In order to understand the nature of the relationship between cerebral blood flow (CBF) and primary headaches, we have conducted a literature review with particular emphasis on the role of perivascular neurotransmitters. Primary headaches are in general considered complex polygenic disorders (genetic and environmental influence) with pathophysiological neurovascular alterations. Identified candidate headache genes are associated with neuro- and gliogenesis, vascular development and diseases, and regulation of vascular tone. These findings support a role for the vasculature in primary headache disorders. Moreover, neuronal hyperexcitability and other abnormalities have been observed in primary headaches and related to changes in hemodynamic factors. In particular, this relates to migraine aura and spreading depression. During headache attacks, ganglia such as trigeminal and sphenopalatine (located outside the blood-brain barrier) are variably activated and sensitized which gives rise to vasoactive neurotransmitter release. Sympathetic, parasympathetic and sensory nerves to the cerebral vasculature are activated. During migraine attacks, altered CBF has been observed in brain regions such as the somatosensory cortex, brainstem and thalamus. In regulation of CBF, the individual roles of neurotransmitters are partly known, but much needs to be unraveled with respect to headache disorders.

Objective.-The aim of this systematic review and meta-analysis (SR-MA) was to identify signaling molecule profiles and blood-derived biomarkers in migraine and cluster headache (CH) patients.Background.-Currently no migraine and CH valid biomarkers are available. Blood tests based on biomarker profiles have been used to gather information about the nervous system. Such tests have not yet been established within the primary headache field.Methods.-Case-control and case-crossover studies investigating whole blood, plasma, and serum were identified worldwide. The qualitative synthesis focused on 9 signaling molecules (serotonin [5-HT], calcitonin gene-related peptide [CGRP], endothelin-1 [ET-1], neurokinin A, neurokinin B, neuropeptide Y, pituitary adenylate cyclase-activating peptide 38 [PACAP-38], substance P (SP), and vasoactive intestinal peptide) and the quantitative synthesis on 5-HT and CGRP (≥5 comparisons available). The meta-analysis was conducted using standard and 3-level random effect models.Results.-Fifty-four eligible studies were identified (87.0% migraine, 9.3% CH, 3.7% migraine, and CH), and 2768 headache patients and 1165 controls included. Comparable fluctuations of 5-HT, CGRP, ET-1, PACAP-38, and SP in blood were generally observed between migraine and CH. Significant findings were observed for some subgroups and strata, for example, higher interictal and ictal 5-HT venous blood levels (ratio of means = 1.32, 95% CI: 1.08; 1.61; ratio of means = 1.23, 95% CI: 1.01; 1.49) in episodic migraine with aura with a female-dominated case group, higher interictal CGRP blood levels in episodic migraine (ratio of means = 1.63, 95% CI: 1.18; 2.26), and chronic migraine (ratio of means = 1.89, 95% CI: 1.33; 2.68), and higher ictal CGRP blood levels (ratio of means = 1.35, 95% CI: 1.09; 1.68) in episodic migraine were observed. In most subgroups, the quantitative synthesis revealed a high degree of heterogeneity between studies in part explained by the blood sampling site, specimen source, blood specimen, and sex distribution. Other potential confounders were age, aura, study quality, menstrual cycle, and methodology (eg, storage temperature).Conclusions.-Potential migraine and CH signaling molecule profiles and biomarkers were revealed. Nevertheless, the high degree of heterogeneity between studies impedes identification of valid biomarkers but allowed us to assess the presence of confounders. Consideration of the potential confounders identified in this SR-MA might be of importance in the experimental planning of future studies. This consideration could be incorporated through establishment of specific guidelines. Abbreviations: 2SD 2 times standard deviation, 5-HIAA 5-hydroxyindoleacetic acid, 5-HT serotonin, 5-HT 1B/1D serotonin receptor 1B/1D, CC, column chromatography, CC-RIA column chromatography and radioimmunoassay, CGRP calcitonin gene-related peptide, CH cluster headache, CI confidence interval, CSF cerebrospinal fluid, CTRL controls, CV coefficient of variation, D Cook's distance, EIA enzyme immun...

