (280 nm). The generation of FRET was confirmed through comparison with the analysis of a nonfluorescent amine (isoleucine) performed using LC and a three-dimensional fluorescence detection system. We were able to separate the OPA derivatives of the indoleamines and catecholamines when performing LC on an ODS column. The detection limits (signal-to-noise ratio, 3) for the indoleamines and catecholamines, at a 20-muL injection volume, were 17-120 and 28-200 fmol, respectively. The sensitivity of the intramolecular FRET-forming derivatization method is higher than those of systems that take advantage of both native fluorescence detection (i.e., without derivatization) and the conventional detection of OPA derivatives. Furthermore, this method provides enough selectivity and sensitivity for the determination of the indoleamines present in the urine of healthy humans.

Up-regulation of P-glycoprotein expression in small intestine under chronic serotonin-depleted conditions in rats

To investigate the role of serotonin (5-HT), an important neurotransmitter and hormone/paracrine agent in the small intestine, in the transport activity of P-glycoprotein (P-gp), the intestinal transport of quinidine, a P-gp substrate, was examined in 5-HT-depleted rats prepared by intraperitoneal administration of p-chlorophenylalanine, a specific inhibitor of tryptophan hydroxylase in 5-HT biosynthesis. In the in vitro transport study, quinidine transport across rat jejunum was significantly enhanced in both the secretory and absorptive directions under 5-HT-depleted conditions, although the secretory transport was still predominant. The electrophysiological study suggested that the quinidine transport via passive diffusion was enhanced presumably through a paracellular route. This might be due to looser tight junctions under 5-HT-depleted conditions. The voltage-clamp technique clearly indicated that the secretory transport of quinidine through the transcellular pathway was also enhanced by the depletion of 5-HT. Furthermore, 5-HT depletion increased verapamil-sensitive secretory transport of quinidine in rat jejunum. These results indicate that the secretory transport of quinidine via P-gp was significantly enhanced under 5-HT-depleted conditions. The level of ATP, an energy source for functioning P-gp, wet weight of jejunum, and total protein level in rat jejunal mucosa were not changed by 5-HT depletion, but the expression of P-gp in the brush-border membrane of rat jejunum was significantly induced, which is partly responsible for the enhancement of P-gp activity under the 5-HT-depleted condition.

Liquid chromatographic and tandem mass spectrometric assay for evaluation of in vivo inhibition of rat brain monoamine oxidases (MAO) A and B following a single dose of MAO inhibitors: application of biomarkers in drug discovery

A simple and selective assay for the evaluation of in vivo inhibition of rat brain monoamine oxidases (MAO) A and B following a single dose of MAO inhibitors was developed through the simultaneous determination of endogenous 5-hydroxy tryptamine, 5-hydroxyindole-3-acetic acid (5-HIAA), tryptophane, and 2-phenethylamine (PEA) in rat brain using liquid chromatography-tandem mass spectrometry (LC/MS/MS). These analytes were separated on a Zorbax SB-C18 column using a gradient elution with acetonitrile and 0.2% formic acid and detected on an electrospray ionization mass spectrometer in positive-ion multiple-reaction-monitoring mode. The susceptibility and variability of these analytes as potential biomarkers in response to MAO inhibition in vivo were evaluated after application to three MAO inhibitors, tranylcypromine, clorgyline, and pargyline. A dramatic increase (about 40-fold) in PEA brain level and a decrease in 5-HIAA by more than 90% were observed after administration of 15 mg/kg of the nonselective MAO inhibitor tranylcypromine. As expected, the brain level of PEA escalated to about 6-fold, while the 5-HIAA level remained unchanged following a dose of the MAO B inhibitor pargyline at 2mg/kg. In contrast, the brain level of 5-HIAA reduced by approximately 53%, but the PEA level was unaffected following the same dose of the MAO A inhibitor clorgyline. The results indicated that 5-HIAA and PEA were susceptible and effective biomarkers in the rat brain in response to MAO A and B inhibition, respectively. The LC/MS/MS method is useful not only for the determination of inhibitory potency but also for the differentiation of the selectivity of a MAO inhibitor against rat brain MAO A and B in vivo.

Determination of serotonin, noradrenaline, dopamine and their metabolites in rat brain extracts and microdialysis samples by column liquid chromatography with fluorescence detection following derivatization with benzylamine and 1,2-diphenylethylenediamine

