Migraine patients show an increased density of dopamine D3 and D4 receptors on lymphocytes

The effects of greater occipital nerve blockage with lidocaine on sleep characteristics in chronic migraine patients

PURPOSE

The aim of our study was to determine the effects of greater occipital nerve block (GONB) with lidocaine on sleep characteristics in patients with chronic migraine.

MATERIALS AND METHODS

Twenty female patients who underwent GONB with lidocaine were included in the study. The Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), Pre-Sleep Arousal Scale (PSAS), Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS), Restless Legs Syndrome Severity Scale (RLSSS), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and headache diary results before and after the treatment of the patients were compared.

RESULTS

We included 20 patients (all females) in our study. The mean age was 35.80 ± 8.82 years (range 24-50). After GON blockade, the number of days with pain (p < 0.001), duration of pain (p < 0.001), and Visual Analog Scale (VAS) score (p < 0.001) were significantly lower than before. After GONB, BDI (p = 0.007), BAI (p = 0.022), ISI (p = 0.009), and PSQI (p = 0.026) scores were significantly lower than before. After GONB, sleep quality was better than before (p = 0.035).

CONCLUSION

This study showed that GONB with lidocaine can improve sleep quality, insomnia, and symptoms of depression and anxiety while reducing migraine headache.

Potential biomarkers of addiction identified by real-time PCR in human peripheral blood lymphocytes: a narrative review

Addiction-related neurobiological factors could be considered as potential biomarkers. The concentration of peripheral biomarkers in tissues like blood lymphocytes may mirror their brain levels. This review is focused on the mRNA expression of potential addiction biomarkers in human peripheral blood lymphocytes (PBLs). PubMed, EMBASE, Web of Science, Scopus and Google Scholar were searched using the keywords 'addiction', 'biomarker', 'peripheral blood lymphocyte', 'gene expression' and 'real-time PCR'. The results showed the alterations in the regulation of genes such as dopamine receptors, opioid receptors, NMDA receptors, cannabinoid receptors, α-synuclein, DYN, MAO-A, FosB and orexin-A as PBLs biomarkers in addiction stages. Such variations could also be found during abstinence and relapse. PBLs biomarkers may help in drug development and have clinical implications.

Refractory migraine profile in CGRP-monoclonal antibodies scenario

Objective

Refractory migraine (Ref‐M) represents a conundrum that headache experts have to face with. We aim to investigate whether a peculiar profile may characterize patients with Ref‐M according to 2020 European Headache Federation criteria. Furthermore, to substantiate a dysfunctional dopaminergic pathway involvement in these patients, we explored the effectiveness of olanzapine.

Materials & Methods

Eighty‐four patients (fitting previous Ref‐M criteria of the 2014) were treated with erenumab for six months. Differences between clinical and demographic features of responder (Ref‐M according to 2014 criteria) and not‐responder (Ref‐M according to 2020 criteria) patients to CGRP‐mAbs were investigated and their predictive values assessed. In fifteen patients with Ref‐M not responders to CGRP‐mAbs, olanzapine was administered (5 mg/die) for 3 months and frequency and pain intensity of migraine attacks were estimated.

Results

Patients with Ref‐M not responsive to CGRP‐mAbs (29/84) when compared with Ref‐M responsive to CGRP‐mAbs showed higher baseline frequency of migraine attacks, medication overuse and pain catastrophizing scale (PCS) scores. Logistic regression analyses showed that frequency of attacks, medication overuse and PCS score represent independent negative predictors of CGRP‐mAbs response. A ≥50% reduction of headache days/month was observed after olanzapine treatment in 67% of patients with Ref‐M not responsive to CGRP‐mAbs.

Conclusions

We outline that higher frequency of migraine attacks, medication overuse and pain catastrophizing characterize patients with Ref‐M not responsive to CGRP‐mAbs. In this frame, olanzapine effectiveness on frequency and pain intensity of migraine attacks supports the hypothesis that migraine refractoriness may be subtended by a prominent involvement of the dopaminergic pathway.

A link between gastrointestinal disorders and migraine: Insights into the gut-brain connection

Background

Migraine is a complex, multifaceted, and disabling headache disease that is often complicated by gastrointestinal (GI) conditions, such as gastroparesis, functional dyspepsia, and cyclic vomiting syndrome (CVS). Functional dyspepsia and CVS are part of a spectrum of disorders newly classified as disorders of gut–brain interaction (DGBI). Gastroparesis and functional dyspepsia are both associated with delayed gastric emptying, while nausea and vomiting are prominent in CVS, which are also symptoms that commonly occur with migraine attacks. Furthermore, these gastric disorders are comorbidities frequently reported by patients with migraine. While very few studies assessing GI disorders in patients with migraine have been performed, they do demonstrate a physiological link between these conditions.

Objective

To summarize the available studies supporting a link between GI comorbidities and migraine, including historical and current scientific evidence, as well as provide evidence that symptoms of GI disorders are also observed outside of migraine attacks during the interictal period. Additionally, the importance of route of administration and formulation of migraine therapies for patients with GI symptoms will be discussed.

Methods

A literature search of PubMed for articles relating to the relationship between the gut and the brain with no restriction on the publication year was performed. Studies providing scientific support for associations of gastroparesis, functional dyspepsia, and CVS with migraine and the impact these associations may have on migraine treatment were the primary focus. This is a narrative review of identified studies.

Results

Although the association between migraine and GI disorders has received very little attention in the literature, the existing evidence suggests that they may share a common etiology. In particular, the relationship between migraine, gastric motility, and vomiting has important clinical implications in the treatment of migraine, as delayed gastric emptying and vomiting may affect oral dosing compliance, and thus, the absorption and efficacy of oral migraine treatments.

Conclusions

There is evidence of a link between migraine and GI comorbidities, including those under the DGBI classification. Many patients do not find adequate relief with oral migraine therapies, which further necessitates increased recognition of GI disorders in patients with migraine by the headache community.

