Different patterns of CSF neurotransmitter metabolism in patients with left or right hemispheric stroke

Practical Application of Biogenic Amine Profiles for the Diagnosis of Patients with Ischemic Stroke

BACKGROUND

Ischemic stroke (IS) is still one of the major issues in medicine. Still, early diagnosis and misdiagnosis remain the main barriers for proper patient treatment and follow-up. Exploring new potential diagnostic biomarkers for IS is relevant to decrease patient morbidity and the occurrence of poststroke diseases. Biomedical analysis could bring new light to the background of IS and-in such a way-propose new bioanalytical tools for the early diagnosis, prognostication, and monitoring of IS.

MATERIALS AND METHODS

This research aimed to present a discussion on the employment of biogenic amines (BAs), as well as their precursory amino acids and main metabolites, as a new panel of biomarkers for IS. Preliminary patient data were presented and the patients were described with respect to their clinical history and examination records, as well as scientific data gained from the liquid extraction-capillary electrophoresis determination of BAs in the patients' urine samples.

RESULTS

The results showed the potential of BA screening using the developed sample preparation and analysis methods in urine during IS, and this will be further studied on a more numerous group of patients with IS to reveal the usefulness of BAs as a new panel of biomarkers for early IS diagnosis and prognostication.

CONCLUSIONS

To our best knowledge, this methodology for the first time has been used for the simultaneous analysis of multiple small molecular biomarkers. In addition, the factors that might influence the determination of BAs in real samples were pointed out.

HILIC-MS Rat Brain Analysis, A New Approach for the Study of Ischemic Attack

Clinicians often rely on selected small molecular compounds from body fluids for the detection, screening or monitoring of numerous life-threatening diseases. Among others, important monoamines - biogenic amines (BAs) - and their metabolites serve as sensitive biomarkers to study the progression or even early detection of on-going brain pathologies or tumors of neuroendocrine origins. Undertaking the task to optimize a reliable method for the simultaneous analysis of the most relevant BAs in biological matrices is of utmost importance for scientists. Hydrophilic interaction liquid chromatography (HILIC) with mass spectrometry (MS) detection provides a specific and sensitive technique for the separation and assessment of several neurotransmitter concentrations in body fluids (blood, urine, tissues). The present study was focused on the optimization of a straightforward, sensitive and reliable method for the simultaneous analysis of the ten most important BAs and their acidic metabolites from homogenates of rat brain tissues by use of HILIC-MS. Here, we present the optimized experimental workflow in terms of sample preparation, buffer compositions, HILIC and MS settings and data analysis. The presented method is reliable, straightforward and sensitive. Our method permits the unbiased, qualitative and quantitative determination of several BAs and their metabolites simultaneously. The optimized method was applied to the analysis of rat brain tissue samples from healthy hemispheres or those with induced transient ischemic attack (TIA). The undertaken pilot study demonstrated that the proposed approach could be applied to reveal the perturbation in neurotransmitters concentration after TIA in rat brains.

Decreased expression of serotonin 1A receptor in the dentate gyrus in association with chronic mild stress: a rat model of post-stroke depression

Alterations of serotonin (5-HT) neurotransmission are implicated in post-stroke depression (PSD). Serotonin 1A (5-HT(1A)) receptor-based abnormalities have been the focus of intensive study in depression. Here we investigated the expression of the 5-HT(1A) receptor and gene in the hippocampal dentate gyrus (DG) by chronic mild stress (CMS) after stroke and the effect of citalopram. Male Sprague-Dawley rats were separated into control, stress only, ischemic stroke, PSD and citalopram-treated groups. The putative PSD animal model involved cerebral ischemia induced by left middle cerebral artery occlusion (MCAO) followed by exposure to CMS combined with single housing. All animals were assessed for depression-like behavior. The 5-HT(1A) receptor and mRNA level in DG were quantified by Western immunoblotting and Real-time RT-PCR, respectively, on the 19th and 28th days after initiating CMS. PSD animals displaying a behavioral index of depression (anhedonia) have significantly decreased protein expression of 5-HT(1A) receptors and mRNA level relative to ischemic stroke animals at each timepoint, respectively, and all these were reversed by citalopram. The dysfunction of the of 5-HT(1A) receptor in DG may play an important role in the pathogenesis of PSD and become a potential target for therapeutic intervention in the rat. The results provide partial support for the psychosocial and biological etiology of PSD and further predict the etiologic validity of the PSD model.

