p38 MAPK has been implicated in the regulation of promflammatory cytokines and apoptosis in vitro. To understand its role in neurodegeneration, we determined the time course and localization of the dually phosphorylated active form of p38 MAPK in hippocampus after global forebrain ischemia. Phosphorylated p38 MAPK and mitogen-activated protein kinase-activated protein 2 activity increased over 4 days after ischemia. Phosphorylated p38 MAPK immunoreactivity was observed in microglia in regions adjacent to, but not in, the dying CAl neurons. In contrast, neither c-Jun N-terminal kinase 1 nor p42/p44M~activity was altered after ischemia. These results provide the first evidence for localization of activated p38 MAPK in the CNS and support a role for p38 MAPK in the microglial response to stress.

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Further exploration of the cycloalkanol ethylamine scaffold, of which venlafaxine ( 1) is a member, was undertaken to develop novel and selective norepinephrine reuptake inhibitors (NRIs) for evaluation in a variety of predictive animal models. These efforts led to the discovery of a piperazine-containing analogue, 17g (WY-46824), that exhibited potent norepinephrine reuptake inhibition, excellent selectivity over the serotonin transporter, but no selectivity over the dopamine transporter. Synthesis and testing of a series of cyclohexanol ethylpiperazines identified ( S)-(-)- 17i (WAY-256805), a potent norepinephrine reuptake inhibitor (IC 50 = 82 nM, K i = 50 nM) that exhibited excellent selectivity over both the serotonin and dopamine transporters and was efficacious in animal models of depression, pain, and thermoregulatory dysfunction.

In vitro studies indicatethat p 42/p44MAPK phosphorylate both nuclear and cytoplasmic proteins. However, the functional targets of p42/p44MA~< activation in vivo remain unclear. To address this question, we localized activated p42/p44M~in hippocampus and cortex and determined their signaling effects after electroconvulsive shock treatment (ECT) in rats. Phosphorylated p42/ p44MAPK content increased in the cytoplasm of hippocampal neurons in response to ECT. Consistent with this cytoplasmic localization, inhibition of ECT-induced p42/ p44MAPK activation by the extracellular signal-regulated kinase kinase inhibitor PD098059 blocked phosphorylation of the cytoplasmic protein microtubule-associated protein 2c (MAP2c), but failed to inhibit the induction of the nuclear protein c-Fos in response to ECT. In contrast to hippocampal neurons, cortical neurons exhibited an increase in amount of phosphorylated p42/p44MAPK in both the nucleus and cytoplasm after ECT. Accordingly, PD098059 blocked the induction of Fos-like immunoreactivity in the nuclei of cortical neurons as well as MAP2c phosphorylation in the cytoplasm. Our data indicate that both nuclear and cytoplasmic substrates can be activated by p42/p44M~in vivo. However, the functional targets of p42/p44MAPK signaling depend on the precise location of p42/p44MAR< within different subcellular compartments of brain regions. These results indicate unique functional pathways of p42/p44M~<~mediated signal transduction within different brain regions in vivo. Key Words: Signal transduction -Erk2-Mitogen-activated protein kinase-Hippocampus-Microtubule-associated protein 2-c-Fos -Phosphorylation-Neuronal function-Elki -Cyclic AMP response element binding protein.

Sequential structural modifications of the aryloxypropanamine template (e.g., atomoxetine, 2) led to a novel series of 1-(3-amino-2-hydroxy-1-phenyl propyl)-1,3-dihydro-2H-benzimidazol-2-ones as selective norepinephrine reuptake inhibitors (NRIs). In general, this series of compounds potently blocked the human norepinephrine transporter (hNET) while exhibiting selectivity at hNET against both the human serotonin (hSERT) and dopamine transporters (hDAT). Numerous compounds (e.g., 19-22) had low nonamolar hNET potency with IC(50) values of 7-10 nM and excellent selectivity (>500 fold) at hNET over hSERT and hDAT. Several compounds, such as 20 and 22, were tested in a telemetric rat model of ovariectomized-induced thermoregulatory dysfunction and were efficacious at oral doses of 3 mg/kg in reducing the tail skin temperature. In addition, compound 20 was also studied in the rat hot plate and spinal nerve ligation (SNL) models of acute and neuropathic pain, respectively, and was orally efficacious at doses of 3-10 mg/kg.

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Efforts to identify new selective and potent norepinephrine reuptake inhibitors (NRIs) for multiple indications by structural modification of the previous 3-(arylamino)-3-phenylpropan-2-olamine scaffold led to the discovery of a novel series of 1-(indolin-1-yl)-1-phenyl-3-propan-2-olamines (9). Investigation of the structure-activity relationships revealed that small alkyl substitution at the C3 position of the indoline ring enhanced selectivity for the norepinephrine transporter (NET) over the serotonin transporter (SERT). Several compounds bearing a 3,3-dimethyl group on the indoline ring, 9k, 9o,p, and 9s,t, exhibited potent inhibition of NET (IC(50) = 2.7-6.5 nM) and excellent selectivity over both serotonin and dopamine transporters. The best example from this series, 9p, a potent and highly selective NRI, displayed oral efficacy in a telemetric rat model of ovariectomized-induced thermoregulatory dysfunction, a mouse p-phenylquinone (PPQ) model of acute visceral pain, and a rat spinal nerve ligation (SNL) model of neuropathic pain.

No abstract