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Angiotensin II (Ang II) is a newly discovered modulator of intestinal motility, mainly via activation of excitatory AT1 receptors (AT1R). We demonstrated that during gut inflammation there is a recruitment of inhibitory AT2 receptors (AT2R) which would counteract the AT1R-induced effects. Our objective was to explore the consequence of AT2R activation in the pathogenesis of experimental colitis. Colitis was induced in rats by intrarectal administration of 2,4-Dinitrobenzene sulfonic acid (DNBS). Colonic damage was assessed by macro- and microscopic scores, myeloperoxidase activity and inflammatory cytokine expression on day 6 after colitis induction. Colonic contractility was recorded in vitro. In a separate group of animals, the effects of 6-day intraperitoneal treatment with PD123319 (3 mg/kg) on colitis features were examined. Colon from DNBS-rats showed marked inflammation associated to a decrease of spontaneous and evoked mechanical activity. Ang II contractile response was reduced by the activation of inhibitory AT2 receptors. PD123319, AT2R antagonist, per se ameliorated colonic contractility. Inhibition of nitric oxide synthase or neural activity induced as well an increase of contractility in DNBS preparations. In such conditions PD123319 did not induce further effects. In DNBS rats daily i.p. treatment with PD123319, attenuated colitis severity, reducing body weight loss and incidence of diarrhoea and improving mechanical activity in vitro. In conclusion, during inflammation constitutively activated AT2 receptors via involvement of enteric nerves and NO would contribute to the reduction of muscle contractility. Blocking AT2R activation in vivo seems to improve some symptoms during intestinal inflammation, driving future study.

A growing body of evidence shows that Insulin, Insulin Receptor (IR) and IR signaling are involved in brain cognitive functions and their dysfunction is implicated in neuronal degeneration associated with Alzheimer's disease (AD). Thus, the administration of insulin to the brain could be a strategy for the prevention and treatment of AD disease. With this aim, we have designed, synthesized and characterized a nanogel system (NG) that can be used as substrate for the conjugation of insulin and/or fluorescent molecules relevant for their characterization. In particular, a carboxyl-functionalized poly(N-vinyl pyrrolidone) nanogel system, has been produced by ionizing radiation starting from the polymeric aqueous solution and four insulin molecules per nanogel have been irreversibly attached. Absence of cytotoxicity, oxidative stress and mitochondrial dysfunction support the biocompatibility of the “naked” nanogels. Their hemocompatibility has been demonstrated by hemolysis, coagulation time, leukocyte proliferation and inflammatory response tests. By fluorescence measurements we have demonstrated that the insulin conjugated to the NG (NG-In) is protected by protease degradation and is able to bind and activate insulin receptor, thus triggering insulin signaling via AKT activation. In order to provide more significant evidence of the functionality of the insulin conjugated to the nanoparticles at the body level, the effect of NG-In in reducing the plasma glucose levels in mice has been demonstrated. Neuroprotection of NG-In against dysfunction induced by amyloid β, a peptide mainly involved in AD, has been also verified. Finally, the potential of NG-In to be efficiently transported across the Blood Brain Barrier has been demonstrated in vitro. All together, these results indicate that the synthesized NG-In is a suitable vehicle system for insulin deliver and a very promising tool to develop new therapies for neurodegenerative diseases

Background Glucagon-like peptide-1 (GLP-1) is a proglucagon-derived peptide expressed in the enteroendocrine-L cells of small and large intestine and released in response to meal ingestion. Glucagon-like peptide-1 exerts inhibitory effects on gastrointestinal motility through vagal afferents and central nervous mechanisms; however, no data is available about a direct influence on the gastrointestinal wall. Our aim was to investigate the effects of GLP-1 on the spontaneous and evoked mechanical activity of mouse duodenum and colon and to identify the presence and distribution of GLP-1 receptors (GLP-1R) in the muscle coat. Methods Organ bath recording technique and immunohistochemistry were used. Key Results Glucagon-like peptide-1 (up to the concentration of 1 lmol L)1) failed to affect spontaneous mechanical activity. It caused concentration-dependent reduction of the electrically evoked cholinergic contractions in circular smooth muscle of both intestinal segments, without affecting the longitudinal muscle responses. Glucagon-like peptide-1 inhibitory effect was significantly antagonized by exendin (9–39), an antagonist of GLP-1R. In both intestinal preparations, GLP-1 effect was not affected by guanethidine, a blocker of adrenergic neurotransmission, but it was significantly reduced by Nx-nitro-L-arginine methyl ester, inhibitor of nitric oxide (NO) synthase. Glucagon- like peptide-1 failed to affect the contractions evoked by exogenous carbachol. Immunohistochemistry demonstrated GLP-1R expression in the enteric neurons. Furthermore, 27% of GLP-1R immunoreactive (IR) neurons in the duodenum and 79% of GLP- 1R-IR neurons in the colon, co-expressed nNOS. Conclusions & Inferences The present results suggest that GLP-1 is able to act in the enteric nervous system by decreasing the excitatory cholinergic neurotransmission through presynaptic GLP-1Rs, which modulate NO release.