A neuroendocrine study of serotonin function in depressed stroke patients compared to non depressed stroke patients and healthy controls

OBJECTIVES

We employed a neuroendocrine challenge paradigm to study serotonergic abnormalities associated with poststroke depression.

METHOD

Twelve depressed stroke patients (major depression N= 5, minor depression N = 7), 8 nondepressed stroke patients and 12 healthy volunteers completed a single-blind, placebo-controlled, challenge tests. Baseline cortisol (CORT) and prolactin (PRL) values, and these hormonal responses to 30 mg of oral d-FEN and placebo over a 4 hour period were measured in the three groups.

RESULTS

There were intergroup differences for baseline adjusted PRL responses (change scores from baseline) to d-FEN (group effect F = 4.38, df = 2,29, p = 0.02) while these responses to placebo were comparable between groups (group effect F = 1.82, df = 2,29, p = 0.18). Peak PRL responses (post d-FEN maximal PRL change from baseline scores) in depressed stroke patients were significantly greater than in nondepressed patients (p = 0.005) but comparable to healthy normals (p = 0.47). However, these responses between major and minor depression were not significant (p = 0.34). There was a trend suggesting a negative correlation between peak PRL response and severity of depression (p = 0.056). Depressed patients were younger than the controls (p = 0.054). Also, the depressed group was more functionally impaired (p = 0.04) and more likely to have right-sided lesions (p = 0.009) compared with the nondepressed group. Differences in baseline adjusted PRL changes between depressed and nondepressed groups became non significant when the influence of laterality of lesions was covaried, whereas covariation of functional scores and age did not alter the significance. CORT responses did not show intergroup differences.

LIMITATIONS

The study group was small and was heterogenous in lesion characteristics, time since stroke and type of depression. A fixed-order design was used in the challenge test paradigm.

CONCLUSIONS

When laterality of stroke lesion was taken into account, depressed and nondepressed stroke patients did not differ in PRL responses to d-FEN.

Diminished serotonin-mediated prolactin responses in nondepressed stroke patients compared with healthy normal subjects

BACKGROUND AND PURPOSE

The purpose of this study was to use hormonal responsiveness to d-fenfluramine (d-FEN) challenge as a measure of central serotonin (5-HT) function in a comparative evaluation of serotonergic abnormalities between stroke patients and healthy elderly normal subjects to test the hypothesis that stroke may be associated with diminished serotonergic functioning.

METHODS

Eight nondepressed medically stable stroke patients and 12 healthy volunteers completed a single-blind, placebo-controlled, fixed-order, crossover design challenge test with 30 mg of oral d-FEN. Baseline prolactin (PRL) and cortisol (CORT) and hormonal responses to d-FEN and placebo were measured at hourly intervals over a 4-hour period. Cardiovascular responses (pulse and blood pressure) and behavioral responses were also recorded at the same time points.

RESULTS

The 2 groups were comparable in demographics, body weight, plasma drug concentration, and behavioral and CORT responses. A 3-way ANOVA for repeated measures showed group differences for baseline adjusted PRL responses (change of scores from baseline). Peak PRL responses (maximal PRL change from baseline scores after treatment with d-FEN) in nondepressed stroke patients were attenuated compared with healthy elderly subjects, suggesting diminished serotonergic responsiveness in stroke patients.

CONCLUSIONS

The demonstrated serotonergic hypofunctioning poststroke may contribute to the high incidence of depressive disorders in stroke patients. Serotonergic agents may have a role in augmentation of stroke recovery.

