A double-blind placebo-controlled study of buspirone-stimulated prolactin release in non-ulcer dyspepsia--are central serotoninergic responses enhanced?

Effects of Low-Dose Amitriptyline on Epigastric Pain Syndrome in Functional Dyspepsia Patients

AIM

To observe the therapeutic effect of low-dose amitriptyline (AMT) on epigastric pain syndrome (EPS) in patients with functional dyspepsia.

METHODS

Sixty patients with EPS were randomly divided into the following two groups for a four-week clinical trial: routine treatment with pantoprazole (RT group) and the AMT group. The RT group was treated with 40 mg of pantoprazole once daily. The AMT group received 25 mg of AMT once daily before bedtime. The Nepean Dyspepsia Index (NDI) checklist, Hamilton Rating Scale of Anxiety/Depression (HAMA/HAMD), and Pittsburgh Sleep Quality Index (PSQI) were employed to evaluate dyspepsia symptoms, psychological distress, and sleep, respectively.

RESULTS

All items were similar between the two groups before treatment (0 week). After 4 weeks of treatment, the NDI-symptom checklist score as well as the severity and bothersomeness of EPS in the AMT group was significantly decreased compared with those in the RT group (p < 0.05). However, no differences were found in the frequency of NDI checklist, psychological status (HAMD/HAMA scores) of EPS, or sleep quality (PSQI score) between the two groups after treatment. In addition, the time to fall asleep was shorter in the AMT group compared with the RT group after 4 weeks of treatment (p < 0.05).

CONCLUSION

Low-dose AMT effectively improved the dyspepsia symptoms and the time to fall asleep in the EPS patients, compared with pantoprazole, although it did not reduce the psychological distress. Therefore, AMT could be considered as a good candidate for EPS treatment in the clinic.

Status of Brain Imaging in Gastroparesis

The pathophysiology of nausea and vomiting in gastroparesis is complicated and multifaceted involving the collaboration of both the peripheral and central nervous systems. Most treatment strategies and studies performed in gastroparesis have focused largely on the peripheral effects of this disease, while our understanding of the central nervous system mechanisms of nausea in this entity is still evolving. The ability to view the brain with different neuroimaging techniques has enabled significant advances in our understanding of the central emetic reflex response. However, not enough studies have been performed to further explore the brain–gut mechanisms involved in nausea and vomiting in patients with gastroparesis. The purpose of this review article is to assess the current status of brain imaging and summarize the theories about our present understanding on the central mechanisms involved in nausea and vomiting (N/V) in patients with gastroparesis. Gaining a better understanding of the complex brain circuits involved in the pathogenesis of gastroparesis will allow for the development of better antiemetic prophylactic and treatment strategies.

Empirically Supported Use of Psychiatric Medications in Adolescents and Adults with IBD

BACKGROUND

The use of psychotropic medications, particularly antidepressants, is common in patients with inflammatory bowel disease (IBD) in spite of a lack of their robust efficacy in this population. This review provides an overview of the use trends of different classes of antidepressant and anti-anxiety medication and their effects on mood, nervous system function, gastrointestinal physiology and immunity drawing from the literature available in the general population, other medical conditions, and when available, patients with IBD. It also covers the evidence base for the actions, efficacy, and potential complications of antidepressants organized by different classes.

METHODS

We conducted a PubMed search of articles relating the different drug classes probed to the terms above in different populations of interest. All types of articles were accepted including case reports and series, open and randomized trials, reviews, and expert opinion. We also examined the reference lists of the publications found.

