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Peptides participating in the hypothalamic control of feeding behaviour are also involved in the central autonomic control of gastrointestinal functions, such as secretion and motility. An anatomical interaction and functional relationship in the central nervous system between the feeding-related peptides neuropeptide Y and ghrelin is well documented. Furthermore, it has been shown that feeding-related peptides can influence digestive function via central corticotrophin-releasing factor (CRF) pathways. In the present study, we investigated the role of ghrelin in the central autonomic control of colonic motility. Furthermore, we addressed the hypothesis that ghrelin is involved in the hypothalamic control of colonic motor function, utilizing central neuropeptide Y receptors and hypothalamic CRF pathways. Ghrelin (0.03, 0.06 and 0.12 nmol) bilaterally microinjected into the paraventricular nucleus (PVN) induced a significant stimulation of colonic propulsion. In particular, the colonic transit time decreased from 312 ± 7 min to 198 ± 12 min. Microinjection of the neuropeptide Y1 receptor antagonist, BIBP-3226 (200 pmol), or the nonselective CRF receptor antagonist, astressin (30 pmol), into the PVN abolished the stimulatory effect of ghrelin injected into the PVN on colonic transit time, whereas pretreatment with the selective CRF2 receptor, antisauvagine-30 (28 pmol), failed to affect the effect of PVN-ghrelin injection on colonic propulsion. These results suggest that ghrelin can act as central modulator of gastrointestinal motor functions at the level of the PVN via neuropeptide Y1- and CRF1 receptor-dependent mechanisms. [ABSTRACT FROM AUTHOR]

Purpose: To characterize the pattern of contrast-enhanced ultrasonography (CEUS) in splenic metastases compared to standard B-mode ultrasonography., Materials and Methods: Between January 2004 and March 2009, about 50,000 abdominal ultrasound examinations were performed, and n = 279 (< 0.6 %) of focal splenic lesions were detected of which n = 32 (11.5 %) were highly suggestive for splenic metastases of various solid tumors. The number of lesions, size, echogenicity, rim appearance, presence of halo sign and necrosis were recorded via B-mode sonography. Contrast enhancement was determined in the arterial phase (5 - 30 sec) and parenchymal phase (3 - 5 min). B-mode sonography and CEUS were compared in terms of the visibility of splenic metastases. All data was evaluated retrospectively., Results: On B-mode sonography lesions were solitary n = 18 (56 %), multiple n = 14 (44 %), < 2 cm n = 11 (34 %), > or = 2 cm n = 21 (66 %), hypoechoic n = 14 (44 %), isoechoic n = 12 (38 %) and hyperechoic n = 6 (19 %), with regular rim appearance n = 27 (84 %), and with irregular rim appearance n = 5 (16 %). During the arterial phase CEUS lesions were hypoechoic n = 21 (66 %), isoechoic n = 2 (6 %), hyperechoic n = 1 (3 %) and complex n = 8 (25 %). During the parenchymal phase lesions were hypoechoic n = 24 (75 %) and complex n = 8 (25 %). CEUS provided improved visualization of splenic metastases in n = 12 (38 %) cases., Conclusion: CEUS of splenic metastases is characterized by reduced contrast enhancement in both the arterial and the parenchymal phase in most cases. Moreover, CEUS improved the visualization of splenic metastases in about 40 % of cases in comparison to standard B-mode sonography., (Copyright Georg Thieme Verlag KG Stuttgart . New York.)

Psychological stress is widely believed to play a major role in functional gastrointestinal (GI) disorders, especially irritable bowel syndrome (IBS), by precipitating exacerbation of symptoms. The available data clearly demonstrate that inhibition of gastric emptying and stimulation of colonic transit is the most consistent pattern in the motility response of the GI tract to acute or short-term stress. Thus, one might propose that these alterations might play a pathophysiological role in dyspeptic symptoms and alterations in stool frequency and consistency in patients with stress-related functional GI disorders. Taken together, the above-mentioned studies suggest that the colonic motor response to stress is exaggerated in IBS. There is evidence that an increased emotional response is associated with this difference in colonic, and perhaps also gastric motor responses to certain stressors. However, almost no valid data are available so far from human studies addressing the question if differences in motility responses to stress between patients with functional GI disorders and healthy subjects are due to an altered stress response associated with an imbalance of the autonomic nervous system or increased stress susceptibility. We can summarize that in experimental animals the most consistent pattern of GI motor alterations induced by various psychological and physical stressors is that of delaying gastric emptying and accelerating colonic transit. Endogenous corticotropin-releasing factor (CRF) in the brain plays a significant role in the central nervous system mediation of stress-induced inhibition of upper GI and stimulation of lower GI motor function through activation of brain CRF receptors. The inhibition of gastric emptying by CRF may be mediated by interaction with the CRF-2 receptor, while CRF-1 receptors are involved in the colonic and anxiogenic responses to stress. Endogenous serotonin, peripherally released in response to stress, seems to be involved in stress- and central CRF-induced stimulation of colonic motility by acting on 5HT-3 receptors. Taken together, the limited data available from investigations in healthy subjects and patients with functional GI disorders provide some evidence that stress affects visceral sensitivity in humans. Acute psychological stress seems to facilitate increased sensitivity to experimental visceral stimuli, if the stressor induces a significant emotional change. In summary, studies in experimental animals suggest that stress-induced visceral hypersensitivity is centrally mediated by endogenous CRF and involvement of structures of the emotional motor system, e.g. the amygdala. Stress-induced activation or sensitization of mucosal mast cells in the GI tract seem to be involved in stress-associated alterations of visceral sensitivity., (Copyright 2001 S. Karger AG, Basel)