Endothelin-1 response to mental stress in early ischemic lesions of the extremities due to systemic sclerosis

We studied circulating levels of endothelin-1, catecholamines and nitric oxide after a mental arithmetic test in 14 patients with early ischemic lesions of the extremities due to systemic sclerosis and slightly impaired peripheral vascular flow. The test induced an increase (P < 0.01) in blood pressure, heart rate, endothelin-1 and catecholamine levels, whereas it did not change the low basal levels of nitric oxide. In healthy subjects (n = 20) the test significantly (P < 0.01) decreased endothelin-1 without affecting nitric oxide. The low basal levels of nitric oxide and the high plasma concentration of endothelin-1 after psychological stress cannot be explained by an impaired release from the limited ischemic lesions alone. This suggests a diffuse microvascular derangement that aggravates the course of peripheral microvascular ischemic lesions.     

APP substitutions V715F and L720P alter PS1 conformation and differentially affect Abeta and AICD generation

The 37-43 amino acid Abeta peptide is the principal component of beta-amyloid deposits in Alzheimer's disease (AD) brain, and is derived by serial proteolysis of the amyloid precursor protein (APP) by beta- and gamma-secretase. gamma-Secretase also cleaves APP at Val50 in the Abeta numbering (epsilon cleavage), resulting in the release of a fragment called APP intracellular domain (AICD). The aim of this study was to determine whether amino acid substitutions in the APP transmembrane domain differentially affect Abeta and AICD generation. We found that the APPV715F substitution, which has been previously shown to dramatically decrease Abeta40 and Abeta42 while increasing Abeta38 levels, does not affect in vitro generation of AICD. Furthermore, we found that the APPL720P substitution, which has been previously shown to prevent in vitro generation of AICD, completely prevents Abeta generation. Using a fluorescence resonance energy transfer (FRET) method, we next found that both the APPV715F and APPL720P substitutions significantly increase the distance between the N- and C-terminus of presenilin 1 (PS1), which has been proposed to contain the catalytic site of gamma-secretase. In conclusion, both APPV715F and APPL720P change PS1 conformation with differential effects on Abeta and AICD production.     

Nociceptin/orphanin FQ prevents ethanol-induced gastric lesions in the rat

Nociceptin/orphanin FQ (N/OFQ), the endogenous ligand of the NOP receptor, exerts a variety of effects on the gastrointestinal tract. The present study was aimed at evaluating the possible implication of N/OFQ in the maintenance of gastric mucosal integrity. N/OFQ was given either centrally or peripherally 30 min prior to intragastric administration (i.g.) of 1 ml/rat of ethanol (either 25% or 50%, v/v), which produces macroscopically visible gastric lesions. Intracerebroventricular (i.c.v.) injection of 2 microg/rat of N/OFQ significantly reduced lesions caused by 50% ethanol, while 1 microg/rat was enough to significantly reduce lesions caused by 25% ethanol. Intracerebroventricular injection of 5 microg/rat of the selective NOP receptor antagonist, UFP-101, completely reversed the protective effect of N/OFQ, 1 or 4 microg/rat against 25% or 50% ethanol, respectively. The intraperitoneal (i.p.) injection of N/OFQ produced a significant reduction of lesions induced by 50% ethanol, the peak effect being observed at 10 microg/kg. Intraperitoneal pretreatment with UFP-101, 120 microg/kg, completely abolished the protective effect of peripherally injected N/OFQ. Therefore, N/OFQ acts both centrally and peripherally as a protective agent against ethanol-induced gastric lesions, and its effect is mediated by NOP receptors.     

Carbonic anhydrase inhibitors. Zonisamide is an effective inhibitor of the cytosolic isozyme II and mitochondrial isozyme V: solution and X-ray crystallographic studies