A long-term follow-up study of cerebrospinal fluid 5-hydroxyindoleacetic acid in delirium

Cerebrospinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA) was determined for elderly delirious patients during the acute stage and after a 1-year follow-up period, and the 5-HIAA levels were compared with age-equivalent controls. As compared with the controls, the 5-HIAA levels were significantly higher at the beginning of the index admission in patients with multi-infarct dementia and patients with no apparent CNS disease. The 5-HIAA levels were also higher in the latter subgroup in the 1-year sampling, but no other differences between delirious patients and controls were observed. The one-way procedure showed no differences between the subgroup means of delirious patients when divided according to the severity of cognitive decline or type of delirium in any of the samples. The 5-HIAA levels measured during the index admission correlated with the length of life after delirium suggesting that serotonergic dysfunction may have prognostic significance in delirious patients.

Serotonin release into plasma during common carotid artery thrombosis in rats

BACKGROUND AND PURPOSE

We have tested the hypothesis that platelet-derived serotonin is released into the bloodstream during cerebrovascular thrombosis.

METHODS

Nonocclusive common carotid artery thrombosis was produced photochemically in 22 anesthetized adult male Wistar rats using the photosensitizing dye rose bengal and irradiation with an argon-pumped dye laser. Plasma serotonin levels were recorded before, during, and after photothrombosis by intra-arterial in vivo microdialysis with the probe placed distal to the site of thrombosis.

RESULTS

During and immediately after the common carotid artery thrombosis, serotonin levels increased significantly to a peak value of 781 nmol/l (p less than 0.001 by analysis of variance), representing a 15-fold increase compared with baseline levels. The increased serotonin levels gradually decreased but remained significantly elevated for 90 minutes. Ultrastructural analysis of the carotid thrombi identified a dense mass of aggregated platelets at various stages of degranulation.

CONCLUSIONS

These results are the first to demonstrate directly that serotonin accumulation occurs in plasma during and after the acute phase of common carotid artery thrombosis. Increased plasma serotonin levels may play a major role in the cerebral blood flow and blood-brain barrier abnormalities previously documented in this model of large-vessel thrombotic stroke.

Asymmetrical brain modulation of the immune response

It is now well known that the central nervous system can regulate the immune system. Interestingly the two sides of the brain have been demonstrated to be differently involved in the modulation of immune responses. In rodents, lesions of right or left neocortex induced opposite effects on various immune parameters including mitogen-induced lymphoproliferation, interleukin-2 production, macrophage activation or natural killer cell activity. Furthermore in humans, left-handedness has been reported to be associated with a high incidence of immune disorders. Likewise in mice, the direction of a lateralized motor behavior, i.e., paw preference in a food reaching task, correlated with an asymmetrical pattern of brain organization, was shown to be associated with lymphocyte reactivity, natural killer cell activity and auto-antibody production. Conversely the immune system could send to the brain information that may be asymmetrically expressed. The experimental models for investigating asymmetrical brain modulation of the immune system may be useful for studying physiological, pathological and genetic aspects of neuroimmunomodulation.

Asymmetrical effects of cortical ablation on brain monoamines in mice

Neurochemical changes induced by right or left cortical ablation which have previously been described to have immunological effects were investigated in mice. Catecholamine and indolamine levels were determined in the contralateral cortex and in subcortical structures involved in immunoregulation 14 and 60 days after unilateral cortical ablation. Unilateral cortical ablation induced profound and widespread changes in the contralateral cortex but also in subcortical regions of both sides at 14 days after surgery. Lesions of the left neocortex appeared mainly to affect the activity of serotoninergic inputs to the right neocortex, whereas ablations of the right cortex influenced the activity of the catecholaminergic inputs to the left. Sixty days after surgery, modifications in monoamine levels were observed only in the ipsilateral, but not contralateral, subcortical regions, the only exception being that DA turnover in the tuberoinfundibular system remained lowered in both hemispheres after either right or left cortical ablations. Furthermore, some asymmetrical effects of cortical lesions depended on functional brain lateralization as assessed by paw preference. It may be hypothesized that some neurochemical modifications induced by unilateral cortical lesions are, at least partially, responsible for the immunological perturbations observed after cortical ablation.