RESULTS

Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) are the most commonly prescribed agents for anxiety and depression in patients with IBD, though their efficacy for these conditions in the general population are mild to moderate at best. SSRIs are generally well tolerated, though at higher doses, they, like most antidepressant classes, can be associated with activation, serotonergic syndrome, and increased suicidal ideation. TCAs have many more serious side effects but have some shown efficacy for functional GI symptoms. A newer class, the serotonin noradrenergic reuptake inhibitors (SNRIs), can be effective for refractory depression, anxiety and chronic pain syndromes with a side effect profile similar to both SSRIs and more mild manifestations of TCAs. Mirtazapine has moderate efficacy for depression if sedation and weight gain side effects are tolerated and some small support for use in nausea and vomiting. Bupropion targets dopamine and noradrenaline reuptake and has moderate efficacy for depression, and some small support for use in fatigue and smoking cessation. Buspirone has an indication for generalized anxiety disorder though studies show only a minimal benefit. It has some growing evidence for use in functional dyspepsia. Most of these agents have physiological effects on the brain, immune system, and gastrointestinal tract (with the exception of bupropion) hence their therapeutic and side effects manifested in these systems.

CONCLUSION

Antidepressant medications are frequently prescribed for depression, anxiety disorders, and chronic pain syndromes, but overall support for their efficacy is modest at best. Psychological interventions have growing support for having much more robust effects without the side effects of antidepressants and should be considered first-line treatment or at least an adjunct to psychotropic medications for these conditions.

Medical treatment of functional dyspepsia

Functional dyspepsia (FD) is a condition in which upper abdominal symptoms, such as epigastralgia, postprandial discomfort, and bloating, occur in the absence of any organic or metabolic disease that could explain the symptoms. The prevalence of FD is increasing, presumably because of an increasingly stressful environment, as well as overlap with other motility disorders such as gastroesophageal reflux diseases and irritable bowel syndrome. Numerous studies have attempted to determine the pathophysiological mechanisms of FD and establish effective FD treatment, with little success. Several therapeutic options have been explored, including Helicobacter pylori eradication, proton pump inhibitors, prokinetic agents, anti-depressant and anxiolytic agents, and acotiamide, a recent emerging drug. Through the many trials evaluating the efficacy of drugs for FD treatment, we found that it is necessary to treat according to the symptoms of FD and to use a combination of therapeutic options. Additional well-designed, prospective studies are needed to confirm the management of FD.

Emerging drugs for functional dyspepsia

INTRODUCTION

Functional dyspepsia (FD) is a relatively common gastrointestinal clinical condition that remains poorly understood. Controversies remain regarding the definition, pathophysiology and optimum treatment. The current treatment of FD is limited and no established regimen is available.

AREAS COVERED

Recent advances have improved our understanding of the pathophysiology of the disease and have led to the development of newer tailored therapies. Novel agents such as the motilin receptor agonist camicinal and the muscarinic M1 and M2 receptor antagonist acotiamide appear promising; however, the need for a safe and efficacious treatment remains largely unmet. This review describes the currently available management options for FD and critically evaluates emerging therapies.

EXPERT OPINION

The optimal treatment for FD is yet to be determined. A proton pump inhibitor or a prokinetic agent constitutes primary treatment. Helicobacter pylori testing and eradication is recommended. Based on currently available data, acotiamide appears promising, particularly in postprandial distress syndrome. Further large-scale multicentered trials are required to define the duration of treatment and the side-effect profile.

Current management strategies and emerging treatments for functional dyspepsia

Functional dyspepsia refers to painful and nonpainful symptoms that are perceived to arise in the upper digestive tract but are not secondary to organic, systemic or metabolic diseases. The symptoms of this syndrome often overlap with those of GERD and IBS, making its management far from simple. If Helicobacter pylori infection is diagnosed in patients with functional dyspepsia, it should be treated. In patients with mild or intermittent symptoms, reassurance and lifestyle advice might be sufficient; in patients not responding to these measures, or in those with more severe symptoms, drug therapy should be considered. Both PPIs and prokinetics can be used in initial empirical pharmacotherapy based on symptom patterns--a PPI is more likely to be effective in the presence of retrosternal or epigastric burning or epigastric pain, whereas a prokinetic is more effective in dyspepsia with early satiation or postprandial fullness. Although combinations of PPIs and prokinetics might have additive symptomatic effects, single-drug therapy is initially preferable. Antidepressants or referral to a psychiatrist or psychotherapist can be considered in nonresponders and in those whose symptoms have a marked effect on daily functioning. Despite extensive research, functional dyspepsia treatment often remains unsatisfactory. Better characterization of dyspeptic subgroups and understanding of underlying mechanisms will enable treatment advances to be made in the future.