Serotonin and dopamine receptors profile on peripheral immune cells from patients with temporal lobe epilepsy

The role of inflammation and immune cells has been demonstrated in neurological diseases, including epilepsy. Leukocytes, as well as inflammatory mediators, contribute to abnormal processes that lead to a reduction in seizure threshold and synaptic reorganization. In this sense, identifying different phenotypes of circulating immune cells is essential to understanding the role of these cells in epilepsy. Immune cells can express a variety of surface markers, including neurotransmitter receptors, such as serotonin and dopamine. Alteration in these receptors expression patterns may affect the level of inflammatory mediators and the pathophysiology of epilepsy. Therefore, in the current study, we evaluated the expression of dopamine and serotonin receptors on white blood cells from patients with temporal lobe epilepsy with hippocampal sclerosis (TLE-HS). Blood samples from 17 patients with TLE-HS and 21 controls were collected. PBMC were isolated and stained ex vivo for flow cytometry. We evaluated the expression of serotonin (5-HT_1A, 5-HT_1B, 5-HT₂, 5-HT_2B, 5-HT_2C, 5-HT₃, 5-HT₄), and dopamine receptors (D₁, D₂, D₃, D₄, and D₅) on the cell surface of lymphocytes and innate immune cells (monocytes and granulocytes). Our results demonstrated that innate cells and lymphocytes from patients with TLE-HS showed high mean fluorescent intensity (MFI) for 5-HT_1A, 5-HT_1B, 5-HT_2A, and 5-HT₄ compared to controls. No difference was observed for 5-HT_2B. For dopamine receptors, the expression of D₁, D₂, D_4, and D₅ receptors was higher on innate cells from patients with TLE-HS when compared to controls for the MFI. Regarding lymphocytes population, D₂ expression was increased in patients with TLE-HS. In conclusion, there are alterations in the expression of serotonin and dopamine receptors on immune blood cells of patients with TLE-HS. Although the biological significance of these findings still needs to be further investigated, these changes may contribute to the understanding of TLE-HS pathophysiology.

Dopaminergic symptoms in migraine: A cross-sectional study on 1148 consecutive headache center-based patients

BACKGROUND

Dopaminergic symptoms may be extremely pronounced in some migraine patients during the attack, representing a major source of disability.

OBJECTIVES

We aimed to carefully characterize the clinical picture of migraine patients with dopaminergic symptoms in a large patients' population as a putative migraine endophenotype, allowing more precise disease management, treatment and outcome prediction.

METHODS

We screened 1148 consecutive tertiary care episodic and chronic migraine patients with face-to-face interviews collecting thorough data on lifestyle, socio-demographic factors, and clinical migraine features.

RESULTS

We identified 374 patients with migraine with dopaminergic symptoms (32.6%). The most frequent dopaminergic symptom was yawning followed by somnolence, nausea, vomiting, fatigue, mood changes and diuresis. Migraine patients with dopaminergic symptoms had longer attack duration (OR: 1.82; 95% CI: 1.41-2.36, p < 0.0001), more frequent osmophobia (OR: 2.01; 95% CI: 1.50-2.69, p < 0.0001), allodynia (OR: 1.43; 95% CI: 1.10-1.85, p = 0.0071) and unilateral cranial autonomic symptoms (OR: 1.31; 95% CI: 1.01-1.68, p = 0.045), but used less preventative treatments (OR: 0.74; 95% CI: 0.57-0.98, p = 0.033) than patients without dopaminergic symptoms.

CONCLUSIONS

Migraine patients with dopaminergic symptoms are characterized by a full-blown, more disabling migraine. Dopaminergic system modulation should be carefully considered in individuals with migraine with dopaminergic symptoms for both acute and preventative treatments in future ad hoc designed studies.

The Relationship Between Parental Care and Pain in Children With Headache: A Narrative Review

PURPOSE

In migraine or primary headache in children, parents play a fundamental role in pain management. For this narrative review, PubMed, Google Scholar, and Psych Info were searched using the terms "parent headache", "mother/father headache", "parental impact headache", "alexithymia parents headache", "catastrophizing parent headache", "family headache", "children parent headache", and "quality of life family headache". Articles were chosen for inclusion based on their relevance in to the topic.

OVERVIEW

Several parental and psychological characteristics can influence in children and adolescent headache, such as parental attitudes as oppressive or overprotective; punitive parenting styles; familial psychological symptoms, especially anxiety and depression; catastrophizing about their child's pain or excessive worry about their child's headache; inability to express emotions; and feelings that may lead to somatization problems.

DISCUSSION

Parents' attitudes and behaviors toward their child's headache have a strong relation with the severity of headache attacks. Mothers seem to have more influence than fathers on children's pain and emotional regulation. We suggest that the presence of caregiver-child transmission of maladaptive coping strategies, arising from difficulties expressing emotion, may lead to incorrect management of headache pain, further facilitating headache chronification.

Interaction of neurotransmitters and neurochemicals with lymphocytes

Neurotransmitters and neurochemicals can act on lymphocytes by binding to receptors expressed by lymphocytes. This review describes lymphocyte expression of receptors for a selection of neurotransmitters and neurochemicals, the anatomical locations where lymphocytes can interact with neurotransmitters, and the effects of the neurotransmitters on lymphocyte function. Implications for health and disease are also discussed.

Multimorbidity in patients with chronic migraine and medication overuse headache

OBJECTIVES

Patients with chronic migraine (CM) display a considerable amount of comorbidities, particularly psychiatric and cardiovascular, and the presence of multiple comorbidities, that is, the so-called multimorbidity, is a risk factor for migraine chronification or maintenance of CM. Our aim was to address the rate and impact of multimorbidity in patients with CM and medication overuse headache (MOH).

MATERIALS & METHODS

In a sample of patients with CM attending a structured withdrawal for coexisting MOH, we defined multimorbidity as the presence of two or more conditions in addition to CM-MOH. We compared patients with and without multimorbidity for demographic and clinical variables, quality of life, and disability; we also tested whether patients with multimorbidity had higher likelihood to attend emergency room, relapse into CM, and require further withdrawal treatments by 12 months.

RESULTS

One hundred and ninety-four patients were enrolled as follows: 61% had at least one comorbidity, the most common being mental (34%), circulatory (18%), and endocrine conditions (13%); 32% were multimorbidity cases. Patients with multimorbidity had higher headaches frequency, older age, lower education and lower employment rates, higher disability and lower QoL. They were more frequently opioids/barbiturates overusers and were more likely to attend ER (OR: 2.36), relapse into CM (OR: 2.19), and undergo another withdrawal (OR: 2.75) by 12 months after discharge, after controlling for age, gender, years of education, and headache frequency.

CONCLUSIONS

Recognizing multimorbidity in patients with CM-MOH is important to enhance the management of these complex patients, who are at risk of polypharmacy and increased health care utilization.

