Synthetic catalytic scavengers of reactive oxygen species (ROS) may have broad clinical applicability. In previous papers, two salen-manganese complexes, EUK-8 and EUK-134, had superoxide dismutase (SOD) and catalase activities and prevented ROS-associated tissue injury. This study describes two series of salen-manganese complexes, comparing catalytic ROS scavenging properties and cytoprotective activities. The compounds vary widely in ability to scavenge hydrogen peroxide, with this activity most influenced by salen ring alkoxy substitution and aromatic bridge modifications. In contrast, all compounds show comparable SOD activities. The most active alkoxy-substituted catalase mimetics protected cultured cells from hydrogen peroxide, and a subset of these were also neuroprotective in a rodent stroke model. Thus, structural modification of the prototype EUK-8 yields compounds with enhanced catalase activity and, in turn, biological effectiveness. This supports the concept that salen-manganese complexes represent a class of SOD and, in particular, catalase mimetics potentially useful against ROS-associated diseases.

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It is well established that inflammation and oxidative stress are key components of the pathology of Alzheimer's disease (AD), but how early in the pathological cascade these processes are involved or which specific molecular components are key, has not been fully elucidated. This paper describes the pharmacological approach to understand the molecular components of inflammation and oxidative stress on the activation of microglial cells and neuronal cell viability. We have shown that activation of microglia with the 42-amino-acid form of the ϐ-amyloid peptide (Aϐ42) activates the production of cyclooxygenase-2, the inducible form of nitric oxide synthase and tumour necrosis factor-α and there appears to be little interactive feedback between these three mediators. Moreover, we explore the effects of a series of salen-manganese complexes, EUK-8, -134 and -189, which are known to possess both superoxide and catalase activity. These compounds are able to protect cells from insults produced by hydrogen peroxide or peroxynitrite. Moreover, EUK-134 was also able to limit the output of prostaglandin E2 from activated microglial cells. The mechanisms underlying these effects are discussed. Together, these data support a pivotal role for oxidative stress and inflammation as key mediators of the pathological cascade in AD and provide some ideas about possible therapeutic targets.

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Muscarhic acetylcholine receptors (mAChRs) are involved in synaptic plasticity. In a screen designed to identify genes involved in mAChR signaling. w e found I 1 genes that were readily activated by mAChR These included the transcription factors Egr-I. Egr-2, Egr-3, c-jun, jun-D, and GOS3, the growth regulator hCyr61, the signaling factors NGFi-B, ETRIOl, and Gig-2 as well as the acetylcholine cstcrasc gene (AChE). hCyr61 encodes a secretory protein with groarrh-promoting functions mediated by interactions with inregrins and heparin-containing components of the extracellular matrix. Gig-2 is a novel gene with similarities to serine-threonine kinases, and with potential targeting to the secretory pathway. Both mAChR over-expressing 293 lines and primary cortical neurons responded to receptor stimulation with increased expression of both genes within 15 minutes, attained a maximum after 1 hour with sustained high expression for 4 hours. Receptor stimulation also triggered gene expression in the presence of cycloheximide, indicating that hCyr61 and gig-2 arc immediate urly genes. In vivo experiments with pilocarpine strongly induced gig-2 expression in neurons of several layers of the brain cortex, the hippoumpal CAI region, and the puumcn. Increased expression of both hCyr61 and gig-2 was coupled to mAChRs by PKC. whereas CAMP failed to affect expression. We also observed that mAChR rudily increased both Egr-l transcription and nuclear concentrations of Egr-l protein; with subsequent strong activation of transcription from the human AChE promoter, and expression of the AChE gene.Our data show that multiple immediate-urly genes arc under the control of mAChRs, and they suggest that both hCyr61 and gig-2 play important roles in coupling receptor stimulation to long-term neuronal responses. The results also suggest a feedback mechanism by which increases in cholinergic transmission are limited by upregulated AChE expression, and accelerated breakdown of ACh at the cholincrgic synapses.Evidence that aberrations in oxidative signalling and glial inflammatory pathways are features of the pathology of Alzheimer's disease (AD) remains undisputed. Data generated over the past 15 yCars have consistently reported the presence of a variety of inflammatory proteins in the brain of A D patients taken post-mortem (see McGccr & McGecr, 1995). There is also considerable evidence for damage caused by free radicals that arc produced by alterations in the homeostatic mechanisms controlling oxygen utilisation (see Smith et al, 1999). However. one of the key hurdles for research continues to be able to address whether oxidative stress andlor inflammation are early aetiological factors that contribute to the devclopment of the progressive pathology of the disease and thus provide specific targets for drug intervention. This talk will describe the utility of pharmacological tools to probe mechanisms of oxidative stress and inflammation, both in vitro and in vivo. The data to be presented support the premise that specific mediators of infl...