Investigating functional dyspepsia in Asia

The diagnosis of functional dyspepsia (FD) is challenging since it depends largely on symptoms which are often heterogeneous and overlapping. This is particularly so in Asia with many different cultures and languages. Symptom-based diagnosis of FD based on Rome III criteria has not been fully validated and it may not be suitable in some Asian populations. Clinicians often assume that investigations in FD are not rewarding and physiological tests are often not available unless in the research setting. Investigation of alarm features and role of Helicobacter pylori in FD remain controversial but experts agreed that both should be tested. Physiological tests including gastric accommodation and chemical hypersensitivity tests are underutilized in Asia and available studies were few. While experts do not recommend routine clinical use of gastric accommodation tests but they agree that these tests can be advocated if clinically indicated. Empiric therapeutic trial is not currently a diagnostic option. The pathogenesis of FD is still poorly understood and there is a substantial placebo response. As a conclusion, a diagnosis of FD is challenging especially so in the context of Asia and despite the limitations of available physiological tests experts agreed that these tests can be advocated if and when clinically indicated.

Asian consensus report on functional dyspepsia

BACKGROUND AND AIM

Environmental factors such as food, lifestyle and prevalence of Helicobacter pylori infection are widely different in Asian countries compared with the West, and physiological functions and genetic factors of Asians may also be different from those of Westerners. Establishing an Asian consensus for functional dyspepsia is crucial in order to attract attention to such data from Asian countries, to articulate the experience and views of Asian experts, and to provide a relevant guide on management of functional dyspepsia for primary care physicians working in Asia.

METHODS

Consensus team members were selected from Asian experts and consensus development was carried out by using a modified Delphi method. Consensus teams collected published papers on functional dyspepsia especially from Asia and developed candidate consensus statements based on the generated clinical questions. At the first face-to-face meeting, each statement was reviewed and e-mail voting was done twice. At the second face-to-face meeting, final voting on each statement was done using a keypad voting system. A grade of evidence and strength of recommendation were applied to each statement according to the method of the GRADE Working Group.

RESULTS

Twenty-nine consensus statements were finalized, including seven for definition and diagnosis, five for epidemiology, nine for pathophysiology, and eight for management. Algorithms for diagnosis and management of functional dyspepsia were added.

CONCLUSIONS

  This consensus developed by Asian experts shows distinctive features of functional dyspepsia in Asia and will provide a guide to the diagnosis and management of functional dyspepsia for Asian primary care physicians.

Asian consensus report on functional dyspepsia

BACKGROUND/AIMS

Environmental factors such as food, lifestyle and prevalence of Helicobacter pylori infection are widely different in Asian countries compared to the West, and physiological functions and genetic factors of Asians may also be different from those of Westerners. Establishing an Asian consensus for functional dyspepsia is crucial in order to attract attention to such data from Asian countries, to articulate the experience and views of Asian experts, and to provide a relevant guide on management of functional dyspepsia for primary care physicians working in Asia.

METHODS

Consensus team members were selected from Asian experts and consensus development was carried out using a modified Delphi method. Consensus teams collected published papers on functional dyspepsia especially from Asia and developed candidate consensus statements based on the generated clinical questions. At the first face-to-face meeting, each statement was reviewed and e-mail voting was done twice. At the second face-to-face meeting, final voting on each statement was done using keypad voting system. A grade of evidence and a strength of recommendation were applied to each statement according to the method of the GRADE Working Group.

RESULTS

Twenty-nine consensus statements were finalized, including 7 for definition and diagnosis, 5 for epidemiology, 9 for pathophysiology and 8 for management. Algorithms for diagnosis and management of functional dyspepsia were added.