Extracephalic Yawning Pain

The aim of this study was to report on two patients with recurrent, paroxysmal, extracephalic pain triggered by yawning. Pain with yawning may occur in several conditions (secondary yawning pain) or develop in the absence of precipitating lesions (primary yawning pain). Primary yawning pain is normally of cephalic location. Methods used were clinical neurological examinations, magnetic resonance imaging of the brain, computerized head tomography, electroencephalogram, blink reflex studies and Panorex X-ray views of the skull. The first patient had intense right shoulder pain and brief apnea for 2 years triggered by yawning. The second patient had yawning pain referred to an area of the neck where a thyroid tumour (Hürthle cell carcinoma) was later found. Neither of the two patients could precipitate their pain with imitation of yawning and neither had evidence of Eagle syndrome. Only the second patient had a history of migraine. Yawning pain may have an extratrigeminal and extracephalic distribution. It rarely serves to identify a lesion underlying the area where the pain is perceived.

The relationships between migraine, depression, anxiety, stress, and sleep disturbances

To assess the relationships between migraine, depression, anxiety, stress, and sleep problems. Psychiatric conditions and sleep disturbances are common in migraineurs. Depression, anxiety, stress, migraine, and sleep problems frequently coexist as comorbidities. Eighty-seven episodic migraineurs (62 females, 25 males; 32.8 ± 6.9) and 41 control subjects (25 females, 16 males; 31.5 ± 5.6) were prospectively enrolled for the study. The participants completed a sociodemographic data form and a migraine disability assessment scale (MIDAS), depression, anxiety, stress scale (DASS), and Pittsburg Sleep Quality Index (PSQI). In migraineurs, a significant positive correlation was found between PSQI total scores and MIDAS scores (migraine related disability for at least three consecutive months) (r = 0. 234, p = 0.04). Only 24.1 % of migraineus (n = 21) had minimal or no disability, 75.9 % of the patients (n = 66) had more than a little disability according to MIDAS scores. PSQI total scores were also correlated with pain intensity over a three month period (MIDAS B) (r = 0.221, p = 0.04). While PSQI scores were found significantly different between migraineurs and control subjects (5.5 ± 2.9 vs 4.5 ± 2.5; p = 0.04), the correlation of all the DASS subscale scores between the groups was not statistically significant. Our findings showed that episodic migraine was a risk factor on its own for sleep disturbances without comorbid depression, anxiety, and stress. Moreover, migraine-related disability and pain intensity in migraine attacks were related to poor sleep quality.

Prevalence and clinical features associated to bipolar disorder-migraine comorbidity: a systematic review

BACKGROUND

The prevalence and clinical features associated with bipolar disorders (BDs)-migraine comorbidity have been reported inconsistently across different studies, therefore warranting a systematic review on the matter.

METHODS

A systematic review was conducted in accordance with the PRISMA statement searching major electronic databases for documents indexed between January, 2000 and July, 2014. Eligible studies were those including quantitative data on prevalence rates and clinical features associated to BD-migraine comorbidity; case reports excluded. Three authors independently conducted searches, quality assessment of the studies and data extraction.

RESULTS

Several cross-sectional studies, and a handful of retrospective follow-up studies or non-systematic reviews assessed the prevalence and/or the clinical correlates of migraine-BD comorbidity. High prevalence rates and a significant burden of BD-migraine comorbidity were common findings, particularly in case of BD-II women (point-prevalence rates up to 77%), migraine with aura (up to 53%) and/or cyclothymic temperament (up to 45% of the cases).

LIMITATIONS

Some of the biases encountered in a few studies accounted by the present review may nonetheless have hampered the generalizability of the overall conclusions drawn herein.

CONCLUSIONS

BD-migraine comorbidity may comprise of a sub-phenotype of BDs requiring patient-tailored therapeutic interventions to achieve an optimal outcome. Specifically, additional studies including longitudinal follow-up studies are aimed in order to shed further light on the actual prevalence rates and clinical features associated to BD-migraine comorbidity, with a special emphasis towards the clinically suggestive potential connection between mixed features, bipolar depression, migraine, and increased risk for suicidality. PROSPERO registration number: CRD42014009335.

Higher prevalence of migraine in essential tremor: a case-control study

BACKGROUND

The existence of an association between migraine and essential tremor has long been controversial. The prevalence of migraine in essential tremor patients was surveyed to explore the association between the two diseases.

METHODS

A case-control clinical study was conducted to investigate the prevalence of migraine in 150 consecutive essential tremor patients and in 150 matched controls without tremor. Detailed information about essential tremor and migraine was obtained using a structured questionnaire at a face-to-face interview. Moreover, a functional variant of the dopamine receptor D3 gene (Ser9Gly, rs6280) was studied in 46 essential tremor patients with and without migraine using direct sequencing analysis.

RESULTS

The prevalence of lifetime migraine in essential tremor patients was significantly higher than that in controls (22.0% vs. 12.7%; p=0.035; odds ratio=1.95; 95% confidence interval=1.05-3.60). No significant difference was found in the migraine features between the essential tremor and control groups and most tremor characteristics were no different in essential tremor patients with and without migraine. A higher male prevalence of essential tremor patients without migraine was observed. Moreover, 44 of 46 (95.7%) essential tremor patients had the dopamine receptor D3 Ser9Gly variant, but no significant difference was found in the frequencies of the variant between essential tremor patients with and without migraine (87.5% vs. 100.0%; p=0.22).

CONCLUSION

Our data suggest that essential tremor patients have a higher risk of lifetime migraine than do controls and the dopamine receptor D3 Ser9Gly variant may be lower in essential tremor with migraine than the general essential tremor patients.

Headache in chronic cocaine users: A cross-sectional study

Background

Headache is one of the most common symptoms after cocaine use.

Methods

We investigated headache frequency and characteristics and the correlation between headache and acute cocaine intake in a cross-sectional study in a consecutive series of chronic cocaine users.

Results

Participation rate was 94.1%. Of the 80 subjects enrolled, 72 (90%) reported current headaches, in most cases migraine or probable migraine without aura. Of these 72, 29 (40.3%) had a headache history, whereas 43 (59.7%) reported de novo headache after beginning to use cocaine. After acute cocaine use, a large percentage of users reported headache attacks: 86.2% of previous headache sufferers (migraine or probable migraine without aura in all cases) and 93% of de novo headache sufferers (migraine/probable migraine without aura = 35; episodic tension-type headache = three patients; cocaine-induced headache= two patients). Most subjects reported that when they used cocaine headaches worsened.

Conclusion

Chronic cocaine use frequently seems to worsen or induce headache with migraine or migraine-like characteristics, probably owing to a serotoninergic and dopaminergic system impairment. In headache sufferers, especially those with migraine headaches, clinicians should enquire into possible cocaine use.