A highly selective and sensitive column liquid chromatographic method for fluorescence determination of serotonin (5-HT), dopamine (DA), noradrenaline (NA) and their related metabolites 5-hydroxyindole-3-acetic acid (5-HIAA) and 3,4-dihydroxyphenylacetic acid (DOPAC) following derivatization with benzylamine and 1,2-diphenylethylenediamine (DPE) is described. The monoamines and the metabolites (20 microl samples) were derivatized in a two-step reaction, initiated with 20 microl of 0.3M benzylamine in 0.3M 3-cyclohexylaminopropanesulfonic acid (CAPS) buffer (pH 10.0), (for 5-HT, 5-HIAA, 2 min, 24 degrees C) and followed by 20 microl of 0.1M DPE in 0.3M glycine buffer (pH 10.0), (for DA, NA, DOPAC, 20 min, 50 degrees C). Both reagents contained 0.02 M potassium hexacyanoferrate(III) and 50% (v/v) methanol. The resulting highly fluorescent and stable benzoxazole derivatives were isocratically separated on a reversed-phase column (150 mm x 1.5 mm i.d., packed with C18 silica, 5 microm) within 45 min. Using fluorescence detection at ex. and em. wavelengths of 345 and 480 nm, respectively, the detection limit (signal-to-noise ratio of 3) for 5-HT, DA, NA, 5-HIAA, L-DOPA and DOPAC ranged between 0.08 and 5.65 fmol per 20-microl injection (12-847.5 pM in standard solution). The concentrations of monoamines (expressed in microg/g wet weight, mean +/- S.E.M., n=5) in tissue extracts from the rat striatum were: 0.45+/-0.05 (5-HT), 4.27+/-0.08 (DA), 0.27+/-0.04 (NA), 0.55+/-0.06 (5-HIAA), 1.26+/-0.16 (L-DOPA) and 1.62+/-0.11 (DOPAC). Microdialysis samples were collected in 20 min intervals from the probes implanted in the striatum of awake rats. The basal monoamine levels (in fmol/20 microl, mean +/- S.E.M., n=5) in the dialysates were: 4.0+/-0.7 (5-HT), 78.4+/-9.1 (DA), 6.4+/-0.8 (NA), 785.5+/-64.5 (5-HIAA) and 5504.5+/-136.5 (DOPAC). It is concluded that the new fluorescence derivatization protocol provides an excellent means for simultaneous determination of all three monoamines both in the complex samples (e.g. brain homogenates) and also at trace levels, such as those found in the microdialysis samples.

Role of noradrenergic fibers of the preoptic area in regulating sleep

The preoptic area (POA) has noradrenergic (NE) terminals, and this area controls sleep apart from body temperature and reproduction. The destruction of catecholaminergic (CA) terminals in the POA produced a decrease in sleep in rats. This effect was shown to be due to the destruction of NE and not dopaminergic terminals. The rats, which were hyperthermic after the destruction of CA fibers in the POA, preferred a lower ambient temperature. Though they were unable to have normal amount of sleep after lesion, it did not affect their behavioral thermoregulation. Acute total sleep deprivation for 48 h led to a significant decrease in noradrenaline, increase in the level of metabolites of monoamines, and an enhancement in the number of dendritic spines at the medial preoptic area (mPOA). Enhanced sleep pressure during sleep deprivation could have led to a higher release of noradrenaline, and an increase in dendritic spines in the mPOA. Arousal was produced by application of noradrenaline at the mPOA, whereas the alpha antagonists produced sleep in free-moving rats. This was in contrast to the increased wakefulness produced by the destruction of NE terminals. As wakefulness and sleep, respectively, were induced on local application of alpha-2 antagonist and agonists, it was suspected that the noradrenaline and alpha antagonists might have acted on the alpha-2 receptors, which are predominantly present on the pre-synaptic terminals. Sleep produced by noradrenaline, which was locally applied at the mPOA, after destroying the NE terminals, further confirmed this possibility. Hypothermia and sexual arousal produced by application of alpha- and beta-adrenergic agonists at the mPOA would have contributed towards the wakefulness induced by these drugs in normal rats. Thus, the available evidence shows that the NE fibers in the POA are involved in the induction of sleep.

Simultaneous determination of norepinephrine, serotonin, and 5-hydroxyindole-3-acetic acid in microdialysis samples from rat brain by microbore column liquid chromatography with fluorescence detection following derivatization with benzylamine

A microbore column liquid chromatographic method for the simultaneous determination of norepinephrine (NE), serotonin (5-HT), and 5-hydroxyindole-3-acetic acid (5HIAA) in microdialysis samples from rat brain is described. The method is based on precolumn derivatization of NE, 5HT, and 5HIAA with benzylamine in the presence of potassium hexacyanoferrate(III) resulting in the corresponding highly fluorescent and stable benzoxazole derivatives. A 15-microl sample was mixed with 15 microl derivatization reagent solution containing 0.3M 3-cyclohexylaminopropanesulfonic acid buffer (pH 12.0), 0.5M benzylamine, 10mM potassium hexacyanoferrate(III), and methanol (1/1/1/12, v/v/v/v). The derivatization was carried out at 50 degrees C for 20 min. The benzylamine derivatives of NE, 5HT, and 5HIAA were separated on a reversed-phase column (100 x 1.0mm i.d., packed with C18 silica, 5 microm) within 30 min. The mobile phase consisted of 15 mM acetate buffer (pH 5.0) and acetonitrile (31%, v/v); the flow rate was 50 microl/min. The detection limits (signal-to-noise ratio of 3) for NE, 5HT, and 5HIAA in the injection volume of 20 microl were 90, 210, and 260 amol, respectively. Microdialysis samples were collected in 7.5-min intervals from the probes implanted in the hippocampus and prefrontal cortex of awake rats. The basal levels of NE, 5HT, and 5HIAA in the dialysates from the hippocampus were 4.2+/-0.5, 4.9+/-0.6, and 934.1 +/- 63.4 fmol/20 microl, and those from the prefrontal cortex were 6.0+/-1.2,5.51.3, and 669.1 +/- 96.0 fmol/20 microl (mean +/- SE, n=25), respectively. The NE and 5HT levels were altered by perfusion of high-potassium or low-calcium solution and following antidepressant drugs imipramine and desipramine. It is concluded that the new fluorescence derivatization method in combination with microbore column liquid chromatography allows the simultaneous determination of NE, 5HT, and 5HIAA in the microdialysis samples at higher sensitivity, providing easier maintenance in routine use than that achieved by high-performance liquid chromatographic methods with electrochemical detection.

