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Krx-0501 reduces cognitive deficits in a saporin mouse model of Alzheimer’s disease

Lowrance SA, Matchynski JJ, Rossignol J, Dekorver N, Fink K, Salibi P, Dunbar GL (2010) Krx-0501 reduces cognitive deficits in a saporin mouse model of Alzheimer’s disease. Neuroscience 2010 Abstracts 856.8/I14. Society for Neuroscience, San Diego, CA.

Summary: Alzheimer’s disease (AD) is a progressive neurodegenerative disease marked by memory loss and dysfunction of cholinergic neurons. Neurotrophic factors, like nerve growth factor (NGF), have shown to improve cognitive function in AD patients. The inability of NGF to cross the blood brain barrier (BBB) and painful side effects have caused serious concerns over its future use as a treatment. Substituted pyrimidines, such as KRX-0501 (KRX; Keryx Biopharmaceuticals, New York, NY) on the other hand, readily cross the BBB and exert beneficial neurotrophic-like effects in vivo. In this study KRX was administered daily to mice that were given intra-cerebroventricular injections of mu p-75 Saporin (SAP; Advanced Targeting Systems, San Diego, CA) or vehicle (phosphate buffered saline). KRX treatment began at seven weeks of age and continued for 32 days. Doses were set at 10, 15, and 20mg/kg respectively. Animals were tested for cognitive impairment using the Morris water maze (MWM) task, object recognition (OR) and place recognition (PR) tasks while motor deficits were tested using MWM swim speed, rotarod (RR) and the open field (OF) tasks. On day 33 of KRX treatment, mice were sacrificed by transcardial perfusion. In a second experiment, mice received SAP or vehicle surgery and were sacrificed for enzyme-linked immunosorbent assay (ELISA) analysis. MWM results revealed significantly lower escape latencies of control animals relative to SAP animals. In addition mice treated with the low and middle doses of KRX displayed decreased escape latency on the MWM. In the OR task, only mice in the highest treatment group performed significantly above chance levels. No between group differences were seen in the PR task, swim speed, latency to fall from the RR, and distance travelled in the OF. Immunohistochemistry (IHC) using the glial fibrillary acidic protein antibody indicated that astrocyte activation took place primarily around the surgical injection sites. IHC labeling against choline-acetyltransferase revealed a significant decrease in cholinergic neurons of the medial septum. Finally, ELISA protein analysis of midbrain sections revealed that the KRX treatments did not increase levels of endogenous NGF. These results show that SAP injections produced a reproducible destruction of cholinergic neurons, accompanied by memory deficits in the MWM, in the absence of motoric deficits. The KRX treatment attenuated memory deficits, despite unabated cholinergic cell loss in the medial septum, and did so without affecting levels of endogenous NGF.

Related Products: mu p75-SAP (Cat. #IT-16)