Dopaminergic symptoms in migraine

Migraine pain is often preceded, accompanied and followed by dopaminergic symptoms (premonitory yawning and somnolence, accompanying nausea and vomiting, postdromal somnolence, euphoria and polyuria). After reviewing evidence from pharmacological, biochemical, genetic and animal experimental studies on the relationship between dopamine and migraine, and matching these data with patients' clinical features, we postulate that migraine attacks could be characterized by an ictal dopamine release in a subject with dopamine receptor hypersensitivity due to a chronic dopaminergic deficit synergistic to serotoninergic impairment. Our review suggests that when the attack begins, a low dopamine plasma concentration stimulates hypersensitive central presynaptic dopamine receptors thus causing prodromal symptoms such as yawning and somnolence. Increasing dopamine levels, though still insufficient to stop trigeminovascular activation, stimulate postsynaptic dopamine receptors thus inducing nausea, vomiting and hypotension. Finally, dopamine levels slowly return to baseline, giving rise to somnolence and fatigue, but, in some cases, continue to rise triggering postdromal symptoms such as euphoria and polyuria.

Recent progress in migraine pathophysiology: role of cortical spreading depression and magnetic resonance imaging

Migraine is characterised by debilitating pain, which affects the quality of life in affected patients in both the western and the eastern worlds. The purpose of this article is to give a detailed outline of the pathophysiology of migraine pain, which is one of the most confounding pathologies among pain disorders in clinical conditions. We critically evaluate the scientific basis of various theories concerning migraine pathophysiology, and draw insights from brain imaging approaches that have unraveled the prevalence of cortical spreading depression (CSD) in migraine. The findings supporting the role of CSD as a physiological substrate in clinical pain are discussed. We also give an exhaustive overview of brain imaging approaches that have been employed to solve the genesis of migraine pain, and its possible links to the brainstem, the neocortex, genetic endophenotypes, and pathogenetic factors (such as dopaminergic hypersensitivity). Furthermore, a roadmap is proposed to provide a better understanding of pain pathophysiology in migraine, to enable the development of strategies using leads from brain imaging studies for the identification of early biomarkers, efficient prognosis, and treatment planning, which eventually may help in alleviating some of the devastating impact of pain morbidity in patients afflicted with migraine.

Studies on the pathophysiology and genetic basis of migraine

Migraine is a neurological disorder that affects the central nervous system causing painful attacks of headache. A genetic vulnerability and exposure to environmental triggers can influence the migraine phenotype. Migraine interferes in many facets of people's daily life including employment commitments and their ability to look after their families resulting in a reduced quality of life. Identification of the biological processes that underlie this relatively common affliction has been difficult because migraine does not have any clearly identifiable pathology or structural lesion detectable by current medical technology. Theories to explain the symptoms of migraine have focused on the physiological mechanisms involved in the various phases of headache and include the vascular and neurogenic theories. In relation to migraine pathophysiology the trigeminovascular system and cortical spreading depression have also been implicated with supporting evidence from imaging studies and animal models. The objective of current research is to better understand the pathways and mechanisms involved in causing pain and headache to be able to target interventions. The genetic component of migraine has been teased apart using linkage studies and both candidate gene and genome-wide association studies, in family and case-control cohorts. Genomic regions that increase individual risk to migraine have been identified in neurological, vascular and hormonal pathways. This review discusses knowledge of the pathophysiology and genetic basis of migraine with the latest scientific evidence from genetic studies.

Emerging genomic biomarkers in migraine

Migraine is a debilitating neurovascular condition classified as either migraine with aura or migraine without aura. A significant genetic basis has been implicated in migraine and has probed the role of neurotransmitters, hormones and vascular genes in this disorder. The aim of this review is to highlight the recent genetic discoveries contributing to our understanding of the complex pathogenesis of migraine. The current review will discuss the role of neurotransmitter-related genes in migraine, including the recently identified TRESK and variants of the KCNN3 gene, as well as outlining studies investigating hormone receptor genes, such as ESR1 and PGR, and vascular-related genes, including the MTHFR and NOTCH 3 genes.

Self-regulation therapy to reproduce drug effects: a suggestion technique to change personality and the DRD3 gene expression

This study proposes a strategy, based on self-regulation therapy, to change personality and its biological substrate, the DRD3 gene expression. It has been demonstrated that acute doses of stimulating drugs, like methylphenidate, are able to change personality and the expression of certain genes in the short term. On the other hand, self-regulation therapy has been proven to reproduce the effects of drugs. Thus, it is feasible to hope that self-regulation therapy is equally effective as methylphenidate in changing personality and the gene expression. This is a preliminary study with a single-case experimental design with replication in which 2 subjects participated. The results and potential implications for research and psychotherapy are discussed.

Psychiatric comorbidities of episodic and chronic migraine

Migraine is a prevalent disabling neurological disorder associated with a wide range of medical and psychiatric comorbidities. Population- and clinic-based studies suggest that psychiatric comorbidities, particularly mood and anxiety disorders, are more common among persons with chronic migraine than among those with episodic migraine. Additional studies suggest that psychiatric comorbidities may be a risk factor for migraine chronification (i.e., progression from episodic to chronic migraine). It is important to identify and appropriately treat comorbid psychiatric conditions in persons with migraine, as these conditions may contribute to increased migraine-related disability and impact, diminished health-related quality of life, and poor treatment outcomes. Here, we review the current literature on the rates of several psychiatric comorbidities, including depression, anxiety, and post-traumatic stress disorder, among persons with migraine in clinic- and population-based studies. We also review the link between physical, emotional, and substance abuse, psychiatric disorders, and migraine. Finally, we review the data on psychiatric risk factors for migraine chronification and explore theories and evidence underlying the comorbidity between migraine and these psychiatric disorders.

The dopaminergic system in peripheral blood lymphocytes: from physiology to pharmacology and potential applications to neuropsychiatric disorders

Besides its action on the nervous system, dopamine (DA) plays a role on neural-immune interactions. Here we review the current evidence on the dopaminergic system in human peripheral blood lymphocytes (PBL). PBL synthesize DA through the tyrosine-hydroxylase/DOPA-decarboxylase pathway, and express DA receptors and DA transporter (DAT) on their plasma membrane. Stimulation of DA receptors on PBL membrane contributes to modulate the development and initiation of immune responses under physiological conditions and in immune system pathologies such as autoimmunity or immunodeficiency.

The characterization of DA system in PBL gave rise to a further line of research investigating the feasibility of PBL as a cellular model for studying DA derangement in neuropsychiatric disorders. Several reports showed changes of the expression of DAT and/or DA receptors in PBL from patients suffering from several neuropsychiatric disorders, in particular parkinsonian syndromes, schizophrenia and drug- or alcohol-abuse. Despite some methodological and theoretical limitations, these findings suggest that PBL may prove a cellular tool with which to identify the derangement of DA transmission in neuropsychiatric diseases, as well as to monitor the effects of pharmacological treatments.