CONCLUSIONS

This consensus developed by Asian experts shows distinctive features of functional dyspepsia in Asia and will provide a guide to the diagnosis and management of functional dyspepsia for Asian primary care physicians.

The dopaminergic system in patients with functional dyspepsia analysed by single photon emission computed tomography (SPECT) and an alpha-methyl-para-tyrosine (AMPT) challenge test

Purpose

Functional dyspepsia (FD) is a chronic condition characterized by upper abdominal symptoms without an identifiable cause. While the serotonergic system is thought to play a key role in the regulation of gut physiology, the role of the dopaminergic system, which is important in the regulation of visceral pain and stress, is under-studied. Therefore, this study investigated the dopaminergic system and its relationship with drinking capacity and symptoms in FD patients.

Methods

In FD patients and healthy volunteers (HV) the dopaminergic system was investigated by in-vivo assessment of central dopamine D2 receptors (D2Rs) with [¹²³I]IBZM SPECT and by an acute, but reversible, dopamine depletion alpha-methyl-para-tyrosine (AMPT) challenge test. A nutrient drink test was performed to investigate the association between maximal ingested volume, evoked symptoms, and D2Rs.

Results

The HV subjects comprised 12 women and 8 men (mean age 31 ± 3 years), and the FD patients comprised 5 women and 3 men (mean age 39 ± 5 years). The FD patients had a lower left plus right average striatal binding potential (BP_NP) for the caudate nucleus (p = 0.02), but not for putamen (p = 0.15), which in the FD patients was correlated with maximal ingested volume (r = 0.756, p = 0.03). The D2R BP_NP in the putamen was correlated with nausea (r = 0.857, p = 0.01). The acute dopamine depletion test, however, failed to reveal differences in prolactin release between the FD patients and the HV subjects.

Conclusion

These preliminary data suggest that chronic rather than acute alterations in the dopaminergic system may be involved in the pathogenesis of FD. Further studies are required to reproduce our novel findings and to evaluate to what extent the dopaminergic changes may be secondary to abnormalities in serotonergic pathways.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-011-2015-6) contains supplementary material, which is available to authorized users.

Therapeutic strategies for the treatment of dyspepsia

IMPORTANCE OF THE FIELD

Dyspeptic symptoms are highly prevalent in the population and represent a major burden for healthcare systems. The ROME III criteria address and define two separate entities of functional dyspepsia: epigastric pain syndrome and postprandial distress syndrome. The etiology of dyspeptic symptoms is heterogeneous, underlying mechanisms are poorly understood and symptomatic improvement after drug therapy is often incomplete.

AREAS COVERED IN THIS REVIEW

This review of the literature included Medline data being published in the field of functional dyspepsia and different therapies.

WHAT THE READER WILL GAIN

The reader will gain a current, unbiased understanding of the pathophysiological mechanisms underlying functional dyspepsia and of the therapeutic regimens based on randomized, controlled trials and on the meta-analyses that have been published on different therapeutic agents.

TAKE HOME MESSAGE

Before starting medical treatment, a careful physical examination should exclude 'alarm symptoms'. Laboratory data, ultrasound and endoscopy are recommended in patients older than 45 - 55 years (depending on the guidelines being used). In areas with a high prevalence of Helicobacter pylori, the initial strategy includes 'test and treat' for H. pylori in addition to empiric acid suppressive therapy. Many studies have focused on the role of gastrointestinal dysmotility and hypersensitivity for dyspepsia with inconclusive results. Further therapeutic medical strategies include prokinetics, herbal preparations and psycho-/neurotopic drugs as well as additional psycho- or hypnotherapy.

