BackgroundThe protease BACE1 (beta-site APP cleaving enzyme) is a major drug target in Alzheimer’s disease. However, BACE1 therapeutic inhibition may cause unwanted adverse effects due to its additional functions in the nervous system, such as in myelination and neuronal connectivity. Additionally, recent proteomic studies investigating BACE1 inhibition in cell lines and cultured murine neurons identified a wider range of neuronal membrane proteins as potential BACE1 substrates, including seizure protein 6 (SEZ6) and its homolog SEZ6L.Methods and resultsWe generated antibodies against SEZ6 and SEZ6L and validated these proteins as BACE1 substrates in vitro and in vivo. Levels of the soluble, BACE1-cleaved ectodomain of both proteins (sSEZ6, sSEZ6L) were strongly reduced upon BACE1 inhibition in primary neurons and also in vivo in brains of BACE1-deficient mice. BACE1 inhibition increased neuronal surface levels of SEZ6 and SEZ6L as shown by cell surface biotinylation, demonstrating that BACE1 controls surface expression of both proteins. Moreover, mass spectrometric analysis revealed that the BACE1 cleavage site in SEZ6 is located in close proximity to the membrane, similar to the corresponding cleavage site in SEZ6L. Finally, an improved method was developed for the proteomic analysis of murine cerebrospinal fluid (CSF) and was applied to CSF from BACE-deficient mice. Hereby, SEZ6 and SEZ6L were validated as BACE1 substrates in vivo by strongly reduced levels in the CSF of BACE1-deficient mice.ConclusionsThis study demonstrates that SEZ6 and SEZ6L are physiological BACE1 substrates in the murine brain and suggests that sSEZ6 and sSEZ6L levels in CSF are suitable markers to monitor BACE1 inhibition in mice.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-016-0134-z) contains supplementary material, which is available to authorized users.

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tion attenuated anorexia after lipopolysaccharide (LPS) administration, we tested the ability of resveratrol (2.5, 10, and 40 mg/kg) and NS-398 (2.5, 10, and 40 mg/kg), selective inhibitors of the two COX isoforms COX-1 and -2, respectively, to attenuate LPS (100 g/kg ip)-induced anorexia. NS-398 (10 and 40 mg/kg) administered with LPS at lights out attenuated LPS-induced anorexia, whereas resveratrol at all doses tested did not. Because prostaglandin (PG) E2 is considered the major metabolite synthesized by COX, we measured plasma and cerebrospinal fluid (CSF) PGE2 levels after LPS administration. LPS induced a time-dependent increase of PGE2 in CSF but not in plasma. NS-398 (5, 10, and 40 mg/kg) blocked the LPS-induced increase in CSF PGE2, whereas resveratrol (10 mg/kg) did not. These results support a role of COX-2 in mediating the anorectic response to peripheral LPS and point at PGE2 as a potential neuromodulator involved in this response.NS-398; resveratrol; prostaglandin E2; food intake; fever LIPOPOLYSACCHARIDE (LPS) and proinflammatory cytokines [e.g., interleukin (IL)-1␤, IL-6, and tumor necrosis factor-␣] induce anorexia and fever (32), two phenomena partly independent of each other. Brain areas involved in feeding and body temperature regulation are activated (5, 40) after peripheral administration of LPS and cytokines. This can be accomplished through neural and/or humoral communications with the central nervous system (CNS). Vagal afferents have been implicated in some of the behavioral effects induced by peripheral LPS or cytokines (3, 16). In our hands, however, subdiaphragmatic vagal deafferentation, alone or in combination with celiac-superior mesenteric ganglionectomy, did not attenuate the anorectic response to peripheral LPS, muramyl dipeptide, and IL-1␤ (33). An alternative route of communication between the periphery and the CNS involves cytokine and LPS receptors on the surface of the cerebral endothelial cells of the brain-blood barrier (1, 39) and subsequent mediators such as prostaglandins (PGs) (6). PGs are synthesized by cyclooxygenase (COX), an enzyme that exists in two different isoforms. COX-1 is constitutively expressed in many tissues, mainly outside the brain, and its levels are relatively insensitive to inflammatory stimulation. COX-1 is scarcely expressed in capillary endothelial and perivascular glial cells (13). COX-2, on the other hand, is constitutively expressed at low levels in neurons of the cortex, hippocampus, and amygdala, but not in the cells of the cerebral vasculature (34). COX-2 is strongly induced in brain vasculature, however, by LPS and IL-1␤ (12,22,34). LPS or cytokines (31) transiently enhance COX-2 mRNA and protein levels via activation of nuclear factor-B (2, 23).In our hands, nonselective pharmacological inhibition of COX by administration of indomethacin or paracetamol attenuated the pyretic and hypophagic effects of peripheral 27). Selective inhibition of COX-2 blocks LPS-induced fever (7). Use of selective inhibitors for COX-1 and -2 could not establ...