Dopamine D1-like receptor antagonist attenuates Th17-mediated immune response and ovalbumin antigen-induced neutrophilic airway inflammation

Allergic airway inflammation is generally considered a Th2-type immune response. Recent studies, however, demonstrated that Th17-type immune responses also play important roles in this process, especially in the pathogenesis of neutrophilic airway inflammation, a hallmark of severe asthma. We previously reported that dendritic cells release dopamine to naive CD4(+) T cells in Ag-specific cell-cell interaction, in turn inducing Th17 differentiation through dopamine D1-like receptor (D1-like-R). D1-like-R antagonist attenuates Th17-mediated diseases such as experimental autoimmune encephalomyelitis and autoimmune diabetes. However, the effect of antagonizing D1-like-R on Th17-mediated airway inflammation has yet to be studied. In this study, we examined whether D1-like-R antagonist suppresses OVA-induced neutrophilic airway inflammation in OVA TCR-transgenic DO11.10 mice and then elucidated the mechanism of action. DO11.10 mice were nebulized with OVA or PBS, and some mice received D1-like-R antagonist orally before OVA nebulization. D1-like-R antagonist significantly suppressed OVA-induced neutrophilic airway inflammation in DO11.10 mice. It also inhibited the production of IL-17 and infiltration of Th17 cells in the lung. Further, D1-like-R antagonist suppressed the production of IL-23 by lung CD11c(+) APCs. In contrast, D1-like-R antagonist did not increase Foxp3(+) regulatory T cells in the lung. D1-like-R antagonist neither suppressed nonspecific LPS-induced neutrophilic airway inflammation nor OVA-induced eosinophilic airway inflammation. These results indicate that D1-like-R antagonist could suppress Th17-mediated neutrophilic airway inflammation, raising the possibility that antagonizing D1-like-R serves as a promising new strategy for treating neutrophil-dominant severe asthma.

Is the dopamine D3 receptor mRNA on blood lymphocytes help to for identification and subtyping of schizophrenia?

Schizophrenia is one of the neuropathological disorders, which are associated with dopamine and its receptors. In recent years, it has been shown that mRNA of D3, D4 and D5 dopamine receptor (DRD3, DRD4, DRD5) subtypes is expressed in human peripheral blood lymphocytes (PBL). A total 55 schizophrenic patients and 51 healthy subjects were included in the study to investigate the levels of DRD3 mRNA in PBL of schizophrenic patients and whether DRD3 mRNA level in PBL can serve as peripheral marker for schizophrenia. RNA was isolated from lymphocytes of both groups and reverse transcriptase polymerase chain reaction (RT-PCR) was performed for DRD3 mRNA. We found a significant difference in PBL DRD3 mRNA levels among schizophrenia subtypes (P=0.030) while no difference was detected between control subjects and schizophrenics. We concluded that the levels of DRD3 mRNA can help understanding and severity of clinical manifestations in schizophrenia.

Platelet Dopamine: D2 Receptor Binding in Patients with Migraine

Clinical, genetic and pharmacological evidences suggest an abnormality of the dopaminergic system in the pathogenesis of migraine. Direct evidence of an abnormal metabolism of dopamine in migraine, however, is lacking. Platelets are a useful model to understand brain dopaminergic mechanisms. The present study has been undertaken to study the status of platelet dopamine receptor binding by carrying out radioligand receptor binding assay. Binding of3H-spiperone to platelet membranes, known to label dopamine (DA)—D2 receptors, was conducted in 20 patients with migraine and an equal number of healthy controls. The equilibrium dissociation constant (Kd) in patients with migraine (1.71 ± 0.19 nM) was found to be significantly lower ( P < 0.001) as compared with controls (3.14 ± 0.33 nM). However, no significant change was observed in the maximal number of binding sites (Bmax) in patients with migraine. No relationship of Kd with type of migraine, presence of vomiting, family history, frequency of attack, duration of illness and menstrual migraine was observed. The findings of the present study provide support for the involvement of the dopaminergic system in migraine.

Dopamine receptors in human lymphocytes: radioligand binding and quantitative RT-PCR assays

Analysis of dopamine receptors (DR) in lymphocytes of the human peripheral blood mononuclear cell (PBMC) fraction is an attractive tool for evaluation of functional properties of dopaminergic function underlying variation in complex psychological/psychopathological traits. Receptor binding assays (RBAs) with selective radioligands, which are widely used in CNS studies, have not produced consistent results when applied to isolated PBMC. We tested the assay conditions that could be essential for detection of DR in human PBMC and their membrane preparations. Using [(3)H]SCH23390, a dopamine D1-like receptor antagonist, we demonstrated the presence of two binding sites in PBMC-derived membrane fraction. One of them is characterized by the K(d) value consistent with that reported for D5 dopamine receptors in human lymphocytes, whereas the other K(d) value possibly corresponds to serotonin receptor(s). Although D5 receptor binding sites in PBMC membranes could be characterized by binding assays, the low protein expression and the large volume of blood needed for membrane preparation render the binding method impracticable for individual phenotyping. In contrast, real-time RT-PCR may be used for this purpose, contingent on the relationship between DR expression in the brain and in lymphocytes. The expression of the DRD2-DRD5 genes, as detected by this method, varied widely among samples, whereas the DRD1 expression was not detected. The expression levels were comparable with those in the brain for DRD3 and DRD4, and were significantly lower for DRD2 and DRD5.

Current and prospective pharmacological targets in relation to antimigraine action

Migraine is a recurrent incapacitating neurovascular disorder characterized by unilateral and throbbing headaches associated with photophobia, phonophobia, nausea, and vomiting. Current specific drugs used in the acute treatment of migraine interact with vascular receptors, a fact that has raised concerns about their cardiovascular safety. In the past, alpha-adrenoceptor agonists (ergotamine, dihydroergotamine, isometheptene) were used. The last two decades have witnessed the advent of 5-HT(1B/1D) receptor agonists (sumatriptan and second-generation triptans), which have a well-established efficacy in the acute treatment of migraine. Moreover, current prophylactic treatments of migraine include 5-HT(2) receptor antagonists, Ca(2+) channel blockers, and beta-adrenoceptor antagonists. Despite the progress in migraine research and in view of its complex etiology, this disease still remains underdiagnosed, and available therapies are underused. In this review, we have discussed pharmacological targets in migraine, with special emphasis on compounds acting on 5-HT (5-HT(1-7)), adrenergic (alpha(1), alpha(2,) and beta), calcitonin gene-related peptide (CGRP(1) and CGRP(2)), adenosine (A(1), A(2), and A(3)), glutamate (NMDA, AMPA, kainate, and metabotropic), dopamine, endothelin, and female hormone (estrogen and progesterone) receptors. In addition, we have considered some other targets, including gamma-aminobutyric acid, angiotensin, bradykinin, histamine, and ionotropic receptors, in relation to antimigraine therapy. Finally, the cardiovascular safety of current and prospective antimigraine therapies is touched upon.

