Experience with anxiety and depression treatment studies: implications for designing irritable bowel syndrome clinical trials

Colorectal distention induces hippocampal noradrenaline release in rats: an in vivo microdialysis study

We tested our hypothesis that noradrenaline is released in the hippocampus by colorectal distention of rats, and that it induces pain-related behavior. Noradrenaline levels with colorectal distention were significantly higher than those with restraint stress and free moving. Abdominal contractions were induced only by colorectal distention. Our results suggest that noradrenaline levels increase in the hippocampus under colorectal distention and this may relate to behavioral changes.

Evolving pathophysiologic models of functional gastrointestinal disorders

In contrast to most other disorders of the digestive system, functional disorders of the gut continue to be defined by symptom criteria rather than by biological markers. At the same time, animal models of functional gastrointestinal disorders in which to test pathophysiologic hypotheses are lacking. The aim of this report is to critically review recently proposed conceptual as well as animal models of functional gastrointestinal disorders. Converging disease models have been proposed that postulate an enhanced responsiveness of neural, immune, or neuroimmune circuits in the central nervous system or in the gut to exteroceptive (psychosocial) or interoceptive (tissue irritation, inflammation, infection) perturbations of the organism's homeostasis. The enhanced responsiveness results in dysregulation of gut motility, epithelial function (immune, permeability), and visceral hypersensitivity, which in turn produce irritable bowel syndrome symptoms. These conceptual models provide plausible mechanisms for irritable bowel syndrome symptom generation and are consistent with extensive epidemiologic and pathophysiologic data. Several animal models have recently been proposed that mimic key features of these conceptual disease models. They fall into models triggered by centrally targeted stimuli (neonatal stress, post-traumatic stress disorder) or those triggered by peripherally targeted stimuli (infection, inflammation). Depending on the timing of the trigger (neonatal vs. adult), the changes induced in the animal may be permanent or transient. Future development of existing and novel models involves the use of transgenic and knockout animals, as well as the demonstration of predictive validity in terms of responsiveness to candidate drugs.

Paroxetine in Patients With Irritable Bowel Syndrome: A Pilot Open-Label Study

BACKGROUND: Irritable bowel syndrome (IBS) is a common disorder and is the largest diagnostic cohort seen by gastroenterologists. There is a bidirectional comorbidity of IBS and psychiatric illness. Ours is the first study to examine the effect of any selective serotonin reuptake inhibitor in subjects with IBS. METHOD: Twenty subjects with Rome I criteria-diagnosed IBS were treated with 20 to 40 mg of paroxetine for 12 weeks. We utilized a computer-administered patient daily questionnaire taken by patients over the telephone using an interactive voice response system. RESULTS: Sixty-five percent of patients (13/20) reported a reduction in abdominal pain, and 55% (11/20) reported a reduction in pain frequency (total or mean number of days per week in which the patient had the symptom decreased by >/= 50%). Constipation and diarrhea were reduced in 69% and 57% of patients (9/13 and 8/14), respectively. Similarly, a clinically significant reduction in the symptoms of feeling of incomplete emptying (53% [9/17]) and bloating/abdominal distension (55% [11/20]) was apparent at study conclusion compared with baseline. On the Clinical Global Impressions scale at week 12, 47% (8/17) of the patients were much or very much improved. CONCLUSION: In our pilot open-label study, paroxetine was very effective in alleviating the abdominal pain and associated symptoms of IBS. These results warrant further examination in a placebo-controlled study.

Neuroendocrinology of stress

Stimuli that are interpreted by the brain as extreme or threatening, regardless of their modality, elicit an immediate stereotypic response characterized by enhanced cognition, affective immobility, vigilance, autonomic arousal and a global catabolic state. The brain's ability to mobilize this so-called stress response is paralleled by activation of corticotropin-releasing hormone (CRH) in several nuclei, including the hypothalamus, amygdala and locus ceruleus, and stimulation of the locus ceruleus norepinephrine (LC/NE) system in the brain stem. These systems perpetuate one another, interact with several other transmitter systems in the brain and directly activate the hypothalamic-pituitary-adrenal (HPA) axis and the three components of the autonomic nervous system, namely the sympatho-adrenal, the cranio-sacral parasympathetic and the enteric nervous systems. The widespread body system responses to stress are discussed, and the implications of aberrant stress system activity on physical and mental health are outlined. Moreover, the promise of nonpeptide CRH type-1 receptor antagonists to directly target the stress system in the brain is highlighted.

