Affiliations: [a] Department of Pharmacology, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China | [b] Departments of Behavioral Medicine & Psychiatry and Physiology & Pharmacology, West Virginia University Health Sciences Center, Morgantown, WV, USA | [c] Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
Correspondence:
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Correspondence to: Jiangping Xu, Department of Pharmacology, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China. Tel.: +86 20 61648236; Fax: +86 02 61648236; E-mail: jpx@smu.edu.cn; Han-Ting Zhang, Department of Behavioral Medicine & Psychiatry, West Virginia University Health Sciences Center, PO Box 9137, Morgantown, WV 26506 USA. Tel: +1 304 293 1488; Fax: +1 304 293 1634; E-mail: hzhang@hsc.wvu.edu.
Abstract: Phosphodiesterase-4 (PDE4) inhibitors enhance memory, increase hippocampal neurogenesis, and reverse amyloid-β (Aβ)-induced memory deficits. Here, we examined whether long-form PDE4D knockdown by lentiviral RNA construct containing a specific microRNA/miRNA-mir hairpin structure (4DmiRNA) reversed memory impairment caused by amyloid-β1-42 (Aβ42) in mice using the Morris water maze (MWM) and novelty object recognition tests. Western blotting analysis was used to assess protein levels of cAMP response element-binding protein (CREB, unphosphorylated and phosphorylated [pCREB]), brain-derived neurotrophic factor (BDNF), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and nuclear factor-κB (NF-κB) to explore the neurochemical mechanisms. Aggregated Aβ42 (0.5 μg/side) bilaterally infused in dentate gyrus decreased cAMP levels (p < 0.01) and produced memory deficits in the MWM (p < 0.01) and object recognition tests (p < 0.01). Microinfusions of lentiviruses resulted in downregulated expression of PDE4D4 and 4D5 proteins and reversed Aβ42-induced cAMP decline (p < 0.05) and memory deficits. Treatment also concomitantly increased pCREB (p < 0.05) and BDNF (p < 0.01) and reduced IL-1β (p < 0.05), TNF-α (p < 0.01), and NF-κB (p65) (p < 0.05) in the hippocampus of Aβ42-challenged mice. These results suggest that long-form PDE4D knockdown may offer a promising treatment for memory loss associated with Alzheimer's disease.