A dopamine D4 receptor exon 3 VNTR allele protecting against migraine without aura

OBJECTIVE

As dopamine plays an important role in the pathophysiology of migraine and antimigraine drugs have an effect on the dopamine system, the objective of this study was to examine the dopamine D4 receptor gene for involvement in the cause of migraine.

METHODS

We tested a VNTR-polymorphism in the dopamine D4 receptor gene, the exon 3 VNTR, in a sample of 190 family trios each with a proband with childhood migraine by using transmission disequilibrium test tests.

RESULTS

We found a trend for transmission distortion of this marker in migraine, with the common seven-repeat allele of the VNTR transmitted 58 times and not transmitted 82 times (global likelihood ratio score (LRS) = 12.27, degress of freedom (DF) = 6, p = 0.06; for the 7-repeat allele: chi(2) = 5.1, p = 0.02). This effect came only from migraine without aura (145 trios), with the common 7-repeat allele transmitted 45 times and not transmitted 69 times (global LRS = 15.18; DF = 6, p = 0.019; for the 7-repeat allele: chi(2) = 6.4, p = 0.01; odds ratio, 0.47), whereas in migraine with aura (45 trios) there was no transmission distortion of the 7-repeat allele.

INTERPRETATION

We conclude that seven-repeat allele of the dopamine D4 receptor VNTR is a protective factor for migraine without aura. Because migraine is a common disorder, this protective effect may have contributed to the positive selection acting on the dopamine D4 receptor exon 3 VNTR seven-repeat allele in recent human history. We speculate that dopamine function in the lateral parabrachial nucleus is involved in migraine without aura.

Association between a 19 bp deletion polymorphism at the dopamine beta-hydroxylase (DBH) locus and migraine with aura

Migraine is a debilitating neurological disorder, affecting 12% of Caucasian populations. It is well known that migraine has a strong genetic component, although the type and number of genes involved is unclear. Our previous work has investigated dopamine related migraine candidate genes and has reported a significant allelic association with migraine of a microsatellite localised to the promoter region of the dopamine beta-hydroxylase (DBH) gene. The present study performed an association analysis in a larger population of case-controls (275 unrelated Caucasian migraineurs versus 275 controls) examining two different genetic DBH polymorphisms (a functional insertion/deletion promoter and a coding SNP A444G polymorphism). Although no significant association was found for the SNP polymorphism, the results showed a significant association between the insertion/deletion variant and disease (chi(2)=8.92, P=0.011), in particular in migraine with aura (chi(2)=11.53, P=0.003) compared to the control group. Furthermore, the analysis of this polymorphism stratified by gender, revealed that male individuals with the homozygote deletion genotype had three times the risk of developing migraine, compared to females. The DBH insertion/deletion polymorphism is in linkage disequilibrium with the previously reported migraine associated DBH microsatellite and this insertion/deletion polymorphism is functional, which may explain a potential role in susceptibility to migraine.

Platelet Levels of Dopamine Are Increased in Migraine and Cluster Headache

OBJECTIVE

To measure plasma and platelet levels of dopamine in patients with migraine with aura, migraine without aura, and cluster headache.

BACKGROUND

Clinical, genetic, and pharmacological evidences suggest that an abnormality of dopaminergic system plays a role in migraine pathogenesis. Direct evidence of an abnormal metabolism of dopamine in migraine, however, is lacking.

METHODS

Plasma and platelet levels of dopamine were measured in patients with migraine with aura or migraine without aura during headache-free periods and in patients with cluster headache during the remission and active periods, as compared with healthy control subjects, using a multichannel electrochemical high-performance liquid chromatography system.

RESULTS

Plasma levels of dopamine were not detectable with our methodology. Platelet levels of dopamine were higher in both types of migraine (migraine without aura = .20 +/- .17 ng/10(8) platelets; migraine with aura = .16 +/- .19 ng/10(8) platelets) than in control subjects (.10 +/- .11 ng/10(8) platelets), although in migraine with aura patients the difference was not significant. Patients with cluster headache showed the highest levels of platelet dopamine (.34 +/- .36 ng/10(8) platelets).

CONCLUSIONS

Our results support the hypothesis that the dopaminergic system is impaired in migraine and cluster headache and suggest that high platelet levels of dopamine may represent an abnormal biochemical phenotypic trait of these primary headaches.

D3 dopamine receptor mRNA is elevated in T cells of schizophrenic patients whereas D4 dopamine receptor mRNA is reduced in CD4+ -T cells

The expression of dopamine receptors was examined in purified human neutrophils, monocytes, B cells, natural killer cells and CD4+ - and CD8+ -T lymphocytes by RT-PCR. In healthy subjects, D1 and D2 receptors were not expressed in leukocytes. Real Time PCR for dopamine receptors D3 and D4 disclosed that D3 receptors are expressed in T cells and natural killer cells and D4 receptors in CD4+ -T cells. The comparison of schizophrenic patients with sex- and age-matched controls revealed a significantly higher expression of D3 receptor mRNA in T cells of schizophrenic patients, whereas D4 receptor mRNA in CD4+ -T cells was downregulated.

Stigmatization in Alzheimer's disease research on African American elders

Stigmatization in research sustains the spread of the silent epidemic of Alzheimer's disease (AD) in African American populations. Researchers use stereotypes and inappropriate assumptions to select a paradigm to examine the symptoms of AD. This paradigm fails to encompass the symptoms as manifested by African American elders. Yet, stigmatization can be minimized by recognizing the genetic heterogeneity of the symptoms within the general population, especially those manifested by African American elders. Thus, researchers can utilize pioneering genetic analyses to identify other paradigms critical in the assessment and proactive treatment of the symptoms of AD needed for this vulnerable population.

Comorbidity of major depression and migraine--a Canadian population-based study

OBJECTIVE

To estimate the prevalence of major depressive episodes (MDEs) in patients with migraine and to compare the strength of association with that of other long-term medical conditions.