A placebo-controlled trial of the 5-HT1A agonist R-137696 on symptoms, visceral hypersensitivity and on impaired accommodation in functional dyspepsia

Acute studies suggested a therapeutic benefit for fundus-relaxing drugs in functional dyspepsia (FD) with visceral hypersensitivity (VH) to gastric distention or impaired accommodation (IA), but long-term studies are lacking. R-137696 is a serotonin-1A (5-HT(1A)) receptor agonist which relaxes the proximal stomach in man. Our aim was to investigate the influence of R-137696 on symptoms in FD with VH or IA. Randomized, double-blind, placebo-controlled, parallel group study of 4 weeks R-137696 2 mg t.i.d. in FD with VH or IA. Symptoms were assessed using the patient assessment of upper gastrointestinal symptom severity index (PAGI-SYM) total score and individual symptom subscales. Barostat studies were performed before and after 4 weeks of treatment. Fifty-three patients (33 VH and 20 IA), 18 men, mean age 40 +/- 13 years were recruited. Twenty-four received placebo and 29 received R-137696. In VH patients, both placebo and R-137696 improved total symptom scores, with a tendency for superiority of placebo (-1.12 vs-0.51, P = 0.07). Placebo was superior for the subscales of early satiety, bloating, fullness and discomfort (all P < 0.05). In IA, both placebo and R-137696 had no significant influence on total or individual symptom scores (-0.08 and -0.27). In VH, both placebo and R-137696 increased the discomfort volume, without a statistical difference between both arms (+120 and +164 mL). In IA, both placebo and R-137696 enhanced accommodation, without a statistical difference between both (+77 and +159 mL). Adverse events were similar for drug and placebo. A 4-week administration of the fundus-relaxing 5-HT(1A) agonist R-137696 failed to significantly improve symptoms, VH or gastric accommodation compared to placebo.

Influence of buspirone on gastric sensorimotor function in man

BACKGROUND

Previous studies have suggested involvement of 5HT(1) receptors in the control of gastric tone.

AIM

To study the effect of buspirone, a 5HT(1A) agonist, on gastric sensorimotor function in healthy volunteers.

METHODS

Ten healthy volunteers (six males and four females, ages 20-29 years) participated in a barostat study evaluating the influence of single oral doses of buspirone (5, 10, 20, 30 and 40 mg) on tone and sensitivity of the proximal stomach. In addition, the effect of placebo or the three lowest doses of buspirone on gastric emptying was assessed using a solid and liquid gastric emptying breath test.

RESULTS

Compared to preadministration volumes, buspirone increased proximal stomach volumes in a dose-dependent manner, with significant fundic relaxation after 30 and 40 mg doses (intra-balloon volume increases of respectively 258 +/- 80 mL and 273 +/- 49 mL, P < or = 0.05). Pressure thresholds during gastric distention were not altered, but corresponding intraballoon volumes were significantly increased after 30 and 40 mg doses (respective discomfort volumes 596 +/- 73 vs. 791 +/- 87 mL and 630 +/- 73 vs.741 +/- 60 mL, both P < 0.05). Buspirone significantly slowed solid and liquid gastric emptying at the 20-mg dose.

CONCLUSION

Buspirone dose-dependently relaxes the proximal stomach in the fasting state and decreases the gastric emptying rate in healthy volunteers.

Evidence of an enhanced central 5HT response in irritable bowel syndrome and in the rat maternal separation model

Efforts to define either a biomarker for irritable bowel syndrome (IBS) or a valid animal model have proven disappointing. The aims of this study were to determine if buspirone stimulates prolactin release through the 5-hydroxytryptamine (5HT)1a receptor and whether this response is altered in patients with IBS and in the rat maternal separation model. Buspirone (30 mg) was used to stimulate prolactin release in 40 patients with IBS and in 40 healthy controls. In study 1, 10 IBS patients and 10 controls underwent pretreatment with pindolol (5HT1a antagonist) or placebo followed by buspirone. In study 2, 30 patients with IBS and 30 healthy controls had prolactin release stimulated by buspirone. Maternally separated and nonseparated rats were also treated with buspirone and prolactin monitored. Serotonin metabolites were measured together with the expression of the 5HT1a and serotonin transporter (SERT) gene. Pindolol produced a dose-dependent decrease in the buspirone prolactin response. Patients with IBS and maternally separated rats showed an exaggerated release of prolactin in response to buspirone. In the animal model, an increased turnover of 5HT was found in the brainstem together with a trend toward increased activity of the SERT gene. In conclusion altered central serotonin responses are found in both IBS and in an animal model.