Synthesis and analysis of aminochromes by HPLC-photodiode array. Adrenochrome evaluation in rat blood

The catecholamine oxidation process induces cardiotoxicity and neurotoxicity. Catecholamines can oxidize to aminochromes through autoxidation or by enzymatic or non-enzymatic catalysis. Although some toxic effects seem to be related to the formation of aminochromes there is still scarce information concerning the identification and evaluation of these compounds in in vivo models. In this study five catecholamines were oxidized to their respective aminochromes: adrenaline/adrenochrome; noradrenaline/noradrenochrome; dopa/dopachrome; dopamine/dopaminochrome; and isoproterenol/isoprenochrome. The evaluation of the catecholamines oxidation profile was performed by HPLC with photodiode array detection and using either enzymatic (tyrosinase) or non-enzymatic [Ag(2)O, CuSO(4), NaIO(4) and K(3)Fe(CN)(6)] catalytic systems. The NaIO(4) was found to be the most efficient oxidant of catecholamines. An isocratic reverse-phase HPLC method was developed to analyse each pair of catecholamine-aminochrome. The analytical system was then applied to the detection of adrenochrome in rat blood at 490 nm. Thus, adrenochrome was administered i.p. to rats and its concentration in whole blood was monitored after 5, 15 and 25 min. Blood treatment for adrenochrome evaluation consists of an acidification for protein precipitation followed by a rapid neutralization. The results showed a rapid decrease of adrenochrome concentration in blood after its administration. The adrenochrome present in blood was characterized by UV and tandem mass spectrometry.

Restraint stress-induced alterations in the levels of biogenic amines, amino acids, and AChE activity in the hippocampus

Inspite of large number of studies on the neurochemical changes in the stress, an equivocal case is yet to be made for the role of a specific neurotransmitter in this important neurobiological disorder. The difficulty arises from the fact that there is no single neurotransmitter system appears to be responsible for the stress induced damage to the hippocampal neurons. The present study evaluates the effect of restraint stress on the alterations in the levels of biogenic amines, aminoacids and acetylcholinesterase activity in the hippocampus. Male Wistar rats of 45 days old were subjected to 6 hours of daily restraint stress over a period of 21 days. Immediately after the last session of stress, rats were sacrificed and neurotransmitter levels were estimated in the hippocampus. A significant (p < 0.001) decrease in the levels of noradrenaline, dopamine, 5-hydroxytryptamine and acetylcholinesterase activity in the stressed rats was observed compared to controls. However, levels of glutamate was significantly (p < 0.001) increased in stressed rats. These results indicate that chronic restraint stress decreases aminergic and cholinergic neurotransmission, and increases the glutamatergic transmission in the hippocampus.

Reversed-phase high-performance liquid chromatography of catecholamines and indoleamines using a simple gradient solvent system and native fluorescence detection

A reversed-phase HPLC method using a C18 column and a two-mobile-phase gradient elution system containing only volatile components has been developed for separation of norepinephrine, octopamine, epinephrine, dopamine, dihydroxyphenylalanine, tyramine, tyrosine, serotonin, 5-hydroxytryptophan, N-acetyl-serotonin and tryptophan. Mobile phase A contains 0.05% aqueous trifluoroacetic acid and methanol (97.5:2.5, v/v) and mobile phase B contains 0.05% aqueous trifluoracetic acid and methanol (40:60, v/v). This method has the advantage that the mobile phase can be removed completely, without salt residues, from the eluted fractions thus simplifying further analytical procedures on isolated fractions. The elution profile of standards is related to structural characteristics allowing prediction of retention times of known compounds and insight into possible structural characteristics of unknown components in a mixture. Detection is via native fluorescence using excitation at 220 nm and emission at 320 nm and under the conditions described has a sensitivity range from 2.5 to 25 pmol, although the sensitivity range can be extended depending on the emission wavelength used.

High-performance liquid chromatography of monoamines on phenyl-bound sorbents using organic free mobile phases

Tryptophan and its metabolites, 5-hydroxytryptophan, 5-hydroxytryptamine, 5-hydroxyindolacetic acid, as well as dopamine, homovanilic acid and 2,3-dihydroxyphenylacetic acid, were separated on phenyl bound silica gel using isocratic elution with phosphate buffer. The method was successfully transferred to several other phenyl HPLC columns from different manufacturers simply by adjusting the pH of the buffer. The method has been validated by the determination of the level of monoamines in rat hypothalamus.