METHODS

This study used a large-scale probability sample (over 130,000 sample) from the Canadian Community Health Survey (CCHS), a cross-sectional survey conducted by Statistics Canada. The CCHS screened for a broad set of medical conditions. Major depression was evaluated with the Composite International Diagnostic Interview Short Form for Major Depression, and the diagnosis of migraine was self-reported. The annual prevalence of major depression was calculated in the general population, in subjects with migraine, and in those with chronic conditions other than migraine.

RESULTS

The prevalence of major depression in subjects reporting migraine was higher than that in the general population or in subjects with other chronic medical conditions (17.6%, compared with 7.4% and 7.8%, respectively).

CONCLUSIONS

There is a strong association between major depression and migraine. The migraine-MDE association may account for a large fraction of the chronic condition-MDE association. The association between migraines and MDE differs from that of other chronic conditions, as the association persists into older age groups.

Dopamine by itself activates either D2, D3 or D1/D5 dopaminergic receptors in normal human T-cells and triggers the selective secretion of either IL-10, TNFalpha or both

The neurotransmitter dopamine on its own increased significantly TNFalpha and IL-10 secretion by resting normal-human T-cells, and induced approximately 5-fold elevation of the corresponding mRNA's, without affecting IFNgamma and IL-4. Using seven highly selective dopamine-receptor (DR) agonists and antagonists we found that TNFalpha-upregulation, evident after 24 h, was mediated by D3R and D1/D5R while IL-10-upregulation, evident after 72 h, was mediated by D2R and D1/D5R. We confirmed the expression of D2R and D3R in these human T cells. Dopamine's unique ability to trigger a selective secretion of either TNFalpha only (via D3R) or IL-10 only (via D2R) or both (via D1/D5R), differs from the robust and non-selective cytokine-secretion induced by 'classical' TCR-activation, and as such may have important beneficial or detrimental implications in various immunological and neurological diseases/injuries/cancers.

Lack of interaction between a polymorphism in the dopamine D2 receptor gene and the clinical features of migraine

The purpose of this study was to evaluate whether a particular genotype of the dopamine D2 receptor (DRD2) gene would affect the clinical features of migraine. In a group of 118 migraineurs (55 migraine with aura and 63 migraine without aura patients), we tested the association of the biallelic C/T NcoI DRD2 polymorphism with several characteristics of the disease. Genotype and allele frequencies resulted similarly distributed in migraine with aura and migraine without aura patients (chi2 = 1.58, P = 0.45 and chi2 = 0.09, P = 0.77, respectively). The different DRD2 genotypes (C/C, C/T and T/T) had no significant effects on age at onset of migraine, presence of premonitory phenomena, frequency of headache attacks, associated symptoms, psychological features and quality of life of our migraine patients. The results of our study do not support a role for the DRD2 gene in modifying the clinical features of migraine.

Dopamine receptor D3 mRNA expression in human lymphocytes is negatively correlated with the personality trait of persistence

It has been proposed that neurotransmitter receptor expression in peripheral immune cells reflects expression of these receptors in the brain. To test this "peripheral marker hypothesis", we compared mRNA expression of the dopamine receptors D3 (DRD3) and D4 (DRD4) in peripheral blood lymphocytes (PBL) to personality traits assessed with the Temperament and Character Inventory (TCI) in 50 healthy and unmedicated Caucasian individuals. A shared variance of at least 17% (p=0.016) between DRD3 mRNA expression in PBL and the personality trait of persistence was found. As personality traits have been generally assumed polygenic with a single gene accounting for rarely more than 1-2% of observed variance in a trait, this result lends further support to the peripheral marker hypothesis for DRD3 mRNA expression in PBL. It may also suggest a significant role for the DRD3 in the neurobiology of persistence and point to an interesting link between personality and functioning of the immune system.

Aberrant A2A receptor function in peripheral blood cells in Huntington's disease

A2A adenosine receptors specifically found on striatal medium spiny neurons play a major role in sensory motor function and may also be involved in neuropsychiatric and neurodegenerative disorders. One hypothesis concerning Huntington's disease (HD) proposes that an imbalance of the cortico-striatal pathway, due to the mutation in the HD gene, leads to striatal vulnerability. An A2A receptor dysfunction has been previously demonstrated in striatal cells engineered to express mutant huntingtin. Here we tested whether a similar dysfunction (i.e., the binding and functional parameters of A2A adenosine receptors) is present in peripheral blood cells (platelets, lymphocytes, and neutrophils) of subjects carrying the mutant gene. This study involved 48 heterozygous and three homozygous patients compared with 58 healthy subjects. Moreover, we selected seven at-risk mutation carriers. A2A receptor density and function are substantially increased in peripheral blood cells from both patients and subjects at the presymptomatic stage. In the neutrophils of the three homozygous HD subjects receptor dysfunction was higher than in heterozygotes. These data indicate the existence of an aberrant A2A receptor phenotype in the peripheral blood cells of subjects carrying the HD mutation. Future studies will assess whether this parameter can be exploited as a peripheral biomarker of Huntington's disease.

Dopamine inhibits cytokine release and expression of tyrosine kinases, Lck and Fyn in activated T cells

The effect of dopamine (DA) on the release of cytokines from activated human T cells has been evaluated to analyze the mechanism by which physiological concentration of dopamine inhibits T cell proliferation. Dopamine inhibited anti-CD3 mAb-induced release of both Th1 and Th2 cytokines, IL2, IFN-gamma and IL4 from T cells by specific class of dopamine receptors. This action of dopamine was mediated by a new mechanism. Dopamine suppressed non-receptor tyrosine kinases, Lck and Fyn expression which are the initial and pivotal signaling steps in T cell receptor (TCR) mediated different down stream signaling cascades, leading to cytokine release and subsequent clonal expansion of these immune effector cells.

Molecular Mechanisms of Migraine

Migraine is a common complex disorder that affects a large portion of the population and thus incurs a substantial economic burden on society. The disorder is characterized by recurrent headaches that are unilateral and usually accompanied by nausea, vomiting, photophobia, and phonophobia. The range of clinical characteristics is broad and there is evidence of comorbidity with other neurological diseases, complicating both the diagnosis and management of the disorder. Although the class of drugs known as the triptans (serotonin 5-HT(1B/1D) agonists) has been shown to be effective in treating a significant number of patients with migraine, treatment may in the future be further enhanced by identifying drugs that selectively target molecular mechanisms causing susceptibility to the disease.Genetically, migraine is a complex familial disorder in which the severity and susceptibility of individuals is most likely governed by several genes that may be different among families. Identification of the genomic variants involved in genetic predisposition to migraine should facilitate the development of more effective diagnostic and therapeutic applications. Genetic profiling, combined with our knowledge of therapeutic response to drugs, should enable the development of specific, individually-tailored treatment.