Cholecystokinin hyperresponsiveness in functional dyspepsia

Functional dyspepsia (FD) is a common disorder of yet uncertain etiology. Dyspeptic symptoms are usually meal related and suggest an association to gastrointestinal (GI) sensorimotor dysfunction. Cholecystokinin (CCK) is an established brain-gut peptide that plays an important regulatory role in gastrointestinal function. It inhibits gastric motility and emptying via a capsaicin sensitive vagal pathway. The effects on emptying are via its action on the proximal stomach and pylorus. CCK is also involved in the regulation of food intake. It is released in the gut in response to a meal and acts via vagal afferents to induce satiety. Furthermore CCK has also been shown to be involved in the pathogenesis of panic disorder, anxiety and pain. Other neurotransmitters such as serotonin and noradrenaline may be implicated with CCK in the coordination of GI activity. In addition, intravenous administration of CCK has been observed to reproduce the symptoms in FD and this effect can be blocked both by atropine and loxiglumide (CCK-A antagonist). It is possible that an altered response to CCK may be responsible for the commonly observed gastric sensorimotor dysfunction, which may then be associated with the genesis of dyspeptic symptoms.

Functional dyspepsia: Are psychosocial factors of relevance

The pathogenesis of Functional Dyspepsia (FD) remains unclear, appears diverse and is thus inadequately understood. Akin to other functional gastrointestinal disorders, research has demonstrated an association between this common diagnosis and psychosocial factors and psychiatric morbidity. Conceptualising the relevance of these factors within the syndrome of FD requires application of the biopsychosocial model of disease. Using this paradigm, dysregulation of the reciprocal communication between the brain and the gut is central to symptom generation, interpretation and exacerbation. Appreciation and understanding of the neurobiological correlates of various psychological states is also relevant. The view that psychosocial factors exert their influence in FD predominantly through motivation of health care seeking also persists. This appears too one-dimensional an assertion in light of the evidence available supporting a more intrinsic aetiological link. Evolving understanding of pathogenic mechanisms and the heterogeneous nature of the syndrome will facilitate effective management. Co-morbid psychiatric illness warrants treatment with conventional therapies. Acknowledging the relevance of psychosocial variables in FD, the degree of which is subject to variation, has implications for assessment and management. Available evidence suggests psychological therapies may benefit FD patients particularly those with chronic symptoms. The rationale for use of psychotropic medications in FD is apparent but the evidence base to support the use of antidepressant pharmacotherapy is to date limited.

Role of cholecystokinin and central serotonergic receptors in functional dyspepsia

Symptoms of functional dyspepsia are characterized by upper abdominal discomfort or pain, early satiety, postprandial fullness, bloating, nausea and vomiting. It is a chronic disorder, with symptoms more than 3 mo per year, and no evidence of organic diseases. Dysfunctional motility, altered visceral sensation, and psychosocial factors have all been identified as major pathophysiological mechanisms. It is believed that these pathophysiological mechanisms interact to produce the observed symptoms. Dyspepsia has been categorized into three subgroups based on dominant symptoms. Dysmotility-like dyspepsia describes a subgroup of patients whose symptom complex is usually related to a gastric sensorimotor dysfunction. The brain-gut peptide cholecystokinin (CCK) and serotonin (5-HT) share certain physiological effects. Both have been shown to decrease gastric emptying and affect satiety. Furthermore the CCK induced anorexia depended on serotonergic functions probably acting via central pathways. We believe that abnormalities of central serotonergic receptors functioning together with a hyper responsiveness to CCK or their interactions may be responsible for the genesis of symptoms in functional dyspepsia (FD).