1. The aim of the present study was to examine the role of NK1 and NK2 receptors in the control of mechanical activity of mouse stomach. In this view, the motor effects induced by NK1 and NK2 receptor agonists and antagonists were analyzed, measuring motility as intraluminal pressure changes in mouse-isolated stomach preparations. In parallel, immunohistochemical studies were performed to identify the location of NK1 and NK2 receptors on myenteric neurons and smooth muscle cells. 2. Substance P (SP) induced biphasic effects: a contraction followed by relaxation; neurokinin A (NKA) and [beta-Ala8]-NKA(4-10), selective agonist of NK2 receptors, evoked concentration-dependent contractions, whereas [Sar9, Met(O2)11]-SP, selective agonist of NK1 receptors, induced concentration-dependent relaxation. 3. SR48968, NK2 receptor antagonist, did not modify the spontaneous activity and reduced the contractile effects induced by tachykinins without affecting the relaxation. SR140333, NK1 receptor antagonist, did not modify the spontaneous activity and antagonized the relaxant response to tachykinins, failing to affect the contractile effects. 4. The relaxation to SP or to [Sar9, Met(O2)11]-SP was abolished by tetrodotoxin (TTX) and significantly reduced by N(omega)-nitro-L-arginine methyl ester (L-NAME). 5. NK2-immunoreactivity (NK2-IR) was seen at the level of the smooth muscle cells of both circular and longitudinal muscle layers. NK1-immunoreactive (NK1-IR) neurons were seen in the myenteric ganglia and NK1/nNOS double labeling revealed that some neurons were both NK1-IR and nNOS-IR. 6. These results suggest that, in mouse stomach, NK1 receptors, causing relaxant responses, are present on nitrergic inhibitory myenteric neurons, whereas NK2 receptors, mediating contractile responses, are present at muscular level.

Neurodegeneration consists in loss of neuron specific types, pattern and distribution, leading to progressive dysfunctions of the central nervous system. Neurodegenerative diseases include diverse pathological conditions, among which Alzheimer’s and Parkinson’s diseases are the most prevalent ones. Alzheimer’s disease is known as a growing dementia, characterized by progressive language, memory, and cognitive loss, while Parkinson’s disease is primarily characterized as a motor disorder. Senile plaques, caused by amyloid β peptide, hyperphosphorylated tau-based neurofibrillary tangles and synapse loss, are the principal pathological hallmarks of Alzheimer’s disease. Amyloid β oligomer formation is associated with development of reactive oxygen and nitrogen species, inflammation, calcium-dependent excitotoxicity, impairment of cellular respiration, and alteration of synaptic functions related with learning and memory. Parkinson’s disease is produced by dopaminergic neuron deterioration in the extrapyramidal tract of the midbrain. Accumulation of α-synuclein proteins (Lewy bodies) in the central, autonomic, and peripheral nervous system is the hallmark of the Parkinson’s disease. The Levy bodies break the neuronal membrane leading to neuronal death through oxidative stress, excitotoxicity, energy failure and neuroinflammation.

Obesity constitutes a major global health threat and is associated with a variety of diseases ranging from metabolic and cardiovascular disease, cancer to neurodegeneration. The hallmarks of neurodegeneration include oxidative stress, proteasome impairment, mitochondrial dysfunction and accumulation of abnormal protein aggregates as well as metabolic alterations. As an example, in post-mortem brain of patients with Alzheimer’s disease (AD), several studies have reported reduction of insulin, insulin-like growth factor 1 and insulin receptor and an increase in tau protein and glycogen-synthase kinase-3β compared to healthy controls suggesting an impairment of metabolism in the AD patient’s brain. Given these lines of evidence, in the present study we investigated brains of mice treated with 2 obesogenic diets, high-fat diet (HFD) and high-glycaemic diet (HGD), compared to mice fed with a standard diet (SD) employing a quantitative mass spectrometry-based approach. Moreover, post-translational modified proteins (phosphorylated and N-linked glycosylated) were studied. The aim of the study was to identify proteins present in the brain that are changing their expression based on the diet given to the mice. We believed that some of these changes would highlight pathways and molecular mechanisms that could link obesity to brain impairment. The results showed in this study suggest that, together with cytoskeletal proteins, mitochondria and metabolic proteins are changing their post-translational status in brains of obese mice. Specifically, proteins involved in metabolic pathways and in mitochondrial functions are mainly downregulated in mice fed with obesogenic diets compared to SD. These changes suggest a reduced metabolism and a lower activity of mitochondria in obese mice. Some of these proteins, such as PGM1 and MCT1 have been shown to be involved in brain impairment as well. These results might shed light on the well-studied correlation between obesity and brain damage. The results presented here are in agreement with previous findings and aim to open new perspectives on the connection between diet-induced obesity and brain impairment.

Growing evidence suggests a link between obesity and neurodegeneration. The purpose of the present study was to explore the neuroprotective potential of glucagon-like peptide-2 (GLP-2) in the brain of high fat diet (HFD)-fed mice. Markers of inflammation and oxidative stress were analysed in the brains of obese mice chronically treated with [Gly2]-GLP-2 (teduglutide), the stable analogue of the GLP-2, and they were compared to age-matched untreated obese and lean animals. Neurodegeneration was examined by TUNEL assay. HFD feeding increased the expression of pro-inflammatory mediators (NF-kB, IL-8, TNF-α, IL-1β and IL-6), glial fibrillary acidic protein (GFAP), index of gliosis and neurodegeneration, stress marker proteins (p-ERK, Hsp60 and i-NOS), amyloid-β precursor protein (APP). [Gly2]-GLP-2 treatment significantly attenuated the HFD-induced increased expression of the various markers, as well as the higher levels of reactive oxygen species found in brains of untreated-HFD mice. Immunofluorescence confirmed that the increase of GFAP or APP in the brain cortex of HFD mice were less prominent in the [Gly2]-GLP-2 treated group. TUNEL-positive cell number in brain sections of [Gly2]-GLP-2-treated HFD-fed mice was significantly lesser in comparison with untreated-HFD animals and similar to STD fed mice. In conclusion, the results of the present study suggest that GLP-2 stable analogue improves the obesity-associated neuroinflammation and the central stress conditions, it reduces the neuronal apoptotic death, providing evidence for a neuroprotective role of the peptide.