Migraine and psychiatric comorbidity: from theory and hypotheses to clinical application

OBJECTIVE

To review psychiatric issues that accompany migraine and means of addressing these issues.

BACKGROUND

Psychiatric factors and migraine may interact in three general ways, etiologically, psychophysiologically or biobehaviorally, and comorbidly (the two disorders coexist), which is the present focus. There are several possible mechanisms of comorbidity. The relation between two disorders may be a result of chance. One disorder can cause another disorder: Diabetes can cause diabetic neuropathy. There might be shared environmental risks: Head trauma can cause both posttraumatic epilepsy and posttraumatic headache. And there may be environmental or genetic risk factors that produce a brain state giving rise to both conditions, that is, there may be some common biology underlying both conditions. This last mechanism seems to be the most likely one underlying comorbidity of migraine and psychiatric disorders. We introduce a possible role for classical paradigms of learned helplessness in regard to psychiatric comorbid depressive and anxiety disorders and migraine.

RESULTS

There appears to be an association between migraine and affective disorders, particularly depression and anxiety. There are a number of formal tools for recognizing depression, but clinical evaluation should not be overlooked. Once diagnosed, depression and anxiety should be treated, both to improve the success of migraine treatment and to improve the patient's quality of life. Patients with recurring headaches are much more likely to overuse and misuse, rather than abuse, pain medications. It is important to be alert for signs that the patient may be misusing medication. Behavioral approaches can surround and support pharmacological therapy.

CONCLUSIONS

Migraine is often comorbid with psychiatric disorders, particularly depression and anxiety. The relationship is likely based on shared mechanisms and successful treatment is possible.

Postnatal development of dopamine receptor expression in rat peripheral blood lymphocytes

Postnatal development in the expression of dopamine D1-like and D2-like receptors was investigated in peripheral blood lymphocytes of male Wistar rats aged 1, 3, 4, 8, 12 and 16 weeks of age by radioligand binding assay techniques. Sample of frontal cortex, striatum and hippocampus were also investigated as reference tissues. The dopamine D1-like receptor antagonist [3H]SCH 23390 and the dopamine D2-like receptor agonist [3H]7-OH-DPAT were used as radioligands. The affinity (K(d)) of [3H]SCH 23390 or of [3H]7-OH-DPAT binding was unchanged in lymphocytes of rats of different age groups. The density (B(max)) of [3H]SCH 23390 binding sites increased from the 1st to the 3rd week of age, remained constant from the 3rd to the 8th week of age, and then increased slightly at 12 and 16 weeks of age. The B(max) value of [3H]7-OH-DPAT binding to lymphocytes increased from the 1st to the 3rd week of age, remained constant from the 3rd to the 4th week, increased again until the 12th week and then plateaued. Dopamine D1-like and D2-like receptor maturation in frontal cortex, hippocampus and striatum revealed an increased receptor density until the 4th week of age and a relative stabilization of receptor density values between the 4th to the 12th week depending on the area considered. Comparatively postnatal maturation of lymphocyte dopamine D1-like receptors displayed a pattern different from that of brain areas investigated, whereas maturation of D2-like receptors displayed a pattern similar to that of striatum. The quantitative and/or qualitative dissimilarities between development of lymphocyte and brain dopamine receptors suggest that from a developmental point of view lymphocyte dopamine receptors probably cannot be considered as a marker of homologous brain receptors.

Migraine and the extrapyramidal system

This review explores a large series of observations from clinical and experimental studies on the interactions between migraine and the extrapyramidal system (EPS). A critical appraisal of these data suggests that the EPS is somehow involved in migraine. However, primary involvement of the EPS in the pathophysiology of migraine, as hinted at by the apparent concomitance of migraine, extrapyramidal symptoms and diseases, as well as by the common involvement of neurotransmitters and pathways, cannot as yet be proven. On the other hand, the involvement of EPS in migraine may reflect its more general role in the processing of nociceptive information and/or may be part of the complex behavioural adaptive response that characterizes migraine.

Dopamine interacts directly with its D3 and D2 receptors on normal human T cells, and activates beta1 integrin function

Dopamine by itself has not up to now been reported to activate T cell function. We show here that dopamine interacts directly with dopaminergic receptors on normal human T cells and triggers beta1 integrin-mediated T cell adhesion to a major extracellular matrix component, fibronectin (FN). Such adhesion is a characteristic feature of activated T cells, and is critical for trafficking and extravasation of T cells across blood vessels and tissue barriers. Seven dopamine D2/D3 receptor agonists and antagonists were used to identify the receptor subtypes with which dopamine specifically interacts to activate T cells. The D3 dopamine receptor agonist, 7-hydroxy-DPAT (DPAT), mimics the effects of dopamine, and the effects of both dopamine and DPAT are blocked by a specific D3 receptor antagonist, U-maleate. The dopamine receptor agonists bromocriptine and pergolide mimic the direct effect of dopamine on the beta1 integrin function, while the dopamine receptor antagonists butaclamol and haloperidol suppress it, suggesting additional signaling via the dopamine D2 receptor subtype. Our study shows, for the first time, that dopamine can directly activate T cells via ist specific receptors and suggests a possible role for dopamine in integrin-mediated cellular trafficking and extravasation of T cells in the central nervous system and possibly also in the periphery. Finally, we suggest that the reported changes in the D3 and D2 receptor RNA levels in peripheral blood lymphocytes of individuals with schizophrenia, Parkinson's disease, Alzheimer's disease and migraine can serve not only as a 'passive' diagnostic marker, but primarily reflect the dynamic functional dopamine-T cell interactions in these diseases.

Significance of the catechol-O-methyltransferase gene polymorphism in migraine

The objective was to assess the significance of the catechol-o-methyltransferase (COMT) enzyme polymorphism in migraine. For this reason, 62 migraineurs and 64 healthy volunteers were included in the study. The analysis of COMT polymorphism was performed using PCR. The H/H genotype was more frequent in the control group than in the patients group (P=0.032). The homozygous or heterozygous L allele was over represented in the migraineurs compared with the controls (P=0.013). The L/L genotype was over represented in the migraineurs who also had a family history of migraine (P=0.003). There was no relationship between aura and COMT genotypes. In conclusion, the COMT polymorphism may be of potential pharmacological importance regarding the individual differences in the metabolism of catechol drugs in migraineurs. Although altered catecholamine activity due to polymorphism of COMT gene may be one of the mechanisms involved in the pathogenesis of migraine, these mechanisms are not related to presence or absence of aura.