As populations increase their life expectancy, age-related neurodegenerative disorders such as Alzheimer's disease have become more common. I 2 -Imidazoline receptors (I 2 -IR) are widely distributed in the central nervous system, and dysregulation of I 2 -IR in patients with neurodegenerative diseases has been reported, suggesting their implication in cognitive impairment. This evidence indicates that high-affinity selective I 2 -IR ligands potentially contribute to the delay of neurodegeneration. In vivo studies in the female senescence accelerated mouse-prone 8 mice have shown that treatment with I 2 -IR ligands, MCR5 and MCR9, produce beneficial effects in behavior and cognition. Changes in molecular pathways implicated in oxidative stress, inflammation, synaptic plasticity, and apoptotic cell death were also studied. Furthermore, treatments with these I 2 -IR ligands diminished the amyloid precursor protein processing pathway and increased Aβ degrading enzymes in the hippocampus of SAMP8 mice. These results collectively demonstrate the neuroprotective role of these new I 2 -IR ligands in a mouse model of brain aging through specific pathways and suggest their potential as therapeutic agents in brain disorders and age-related neurodegenerative diseases.

The imidazoline I receptors (I-IRs) are widely distributed in the brain, and I-IR ligands may have therapeutic potential as neuroprotective agents. Since structural data for I-IR remains unknown, the discovery of selective I-IR ligands devoid of α-adrenoceptor (α-AR) affinity is likely to provide valuable tools in defining the pharmacological characterization of these receptors. We report the pharmacological characterization of a new family of (2-imidazolin-4-yl)phosphonates. Radioligand binding studies showed that they displayed a higher affinity for I-IRs than idazoxan, and high I/α selectivity. In vivo studies in mice showed that acute treatments with 1b and 2c significantly increased p-FADD/FADD ratio (an index of cell survival) in the hippocampus when compared with vehicle-treated controls. Additionally, acute and repeated treatments with 2c, but not with 1b, markedly reduced hippocampal p35 cleavage into neurotoxic p25. The present results indicate a neuroprotective potential of (2-imidazolin-4-yl)phosphonates acting at I-IRs.

Imidazoline I 2 receptors (I 2-IR), widely distributed in the CNS and altered in patients that suffered from neurodegenerative disorders, are orphan from the structural point of view and new I 2-IR ligands are urgently required for improving their pharmacological characterization. We report the synthesis and 3D-QSAR studies of a new family of bicyclic -iminophosphonates endowed with relevant affinities for human brain I 2-IR. Acute treatment in mice with a selected compound significantly decreased the FADD protein in the hippocampus, a key marker in neuroprotective actions. Additionally, in vivo studies in the familial Alzheimer's disease 5xFAD murine model revealed beneficial effects in behavior and cognition. These results are supported by changes in molecular pathways related to cognitive decline and Alzheimer's disease. Therefore bicyclic -iminophosphonates are tools that may open new therapeutic avenues for I 2-IR, particularly for unmet neurodegenerative conditions.

Changes in phosphoenolpyruvate (PEP) concentrations secondary to variations in glucose availability can regulate calcium signaling in T cells as this metabolite potently inhibits the sarcoplasmic reticulum Ca 2+ /ATPase pump (SERCA). This regulation is critical to assert immune activation in the tumor as T cells and cancer cells compete for available nutrients. We examined here whether cytosolic calcium and the activation of downstream effector pathways important for tumor biology are influenced by the presence of glucose and/or cataplerosis through the phosphoenolpyruvate carboxykinase (PEPCK) pathway, as both are hypothesized to feed the PEP pool. Our data demonstrate that cellular PEP parallels extracellular glucose in two human colon carcinoma cell lines, HCT-116 and SW480. PEP correlated with cytosolic calcium and NFAT activity, together with transcriptional up-regulation of canonical targets PTGS2 and IL6 that was fully prevented by CsA pre-treatment. Similarly, loading the metabolite directly into the cell increased cytosolic calcium and NFAT activity. PEP-stirred cytosolic calcium was also responsible for the calmodulin (CaM) dependent phosphorylation of c-Myc at Ser62, resulting in increased activity, probably through enhanced stabilization of the protein. Protein expression of several c-Myc targets also correlated with PEP levels. Finally, the participation of PEPCK in this axis was interrogated as it should directly contribute to PEP through cataplerosis from TCA cycle intermediates, especially in glucose starvation conditions. Inhibition of PEPCK activity showed the expected regulation of PEP and calcium levels and consequential downstream modulation of NFAT and c-Myc activities. Collectively, these results suggest that glucose and PEPCK can regulate NFAT and c-Myc activities through their influence on the PEP/Ca 2+ axis, advancing a role for PEP as a second messenger communicating metabolism, calcium cell signaling, and tumor biology.

Background and Purpose: The development of effective therapeutic strategies against Alzheimer's disease (AD) remains a challenge. I 2 imidazoline receptor ligands have a neuroprotective role in AD. Moreover, co-treatment of AChE inhibitors with neuroprotective agents have shown better effects on the prevention of dementia.Here, we assessed the potential therapeutic effect of the I 2 ligand, donepezil and their combination in 5XFAD mice. Experimental Approach: 5XFAD female mice were treated with low doses (1 mgÁkg À1 Áday À1 ) of LSL60101, donepezil and donepezil plus LSL60101, during 4 weeks per os. Novel object recognition, Morris water maze, open field, elevated plus maze and three-chamber tests were used to evaluate the cognitive and behavioural status after treatment. The effects on AD-like pathology were assessed with immunohistochemistry, western blot, ELISA and qPCR. Key Results: Chronic low-dose treatment with LSL60101 and donepezil reversed cognitive deficits and impaired social behaviour. LSL60101 treatment did not affect anxiety-like behaviour in contrast to donepezil. In the 5XFAD brains, LSL60101 and donepezil/LSL60101 treatments attenuated amyloid-β pathology by decreasing amyloid-β 40 and amyloid-β 42 levels, amyloid-β plaque number and tau hyperphosphorylation. These alterations were accompanied by reduced microglia marker Iba-1 levels and increased Trem2 gene expression. LSL60101 and donepezil decreased glial fibrillary acidic protein (GFAP) astrocytic marker reactivity. However, only LSL60101 and donepezil/LSL60101 treatments significantly increased the synaptic marker levels of post-synaptic density protein 95 and synaptophysin. Conclusion and Implications:Chronic low-dose treatment with selective I 2 -ligands can be an effective treatment for AD and provide insights into combination treatments for symptomatic and disease-modifying drugs.