Adult outcomes of pediatric recurrent abdominal pain: do they just grow out of it?

OBJECTIVE

To determine whether medically unexplained recurrent abdominal pain (RAP) in childhood predicts abdominal pain, irritable bowel syndrome (IBS), other somatic complaints, and psychiatric symptoms and disorders in young adulthood.

METHODS

A sample of 28 young adults evaluated for RAP between the ages of 6 and 17 years were compared with 28 individually matched former childhood participants in a study of tonsillectomy and adenoidectomy. RAP caseness was established by structured retrospective chart review requiring agreement by 2 independent reviewers. Standardized assessments of abdominal pain, IBS, other somatic symptoms, psychopathology, perceived health, and history of maltreatment were performed an average of 11.1 years after the index visit.

RESULTS

Former RAP patients were significantly more likely than controls to endorse anxiety symptoms and disorders, hypochondriacal beliefs, greater perceived susceptibility to physical impairment, poorer social functioning, current treatment with psychoactive medication, and generalized anxiety in first degree relatives. There were trends suggesting associations between childhood RAP and lifetime psychiatric disorder, depression, migraine, and family history of depression, but group differences on abdominal pain, IBS, other somatic symptoms, and history of maltreatment were not statistically significant.

CONCLUSIONS

There is a strong and relatively specific association between childhood RAP and anxiety in young adulthood. Affected children may be at special risk to perceive physical symptoms as threatening, and should be evaluated for psychiatric disorder on initial presentation.

Characteristics of patients with irritable bowel syndrome recruited from three sources: implications for clinical trials

BACKGROUND

Variation in the characteristics of irritable bowel syndrome patients recruited for clinical trials from different sources could affect their response and the generalizability of trial results.

AIM

To describe and compare the characteristics of three different groups of irritable bowel syndrome patients recruited into a 'mock clinical trial.'

METHODS

We enrolled 245 irritable bowel syndrome patients from three sources: (i) 121 from British primary practitioners; (ii) 72 from California newspaper advertisements; and (iii) 52 from a California gastroenterologist's practice. We obtained demographic, clinical, and Hospital Anxiety and Depression (HAD) Scale data.

RESULTS

Most patients were young to middle-aged women; the majority reported symptoms for > 5 years in all three groups. Subject characteristics varied among the groups. Typically, primary care patients were anxious, smokers and daily alcohol drinkers who had sought care recently for irritable bowel syndrome and tried antispasmodic drugs. Their symptoms were intermediate in severity between those of the other two groups. Advertisement subjects were the oldest, most highly educated, most often depressed, and were least likely to have sought care recently for symptoms, which were almost uniformly only moderate in severity. Gastroenterologist patients tended to be anxious and had nearly all sought care recently for symptoms, which were the most severe and most likely to include all three pain-related Rome I criteria.

CONCLUSION

Recruitment methodology affects important characteristics of an irritable bowel syndrome study group.

Role of CRF receptor 1 in central CRF-induced stimulation of colonic propulsion in rats

The CRF receptor subtype mediating the colonic and gastric motor responses to central CRF was investigated in conscious rats. CRF (0.6 microg/rat) injected intracerebroventicularly (i.c.v.) or 1 h water avoidance stress stimulated defecation (pellet/60 min: 4.1+/-1.0 and 8.7+/-0.7 respectively vs. 0.3+/-0.3 in i.c.v. vehicle/no stress). The CRF receptor 1 (CRF-R1) antagonist, NBI-27914 (50-100 microg/rat) injected i.c.v., abolished the colonic response to i.c.v. CRF and dose-dependently reduced that induced by water avoidance stress. NBI-27914 (100 microg/rat) injected peripherally did not influence the defecatory response to stress. The peptide CRF-R1/R2 antagonist, astressin (10 microg/rat, i.c.v.) inhibited the colonic motor response to i.c.v. CRF and stress similarly as NBI-27914 injected i.c.v. at 100 microg/rat. Intracisternal (i.c.) injection of astressin (10 microg/rat) also completely prevented CRF (0.6 g, i.c.)-induced delayed gastric emptying while i.c. NBI-27914 (50 or 100 microg) had no effect. These results indicate a differential role of central CRF receptor subtypes in the colonic stimulatory and gastric inhibitory motor responses to central CRF and that the CRF component of stress-related activation of colonic expulsion is primarily mediated by CRF-R1.