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BackgroundMigraine and Cluster Headache (CH) are two primary headaches with severe disease burden. The disease expression and the mechanisms involved are poorly known. In some attacks of migraine and in most attacks of CH, there is a release of vasoactive intestinal peptide (VIP) originating from parasympathetic cranial ganglia such as the sphenopalatine ganglion (SPG). Patients suffering from these diseases are often deprived of effective drugs. The aim of the study was to examine the localization of the botulinum toxin receptor element synaptic vesicle glycoprotein 2A (SV-2A) and the vesicular docking protein synaptosomal-associated protein 25 (SNAP25) in human and rat SPG. Additionally the expression of the neurotransmitters pituitary adenylate cyclase activating polypeptide (PACAP-38), nitric oxide synthase (nNOS), VIP and 5-hydroxttryptamine subtype receptors (5-HT1B,1D,1F) were examined.MethodsSPG from adult male rats and from humans, the later removed at autopsy, were prepared for immunohistochemistry using specific antibodies against neurotransmitters, 5-HT1B,1D,1F receptors, and botulinum toxin receptor elements.ResultsWe found that the selected neurotransmitters and 5-HT receptors were expressed in rat and human SPG. In addition, we found SV2-A and SNAP25 expression in both rat and human SPG. We report that all three 5-HT receptors studied occur in neurons and satellite glial cells (SGCs) of the SPG. 5-HT1B receptors were in addition found in the walls of intraganglionic blood vessels.ConclusionsRecent focus on the SPG has emphasized the role of parasympathetic mechanisms in the pathophysiology of mainly CH. The development of next generation’s drugs and treatment of cranial parasympathetic symptoms, mediated through the SPG, can be modulated by treatment with BoNT-A and 5-HT receptor agonists.

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Hypertension is a hemodynamic disorder and one of the most important and well-established risk factors for vascular diseases such as stroke. Blood vessels exposed to chronic shear stress develop structural changes and remodeling of the vascular wall through many complex mechanisms. However, the molecular mechanisms involved are not fully understood. Hypertension-susceptible genes may provide a novel insight into potential molecular mechanisms of hypertension and secondary complications associated with hypertension. The aim of this exploratory study was to identify gene expression differences in the middle cerebral arteries between 12-week-old male spontaneously hypertensive rats and their normotensive Wistar-Kyoto rats using an Affymetrix whole-transcriptome expression profiling. Quantitative PCR and western blotting were used to verify genes of interest. 169 genes were differentially expressed in the middle cerebral arteries from hypertensive compared to normotensive rats. The gene expression of 72 genes was decreased and the gene expression of 97 genes was increased. The following genes with a fold difference ≥1.40 were verified by quantitative PCR; Postn, Olr1, Fas, Vldlr, Mmp2, Timp1, Serpine1, Mmp11, Cd34, Ptgs1 and Ptgs2. The gene expression of Postn, Olr1, Fas, Vldlr, Mmp2, Timp1 and Serpine1 and the protein expression of LOX1 (also known as OLR1) were significantly increased in the middle cerebral arteries from spontaneously hypertensive rats compared to Wistar-Kyoto rats. In conclusion, the identified genes in the middle cerebral arteries from spontaneously hypertensive rats could be possible mediators of the vascular changes and secondary complications associated with hypertension. This study supports the selection of key genes to investigate in the future research of hypertension-induced end-organ damage.

Within‐ and between‐study heterogeneity impede identification of valid primary headache biomarkers. Homogenous subgroup identification and investigation of differential biochemical profiles and networks within and across headache categories, based on statistical techniques, might promote biomarker discovery. When studying common primary headaches with a multifactorial etiology, variability might be captured at different levels (eg, genetics, clinical features, comorbidities, triggers). Moreover, focus on biochemical profiles instead of single compounds is crucial to develop strategies for accurate differential diagnosis.

We have established a pig resource population specifically designed to elucidate the genetics involved in development of obesity and obesity related co-morbidities by crossing the obesity prone Göttingen Minipig breed with two lean production pig breeds. In this study we have performed genome wide association (GWA) to identify loci with effect on blood lipid levels. The most significantly associated single nucleotide polymorphisms (SNPs) were used for linkage disequilibrium (LD) and haplotype analyses. Three separate haploblocks which influence the ratio between high density lipoprotein cholesterol and total cholesterol (HDL-C/CT), triglycerides (TG) and low density lipoprotein cholesterol (LDL-C) levels respectively were identified on Sus Scrofa chromosome 3 (SSC3). Large additive genetic effects were found for the HDL-C/CT and LDL-C haplotypes. Haplotypes segregating from Göttingen Minipigs were shown to impose a positive effect on blood lipid levels. Thus, the genetic profile of the Göttingen Minipig breed seems to support a phenotype comparable to the metabolic healthy obese (MHO) phenotype in humans.