The antiepileptic drug zonisamide was considered to act as a weak inhibitor of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1) (with a K(I) of 4.3 microM against the cytosolic isozyme II). Here we prove that this is not true. Indeed, testing zonisamide in the classical assay conditions of the CO2 hydrase activity of hCA II, with incubation times of enzyme and inhibitor solution of 15 min, a K(I) of 10.3 microM has been obtained. However, when the incubation between enzyme and inhibitor was prolonged to 1 h, the obtained K(I) was of 35.2 nM, of the same order of magnitude as that of the clinically used sulfonamides/sulfamates acetazolamide, methazolamide, ethoxzolamide and topiramate (K(I)s in the range of 5.4-15.4 nM). The inhibition of the human mitochondrial isozyme hCA V with these compounds has been also tested by means of a dansylamide competition binding assay, which showed zonisamide and topiramate to be effective inhibitors, with K(I)s in the range of 20.6-25.4 nM. The X-ray crystal structure of the adduct of hCA II with zonisamide has also been solved at a resolution of 1.70 A, showing that the sulfonamide moiety participates in the classical interactions with the Zn(II) ion and the residues Thr199 and Glu106, whereas the benzisoxazole ring is oriented toward the hydrophobic half of the active site, establishing a large number of strong van der Waals interactions (<4.5 A) with residues Gln92, Val121, Phe131, Leu198, Thr200, Pro202.     

Nigrostriatal dopaminergic deficits and hypokinesia caused by inactivation of the familial Parkinsonism-linked gene DJ-1

The manifestations of Parkinson's disease are caused by reduced dopaminergic innervation of the striatum. Loss-of-function mutations in the DJ-1 gene cause early-onset familial parkinsonism. To investigate a possible role for DJ-1 in the dopaminergic system, we generated a mouse model bearing a germline disruption of DJ-1. Although DJ-1(-/-) mice had normal numbers of dopaminergic neurons in the substantia nigra, evoked dopamine overflow in the striatum was markedly reduced, primarily as a result of increased reuptake. Nigral neurons lacking DJ-1 were less sensitive to the inhibitory effects of D2 autoreceptor stimulation. Corticostriatal long-term potentiation was normal in medium spiny neurons of DJ-1(-/-) mice, but long-term depression (LTD) was absent. The LTD deficit was reversed by treatment with D2 but not D1 receptor agonists. Furthermore, DJ-1(-/-) mice displayed hypoactivity in the open field. Collectively, our findings suggest an essential role for DJ-1 in dopaminergic physiology and D2 receptor-mediated functions.     

Novel anellated pyrazoloquinolin-3-ones: synthesis and in vitro BZR activity

A series of pyrazolo[4,3-c]pyrrolo[3,2-f]quinolin-3-one derivatives 6, 7a-c, 8a,b, 9a,b and 10-12 were synthesized as modified pyrazoloquinolinone analogs (PQs) and evaluated for their ability to inhibit radioligand to central and peripheral benzodiazepine receptors (BZRs) and their effect on GABA(A) alpha1beta2gamma2L receptors expressed in Xenopus laevis oocytes. Multistep synthesis starting from 5-nitroindole, via the Gould-Jacobs reaction to the quinoline nucleus, yielded key intermediates 9-chloro-3H-pyrrolo[3,2-f]quinoline-8-carboxylates. The reaction of the latter with methyl-hydrazine and various phenyl-hydrazines furnished the final compounds. In order to confirm the expected tetracyclic 2-substituted-2H-pyrazolopyrroloquinolin-3-one structure, IR spectrophotometric, mono-1H and 13C and bi-dimensional spectrometric and HRMS analyses were carried out: all compounds were found to be 2-substituted 3-keto tautomers; compound 6 only differed because it turned out to be 1-methyl-2H-pyrazolo[4,3-c]pyrrolo[3,2-f]quinolin-3-olo. The results of this work are consistent with those previously reported for PQs: 7-9 show high potency in displacing specific [3H]flunitrazepam from its receptor site; no compound was active in inhibiting the binding of [3H]PK 11195. They all act as antagonists at central BZR.     

Fra1 activity in the frog, Rana esculenta, testis: a new potential role in sperm transport

Using an anti-Fos family member antibody, we have previously described in Rana esculenta testis the presence of a nuclear, 43 kDa protein that we hypothesized to be Fra1. With the assistance of an antibody against Fra1 that does not cross-react with other Fos family members, here we report data on Fra1 expression, localization, and putative activity in Rana esculenta testis during its annual reproductive cycle. Western blot analysis confirms that the nuclear, 43 kDa protein is Fra1. Immunocytochemistry validates the Western blot results and shows cytoplasmic and nuclear immunostaining of Fra1 in peritubular myoid cells, efferent ducts, and blood vessels. We report for the first time in a vertebrate, experimental evidence showing that the expression of Fra1 is related to peritubular myoid cells during sperm transport from the tubular compartment to efferent ducts.