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Background and Purpose The Eph receptor tyrosine kinases and their ephrin ligands are key players in tumorigenesis and many reports have correlated changes in their expression with a poor clinical prognosis in many solid tumours. Agents targeting the Eph-ephrin system might emerge as new tools useful for the inhibition of different components of cancer progression. Even if different classes of small molecules targeting Eph-ephrin interactions have been reported, their use is hampered by poor chemical stability and low potency. Stable and potent ligands are crucial to achieve robust pharmacological performance. Experimental Approach Uni PR129 (the L-homo- Trp conjugate of lithocholic acid) was designed by means of computational methods, synthetized and tested for its ability to inhibit the interaction between the Eph A2 receptor and the ephrin- A1 ligand in an elisa binding study. The ability of Uni PR129 to disrupt Eph A2-ephrin- A1 interaction was functionally evaluated in a prostate adenocarcinoma cell line and its anti-angiogenic effect was tested in vitro using cultures of HUVECs. Key Results Uni PR129 disrupted Eph A2-ephrin- A1 interaction with Ki = 370 nM in an elisa binding assay and with low micromolar potency in cellular functional assays, including inhibition of Eph A2 activation, inhibition of PC3 cell rounding and disruption of in vitro angiogenesis, without cytotoxic effects. Conclusions and Implications The discovery of Uni PR129 represents not only a major advance in potency compared with the existing Eph-ephrin antagonists but also an improvement in terms of cytotoxicity, making this molecule a useful pharmacological tool and a promising lead compound. [ABSTRACT FROM AUTHOR]

Background and Purpose: The Eph receptor tyrosine kinases and their ephrin ligands are key players in tumorigenesis and many reports have correlated changes in their expression with a poor clinical prognosis in many solid tumours. Agents targeting the Eph-ephrin system might emerge as new tools useful for the inhibition of different components of cancer progression. Even if different classes of small molecules targeting Eph-ephrin interactions have been reported, their use is hampered by poor chemical stability and low potency. Stable and potent ligands are crucial to achieve robust pharmacological performance.Experimental Approach: UniPR129 (the L-homo-Trp conjugate of lithocholic acid) was designed by means of computational methods, synthetized and tested for its ability to inhibit the interaction between the EphA2 receptor and the ephrin-A1 ligand in an elisa binding study. The ability of UniPR129 to disrupt EphA2-ephrin-A1 interaction was functionally evaluated in a prostate adenocarcinoma cell line and its anti-angiogenic effect was tested in vitro using cultures of HUVECs.Key Results: UniPR129 disrupted EphA2-ephrin-A1 interaction with Ki = 370 nM in an elisa binding assay and with low micromolar potency in cellular functional assays, including inhibition of EphA2 activation, inhibition of PC3 cell rounding and disruption of in vitro angiogenesis, without cytotoxic effects.Conclusions and Implications: The discovery of UniPR129 represents not only a major advance in potency compared with the existing Eph-ephrin antagonists but also an improvement in terms of cytotoxicity, making this molecule a useful pharmacological tool and a promising lead compound. [ABSTRACT FROM AUTHOR]

Extensive morphological and neurochemical changes have been experimentally and clinically documented in the hypertrophied intestine located orally to a chronic partial stenosis of the lumen. Functional studies revealed not only disruption of the interdigestive motor complex in vivo and decreased efficiency of contraction but also preservation of the peristaltic reflex in vitro. Given the critical role played in intestinal peristalsis by the coordinated activity of the longitudinal (LM) and circular muscle (CM), this work focuses on the motor responses of LM and CM isolated from rat hypertrophied ileum following mechanical obstruction. Maximal contractions to both receptor (acetylcholine and substance P) and non-receptor (K+) mediated stimuli were up to 10-fold increased in hypertrophic CM rings compared with control tissues, while a higher potency of substance P was revealed in both hypertrophied muscle layers. Relaxations to vasoactive intestinal polypeptide and 8-Br-cGMP were more intense on prostaglandin F2α-contracted hypertrophic LM strips compared with control tissues and a general tendency towards increased relaxation was shared also by hypertrophic CM basal tone. The present results collectively suggest that hypertrophic growth leads to hyperresponsiveness to contractile agents, particularly evident in the CM, and to increased sensitivity to relaxing mediators, especially exhibited by the LM. In this regard, the complementary role exerted by each muscle layer and the plasticity of the intestinal tissue could both come into play to preserve the intestinal functions in a changing environment. [ABSTRACT FROM AUTHOR]

