Calcitonin gene-related peptide (CGRP) is a key mediator in primary headaches including migraine. Animal models of meningeal nociception demonstrate both peripheral and central CGRP effects; however, the target structures remain unclear. To study the distribution of CGRP receptors in the rat trigeminovascular system we used antibodies recognizing two components of the CGRP receptor, the calcitonin receptor-like receptor (CLR) and the receptor activity-modifying protein 1 (RAMP1). In the cranial dura mater, CLR and RAMP1 immunoreactivity (-ir) was found within arterial blood vessels, mononuclear cells, and Schwann cells, but not sensory axons. In the trigeminal ganglion, besides Schwann and satellite cells, CLR- and RAMP1-ir was found in subpopulations of CGRP-ir neurons where colocalization of CGRP- and RAMP1-ir was very rare ( approximately 0.6%). CLR- and RAMP1-ir was present on central, but not peripheral, axons. In the spinal trigeminal nucleus, CLR- and RAMP1-ir was localized to "glomerular structures," partly colocalized with CGRP-ir. However, CLR- and RAMP1-ir was lacking in central glia and neuronal cell bodies. We conclude that CGRP receptors are associated with structural targets of known CGRP effects (vasodilation, mast cell degranulation) and targets of unknown function (Schwann cells). In the spinal trigeminal nucleus, CGRP receptors are probably located on neuronal processes, including primary afferent endings, suggesting involvement in presynaptic regulation of nociceptive transmission. Thus, in the trigeminovascular system CGRP receptor localization suggests multiple targets for CGRP in the pathogenesis of primary headaches.

Dumping syndrome is a frequent complication of cancer and non-cancer oesophageal and gastric surgery, as well as bariatric surgery (also known as metabolic surgery). These interventions change gastric anatomy and innervation, which can enable a considerable amount of undigested food to reach the small intestine too rapidly 1-4. Dumping syndrome comprises a constellation of symptoms that can be subdivided into early and late dumping syndrome symptoms, which can occur jointly or separately 1-8. Typically, symptoms of early dumping syndrome occur within the first hour after a meal and include gastrointestinal symptoms (abdominal pain, bloating, borborygmi, nausea and diarrhoea) and vasomotor symptoms (flushing, palpitations, perspiration, tachycardia, hypotension, fatigue, desire to lie down and, rarely, syncope) 1,2. The underlying mechanisms might involve osmotic effects, peptide hormone release and autonomic neural responses 1. Symptoms of late dumping syndrome usually occur between 1 and 3 h after a meal and are primarily the manifestations of hypoglycaemia, which mainly results from an incretin-driven hyperinsulinaemic response after carbohydrate ingestion. Hypoglycaemia-related symptoms are attributable to neuroglycopenia (which is indicated by fatigue, weakness, confusion, hunger and syncope) and to vagal and sympathetic activation (indicated by perspiration, palpitations, tremor and irritability) 1,2. The literature has referred to late dumping syndrome as 'reactive hypoglycaemia' or, after bariatric surgery, as 'postbariatric hypoglycaemia'. However, on the basis of a common pathophysiology of rapid exposure of the small intestine to nutrients, which is also seen in early dumping syndrome (see subsequent discussion), we refer to this phenomenon as 'late dumping syndrome'. The prevalence of dumping syndrome depends on the type and extent of surgery, and on the criteria used to diagnose dumping syndrome. Dumping syndrome occurs in approximately 20% of patients undergoing

CGRP meets its receptor in the rat dura mater. The CGRP receptor protein CLR (green) is expressed in smooth muscle cells (blue, SMA) in the media of meningeal arteries (left) but not in veins (right upper half). CLR is also found in trigeminal nerve bundles and mononuclear cells adjacent to the arteries. CGRP‐receptor components are however not co‐localized with axonal CGRP (red) in the dura, but expressed in Schwann cells (not visible at this magnification). J. Comp. Neurol. 507:1279–1301, 2008. © 2008 Wiley‐Liss, Inc.

The response to any of these conditions can, variably and unpredictably, cause hemorrhagic gastric stress erosions, nonocclusive mesenteric ischemia of the small bowel, ischemic colitis, ischemic hepatitis, acalculous cholecystitis, and/or ischemic pancreatitis. Injury to the mesenteric organs can also initiate the systemic inflammatory response syndrome and, consequently, multiple organ failure.