Pharmacokinetics and safety assessments of high-dose and 4-week treatment with S-3304, a novel matrix metalloproteinase inhibitor, in healthy volunteers.

AIMS: To investigate the tolerability, safety and pharmacokinetics of S-3304 in healthy volunteers treated with high doses of S-3304 for 28 days. METHODS: Thirty-two healthy volunteers were recruited. Four male and four female subjects were allocated to one of four doses (800 mg, 1600 mg, 2400 mg and 3200 mg). At each dose six volunteers took active medication and two volunteers took placebo in a double-blind fashion. Volunteers took a single dose on days 1 and 28 for pharmacokinetic purposes, and took twice daily doses from day 3-27. The pharmacokinetics of S-3304 and its hydroxy metabolites were evaluated. Tolerance was based on subjective adverse events, clinical examination, vital signs, ECG and laboratory tests including haematology and biochemistry profiles using CTC grading. RESULTS: Doses up to 2400 mg twice daily were generally well tolerated. At 3200 mg twice daily, five volunteers including one randomized to placebo were withdrawn from treatment mainly due to alanine aminotransferase (ALT) elevation. C(max) of S-3304 on day 1, whose geometric mean and 95% confidence interval were 66.3 microg ml(-1) (48.8, 90.0) for 800 mg, 82.6 microg ml(-1) (69.3, 98.6) for 1600 mg, 89.5 microg ml(-1) (79.5, 100.7) for 2400 mg, and 110.5 microg ml(-1) (88.9, 137.7) for 3200 mg, respectively, was correlated with the log-transformed peak ALT (P < 0.0001 for male and P = 0.048 for female volunteers). CONCLUSIONS: In healthy volunteers the maximum tolerated dose of S-3304 was 2400 mg twice daily. ALT elevation was the most frequent dose-limiting factor and was correlated with C(max) on day 1.

Prostaglandin E2 rescues cortical neurons from amyloid beta protein-induced apoptosis.

Cerebrospinal fluid prostaglandin E(2) (PGE(2)) levels are elevated in patients with Alzheimer's disease (AD), suggesting an involvement of PGE(2) in the neurodegeneration. AD is characterized by deposits of amyloid beta protein (Abeta) in various regions of the brain, e.g. the cerebral cortex. In the present study, we investigated the effects of PGE(2) on neuronal survival in primary cultures of rat cortical neurons. PGE(2) had no effect on neuronal cell viability or its morphology. Therefore, we examined the synergistic effects of PGE(2) with Abeta, a neurotoxin. Abeta caused neuronal cell death via apoptosis. PGE(2) significantly suppressed Abeta neurotoxicity, but did not promote the neurotoxicity. Furthermore, PGE(2) ameliorated Abeta-induced apoptotic features such as the condensation of chromatin and the fragmentation of DNA. Abeta increased the influx of Ca(2+) into neurons before cell death. Nimodipine, an inhibitor of the L-type voltage-sensitive calcium channel (L-VSCC), significantly reduced Abeta-potentiated Ca(2+) uptake. On the other hand, there was no effect on the Abeta-induced Ca(2+) influx by an N-VSCC blocker or P/Q-VSCC blockers. Moreover, the inhibitor of L-VSCC suppressed Abeta-induced neuronal cell death, whereas neither an N-VSCC blocker nor P/Q-VSCC blockers affected the neurotoxicity of Abeta. PGE(2) also suppressed the Abeta-induced Ca(2+) influx in a concentration-dependent manner. This study demonstrated that PGE(2) rescues cortical neurons from Abeta-induced apoptosis by reducing Ca(2+) influx in the primary culture. Furthermore, the present study suggested that the inhibition of L-VSCC contributes to the neuroprotective effect of PGE(2).

Effects of endothelin B receptor agonists on amyloid beta protein (25-35)-induced neuronal cell death.

Endothelin (ET), a vasoconstrictive peptide, acts as an anti-apoptotic factor, and endothelin receptor B (ET(B) receptor) is associated with neuronal survival in the brain. In the Alzheimer's disease (AD) brain, accumulation of amyloid beta protein (Abeta) is thought to cause neuronal cell death via apoptosis. In the present study, we investigated effects of ET(B) receptor agonists on Abeta-induced neuronal cell death. In primary cultures of rat cortical neurons, Abeta(25-35) caused neuronal cell death in a concentration- and time-dependent manner. Abeta(25-35)-induced neuronal cell death was accompanied by chromatin condensation and DNA fragmentation, exhibiting apoptotic features. ET-3 and IRL-1620, ET(B) receptor agonists, significantly prevented neurons from undergoing Abeta(25-35)-induced cell death. Prior to cell death, Abeta increased concentration of intracellular Ca(2+) ([Ca(2+)](i)). Nimodipine, an L-type voltage-sensitive Ca(2+) channel (L-VSCC) blocker, suppressed the Abeta-induced Ca(2) influx, and attenuated Abeta-induced neuronal apoptosis. On the other hand, omega-conotoxin GIVA, an N-type VSCC blocker and omega-conotoxin MVIIC and omega-agatoxin IVA, P/Q-type VSCC blockers, had no effect. ET-3 and IRL-1620 significantly blocked Abeta(25-35)-induced Ca(2) influx. Furthermore, BQ788, an ET(B) receptor antagonist, inhibited both an anti-apoptotic effect and an L-VSCC-inactivating effect of ET(B) receptor agonists. In conclusion, ET(B) receptor agonists exhibit a protective effect against neurotoxicity of Abeta. Furthermore, these agonists appear to act as anti-apoptotic factors by blocking of L-VSCCs.