Altered neuroendocrine response and gastric dysmotility in the Flinders Sensitive Line rat

In the search for animal models that can replicate some features of functional dyspepsia (FD) patients, we turned our interest to the Flinders Sensitive Line (FSL) rat. Gastric motility disturbances prevalent in FD patients as well as urine corticosterone and plasma prolactin were measured following buspirone challenge. Flinders Resistant Line (FRL) rat was used as control. The results show that the FSL rats have a disturbed gastric motility, reflected as both an increased gastric accommodation rate and gastric volume during gastric distension as well as a delayed gastric emptying, the latter possibly as a consequence of the former. Lipid administration resulted in a significant increase in maximal gastric volume only in the FRL rats. Both the corticosterone response to buspirone and the 24-h urinary output of corticosterone were normal in FSL rats. Similar to FD patients, the FSL rat showed supersensitivity to buspirone in the increase in prolactin release. Although FSL rats show some features similar to a subset of FD patients, the increased gastric accommodation contrasts to the reduced accommodation often seen in FD patients. Further studies are warranted to determine the relevance of this rat strain as a model for FD.

Differing central amine receptor sensitivity in different migraine subtypes? A neuroendocrine study using buspirone

Despite the importance of the 5HT1A receptor in regulating central serotonergic tone, there is a dearth of research examining its role in migraine. In this study, we examined the hypothesis that there would be altered neuroendocrine responses to a 5HT1A agonist challenge in different migraine subtypes. Prolactin (PRL) responses to the 5HT1A receptor agonist drug buspirone were compared in 30 female subjects with migraine (ten migraine with aura, MA; ten migraine without aura, MO and ten chronic/transformed migraine, CM), and ten healthy controls matched for age, gender and menstrual status. None of the subjects were taking psychotropic medication or migraine prophylactic treatment and those with formal psychiatric disorder were excluded. Endocrine responses were determined by measuring differences between baseline PRL and maximum increases post-buspirone (deltaPRL). There was no difference in baseline PRL between groups. MA subjects did not differ in their PRL responses to buspirone compared to healthy controls. The MO group had a four-fold increase in mean deltaPRL responses compared to healthy controls. Mean deltaPRL was also increased in the CM group compared to controls, but the difference was less exaggerated. This study indicates that there is supersensitive central amine receptor function in MO and CM, but not in MA. These findings support the hypothesis that central 5HT function differs among the migraine subtypes. The results also suggest that migrainous 'transformation' may be associated with adaptive changes in central 5HT receptor sensitivity. The relative contribution of 'state' and 'trait' receptor function to these findings as well as the possible role of dopamine receptors is discussed.

Central 5-HT receptor hypersensitivity in migraine without aura

Serotonin has long been implicated as a key neurotransmitter in migraine. There is a dearth of research specifically examining 5-HT1A receptor sensitivity in migraine despite the importance of this receptor in regulating central serotonergic tone. In this study we examined the hypothesis that migraine without aura is associated with hypersensitivity of central 5-HT1A receptors, using a 5-HT1A neuroendocrine challenge drug and comparing serum prolactin responses between a test group with migraine and a matched group of healthy controls. Twelve female subjects fulfilling International Headache Society (IHS) criteria for migraine without aura were evaluated. Following an overnight fast, subjects presented for testing at 9am. An intravenous canula was inserted and serum prolactin was assessed at baseline and every 30 min for 3 h following a single dose of 30 mg oral buspirone, a 5-HT1A-receptor agonist. Subjects were assessed during the first 5 days of the menstrual cycle. No subjects were taking psychotropic medication or migraine prophylactic treatment. Patients with current or previous psychiatric disorder, daily headache or analgesic overuse were excluded. 16 healthy female volunteers matched for age and menstrual status were also evaluated and served as controls. There was no difference in baseline prolactin between groups. There was a significant rise in prolactin following buspirone in both groups. Subjects with migraine had a significantly increased prolactin response to buspirone (delta max) compared to controls (P < 0.001). This study supports the hypothesis that migraine without aura is associated with a relative hypersensitivity of central 5-HT1A receptors. This is of relevance given the role of the 5-HT1A receptor in controlling raphe 5-HT tone and in the possible association between migraine and anxiety and depression.