Figure 1

Experimental protocol used to assess the anti-Alzheimer's disease properties of caprospinol. The procedure used to induce the Alzheimer's disease (AD) histopathological phenotype in rats has previously been described [35]. The phenotype was induced by administering a solution containing FeSO₄ (1 mM), Aβ_1-42 (15 μM), and buthionine sulfoximine (12 mM) at pH = 5.1 ± 0.1 into the left ventricle of male Long-Evans rats via an osmotic micropump (2ML4; Durect Corp., Cupertino, CA, USA) over 4 weeks. This solution was named ferrous amyloid buthionine (FAB). At the end of the 4 weeks, the pump was replaced with a new one that contained the same solution for an additional 4-week infusion. In a subset of animals, caprospinol was administered intraperitoneally (10 mg/kg/day) during the final 4 weeks of FAB infusion, starting the treatment at a moment when the animals manifested the clinical phenotype. At the end of the 8-week period, cognitive processes were assessed using a Morris water maze task. (A) Histopathological features of the FAB rat at week 4. Hyperphosphorylated tau protein (clone AT-8) in the hippocampus. (B) Campbell-Switzer silver staining revealing vascular amyloidogenesis. (C) Campbell-Switzer silver staining revealing amyloid plaque containing neuritic debris in the cortex. (D) Cortical neurodegenerative processes revealed by De Olmos silver staining. (E) Amyloid deposits revealed in the hippocampus by Campbell-Switzer silver staining. (F,G) Histopathological features of the FAB rat at week 8 and the effect of caprospinol: Campbell-Switzer silver staining of amyloid deposits in the hippocampus of untreated (F) and caprospinol-treated (G) FAB rats. (H,I) Degenerating neurons labeled with FluoroJade C in the hippocampus of untreated (H) and caprospinol-treated (I) FAB rats. (J) Assessment of FAB rat cognitive performance in the Morris water maze task at week 8. FAB rats displayed dramatic cognitive impairment as shown by the much lower score obtained in the probe trial compared to the control rats (26.06 ± 1.49, n = 6, versus 36.81 ± 2.48, n = 6, P = 0.004). FAB-infused rats chronically treated with caprospinol at 10 mg/kg/day displayed cognitive performance equivalent to that observed in the control group (36.56 ± 2.09, n = 10, versus 36.81 ± 2.48, n = 6), demonstrating that chronic caprospinol treatment eliminated the cognitive impairment observed in the FAB-infused rats (36.56 ± 2.09, n = 10, versus 26.06 ± 1.49, n = 6, P = 0.002). (K) In addition, caprospinol-treated FAB rats crossed the platform more times than the untreated group. Parts of this figure were reprinted with permission from [49] and [63].