Impaired transmission through glutamatergic circuits has been postulated to play a role in the underlying pathophysiology of schizophrenia. Furthermore, inhibition of the N-methyl-D-aspartate (NMDA) subtype of ionotropic glutamate receptors (NMDAR) induces a syndrome that recapitulates many of the symptoms observed in patients with schizophrenia. Selective activation of metabotropic glutamate receptor subtype 5 (mGlu 5 ) may provide a novel therapeutic approach for treatment of symptoms associated with schizophrenia through facilitation of transmission through central glutamatergic circuits. Here, we describe the characterization of two novel N-aryl piperazine mGlu 5 positive allosteric modulators (PAMs): 2-(4-(2-(benzyloxy)acetyl)piperazin-1-yl)benzonitrile (VU0364289) and 1-(4-(2,4-difluorophenyl)piperazin-1-yl)-2-((4-fluorobenzyl)oxy)ethanone (DPFE). VU0364289 and DPFE induced robust leftward shifts in the glutamate concentration-response curves for Ca 21 mobilization and extracellular signal-regulated kinases 1 and 2 phosphorylation. Both PAMs displayed micromolar affinity for the common mGlu 5 allosteric binding site and high selectivity for mGlu 5 . VU0364289 and DPFE possessed suitable pharmacokinetic properties for dosing in vivo and produced robust dose-related effects in reversing amphetamine-induced hyperlocomotion, a preclinical model predictive of antipsychotic-like activity. In addition, DPFE enhanced acquisition of contextual fear conditioning in rats and reversed behavioral deficits in a mouse model of NMDAR hypofunction. In contrast, DPFE had no effect on reversing apomorphine-induced disruptions of prepulse inhibition of the acoustic startle reflex. These mGlu 5 PAMs also increased monoamine levels in the prefrontal cortex, enhanced performance in a hippocampal-mediated memory task, and elicited changes in electroencephalogram dynamics commensurate with procognitive effects. Collectively, these data support and extend the role for the development of novel mGlu 5 PAMs for the treatment of psychosis and cognitive deficits observed in individuals with schizophrenia.

Many new substances are currently being investigated for their usefulness in the pharmaco-therapy of obesity. Most drugs interfere with monoamine neuro-transmitter (serotonin, noradrenalin, dopamine and histamine) effects and act as an appetite suppressant. Other approaches are to primarily increase thermogenesis (e.g. beta 3-adrenoceptor agonists), or to decrease fat absorption by inhibiting the pancreatic lipase (orlistat). New promising agents are substances that increase the effect of corticotropin releasing factor (CRF) or urocortin in the brain (CRF-binding protein ligand inhibitor) and a neuropeptide Y (NPY) Y5 receptor antagonist. The clinical relevance of leptin in the therapy of obesity is probably limited, but can not be fully evaluated at the moment. As obesity has a multifactorial basis, all these substances have in common the fact that they can not cure obesity. They should only be used as an adjunct to classical strategies like diet and exercise in severe obesity. For developing new, perhaps even more specific pharmacological agents, further research is needed to understand the individually different genetic and physiological basis of obesity.

Adenosine A2A antagonists are believed to have therapeutic potential in the treatment of Parkinson's disease (PD). We have characterized the dual adenosine A2A/A1 receptor antagonist JNJ-40255293 (2-amino-8-[2-(4-morpholinyl)ethoxy]-4-phenyl-5H-indeno[1,2-d]pyrimidin-5-one). JNJ-40255293 was a high-affinity (7.5 nM) antagonist at the human A2A receptor with 7-fold in vitro selectivity versus the human A1 receptor. A similar A2A:A1 selectivity was seen in vivo (ED50's of 0.21 and 2.1 mg/kg p.o. for occupancy of rat brain A2A and A1 receptors, respectively). The plasma EC50 for occupancy of rat brain A2A receptors was 13 ng/mL. In sleep-wake encephalographic (EEG) studies, JNJ-40255293 dose-dependently enhanced a consolidated waking associated with a subsequent delayed compensatory sleep (minimum effective dose: 0.63 mg/kg p.o.). As measured by microdialysis, JNJ-40255293 did not affect dopamine and noradrenaline release in the prefrontal cortex and the striatum. However, it was able to reverse effects (catalepsy, hypolocomotion, and conditioned avoidance impairment in rats; hypolocomotion in mice) produced by the dopamine D2 antagonist haloperidol. The compound also potentiated the agitation induced by the dopamine agonist apomorphine. JNJ-40255293 also reversed hypolocomotion produced by the dopamine-depleting agent reserpine and potentiated the effects of l-dihydroxyphenylalanine (L-DOPA) in rats with unilateral 6-hydroxydopamine-induced lesions of the nigro-striatal pathway, an animal model of Parkinson's disease. Extrapolating from the rat receptor occupancy dose-response curve, the occupancy required to produce these various effects in rats was generally in the range of 60-90%. The findings support the continued research and development of A2A antagonists as potential treatments for PD.

We investigated the extrinsic gut neural mediation of the suppression of food intake in male Sprague-Dawley rats induced by peripheral intraperitoneal administration of 2 μg/kg interleukin-1β (IL-1β), 100 μg/kg bacterial lipopolysaccharide (LPS), and 2 mg/kg muramyl dipeptide (MDP). Food intake during the first 3 and 6 h of the dark cycle was measured in rats with subdiaphragmatic vagal deafferentation ( n = 9), celiac superior mesenteric ganglionectomy ( n = 9), combined vagotomy and ganglionectomy ( n = 9), and sham deafferentation ( n = 9). IL-1β, LPS, and MDP suppressed food intake at 3 and 6 h in all surgical groups. The results demonstrate that neither vagal nor nonvagal afferent nerves from the upper gut are necessary for the feeding-suppressive effects of intraperitoneal IL-1β, LPS, or MDP in the rat and suggest that peripheral administration of immunomodulators produces anorexia via a humoral pathway.

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