Chronic intestinal obstruction is associated with morphological changes and functional disorders clinically reported and experimentally documented in laboratory animals. In contrast, little is known about the properties of the hypertrophied intestine after removal of the obstruction. In the present study, we removed the ileal obstruction previously applied to the ileum of rats and, after 1 or 2 weeks, studied in vitro the motor responses of de-obstructed segments of intestine to pharmacological or electrical field stimulation (EFS). By 2 weeks after de-obstruction, maximal contractile responses to receptor (acetylcholine) and non-receptor (K+) mediated stimuli were comparable in operated and control tissues; furthermore, the loss of sensitivity to nitric oxide (NO) unmasked in obstructed tissues was, after de-obstruction, replaced by supersensitivity to exogenous NO and vasoactive intestinal polypeptide, probably acting through cyclic nucleotide-independent pathways. Despite the complete recovery of smooth muscle responses, neurogenic contractions remained impaired in de-obstructed tissue; however, the equal contribution of cholinergic/peptidergic components to EFS responses could represent a sign of gradual but delayed recovery of enteric neurotransmission. [ABSTRACT FROM AUTHOR]

The present work aims at investigating the changes in motor responsiveness of rat intestine hypertrophied by chronic mechanical obstruction. Motor responses to pharmacological agents and electrical field stimulation (EFS) were studied in hypertrophic ileal segments excised from rats subjected to experimental stenosis ( n = 20) and compared with responses of control tissues from sham-operated animals ( n = 20). Spontaneous motility and contractile responses to exogenous agents (KCl, acetylcholine and substance P) and EFS (10-s trains every minute, 120 mA, 0.5 ms, 1–10 Hz) were increased in hypertrophic longitudinal segments; however, normalization of motor responses to tissue wet weight revealed a remarkable reduction of contractile efficiency in hypertrophied tissues coupled with a loss of sensitivity to nitric oxide-mediated relaxation. Furthermore, EFS under non-adrenergic non-cholinergic (NANC) conditions unveiled a major role of the cholinergic component over the peptidergic one in the neurogenic contraction of hypertrophic intestine. On the whole, hypertrophic intestinal growth emerges as a dynamic process entailing adaptation of smooth muscle and neuronal structures to the increased functional load imposed by lumen obstruction. [ABSTRACT FROM AUTHOR]

Background Symptoms of digestive dysfunction in patients with Parkinson's disease ( PD) occur at all stages of the disease, often preceding the onset of central motor symptoms. On the basis of these PD-preceding symptoms it has been proposed that PD could initiate in the gut, and that the presence of alpha-synuclein aggregates, or Lewy bodies in the enteric nervous system might represent one of the earliest signs of the disease. Following this hypothesis, much research has been focused on the digestive tract to unravel the mechanisms underlying the onset and progression of PD, with particular attention to the role of alterations in enteric neurotransmission in the pathophysiology of intestinal motility disturbances. There is also evidence suggesting that the development of central nigrostriatal neurodegeneration is associated with the occurrence of gut inflammation, characterized by increments of tissue pro-inflammatory markers and oxidative stress, which might support conditions of bowel neuromotor abnormalities. Purpose The present review intends to provide an integrated and critical appraisal of the available knowledge on the alterations of enteric neuromuscular pathways regulating gut motor activity both in humans and preclinical models of PD. Moreover, we will discuss the possible involvement of neuro-immune mechanisms in the pathophysiology of aberrant gastrointestinal gut transit and neuromuscular activity in the small and large bowel. [ABSTRACT FROM AUTHOR]

1 Possible effects of new and conventional H3-receptor antagonists towards various non-histaminergic receptors (α2-adrenergic, 5-HT3-serotonin, μ-opiate, A1-adenosine, M1-and M3-muscarinic) involved in neurogenic and myogenic contractile responses of guinea-pig ileum are investigated. 2 When the isolated ileum was contracted by the 5-HT3 receptor agonist, 2-methyl-5-HT (5 × 10--7–8 × 10--6 m), acetylcholine (1 × 10--9–1 × 10--7 m), KCl (3 × 10--2 m) or electrical stimulation some of the drugs, included thioperamide and clobenpropit, reduced the contractile response when tested at micromolar concentrations (1–3 × 10--5 m) (only compound IV exhibited an M3 competitive antagonism with a pKB = 5.49 ± 0.18). 3 Ileal twitch responses to electrical stimulation were dose-dependently inhibited by the selective agonists clonidine (3 × 10--10–1 × 10--7 m), dermorphin (1 × 10--11–1 × 10--8 m), R-N6-(2-phenylisopropyl)-adenosine (1 × 10--9–3 × 10--8 m) and McN-A-343 (1 × 10--7–1 × 10--5 m) with different potencies and comparable efficacy (spike amplitude reduction > 85%). All the H3 antagonists under study (up to 1 × 10--5 m) showed no or minor interactions at the neuronal sites except the compound V which behaved as a weak competitive antagonist at α2-adrenoreceptors (pKB = 5.96 ± 0.06). 4 In conclusion, both new and conventional H3-blockers interacted at the enteric neuronal sites here studied with a 1000–30 000 fold lower antagonistic potency than that previously reported for the ileal H3 histamine receptors. Their spasmolytic activity precludes firm conclusions about the non-competitive interaction with 5-HT3 ileal receptor which requires further investigations. [ABSTRACT FROM AUTHOR]