Tetrahydro-N, N-dimethyl-2, 2-diphenyl-3-furanmethanamine hydrochloride (ANAVEX2-73) binds to muscarinic acetylcholine and sigma(1) (σ(1)) receptors with affinities in the low micromolar range. We characterized its anti-amnesic and neuroprotective potentials in pharmacological and pathological amnesia models. Spatial working memory was evaluated using spontaneous alternation in the Y-maze and non-spatial memory using passive avoidance procedures. ANAVEX2-73 (0.01-3.0 mg/kg i.p.) alleviated the scopolamine- and dizocilpine-induced learning impairments. ANAVEX2-73 (300 µg/kg) also reversed the learning deficits in mice injected with Aβ(25-35) peptide, a non-transgenic Alzheimer's disease model. When the drug was injected simultaneously with Aβ(25-35), 7 days before the tests, it blocked the appearance of learning impairments. This protective activity was confirmed since ANAVEX2-73 blocked the Aβ(25-35)-induced oxidative stress in the hippocampus. This effect was differentially sensitive to the muscarinic receptor antagonist scopolamine or the σ(1) protein antagonist BD1047, confirming the mixed muscarinic/σ(1) pharmacological action. Finally, its unique demethyl metabolite, ANAVEX19-144, was also effective and ANAVEX2-73 presented a longer duration of action, effective 12 h before Aβ(25-35), than its related compound ANAVEX1-41. The neuroprotective activity of ANAVEX2-73, its mixed cholinergic/σ(1) activity, its low active dose range and its long duration of action together reinforce its therapeutic potential in Alzheimer's disease.

The antiamnesic and neuroprotective activities of the new aminotetrahydrofuran derivative tetrahydro-N,N-dimethyl-5,5-diphenyl-3-furanmethanamine hydrochloride (ANAVEX1-41), a nonselective muscarinic receptor ligand and s 1 protein activator, were examined in mice injected intracerebroventricularly with amyloid b [25][26][27][28][29][30][31][32][33][34][35] ) peptide (9 nmol). Ab 25-35 impaired significantly spontaneous alternation performance, a spatial working memory, and passive avoidance response. When ANAVEX1-41 (1-1000 mg/kg i.p.) was administered 7 days after Ab 25-35 , ie, 20 min before the behavioral tests, it significantly reversed the Ab 25-35 -induced deficits, the most active doses being in the 3-100 mg/kg range. When the compound was preadministered 20 min before Ab 25-35 , ie, 7 days before the tests, it prevented the learning impairments at 30-100 mg/kg. Morphological analysis of corticolimbic structures showed that Ab 25-35 induced a significant cell loss in the CA1 pyramidal cell layer of the hippocampus that was prevented by ANAVEX1-41 (100 mg/kg). Increased number of glial fibrillary acidic protein immunopositive cells in the retrosplenial cortex or throughout the hippocampus revealed an Ab 25-35 -induced inflammation that was prevented by ANAVEX1-41. The drug also prevented the parameters of Ab 25-35 -induced oxidative stress measured in hippocampus extracts, ie, the increases in lipid peroxidation and protein nitration. ANAVEX1-41, however, failed to prevent Ab 25-35 -induced caspase-9 expression. The compound also blocked the Ab 25-35 -induced caspase-3 expression, a marker of apoptosis. Both the muscarinic antagonist scopolamine and the s 1 protein inactivator BD1047 prevented the beneficial effects of ANAVEX1-41 (30 or 100 mg/kg) against Ab 25-35 -induced learning impairments, suggesting that muscarinic and s 1 targets are involved in the drug effect. A synergic effect could indeed account for the very low active doses measured in vivo. These data outline the therapeutic potential of ANAVEX1-41 as a neuroprotective agent in Alzheimer's disease.