Loss of MAP function leads to hippocampal synapse loss and deficits in the Morris Water Maze with aging

• Published in: The Journal of neuroscience Vol. 34; no. 21; pp. 7124 - 7136
• Main Authors: Ma, Qiu-Lan, Zuo, Xiaohong, Yang, Fusheng, Ubeda, Oliver J, Gant, Dana J, Alaverdyan, Mher, Kiosea, Nicolae C, Nazari, Sean, Chen, Ping Ping, Nothias, Fatiha, Chan, Piu, Teng, Edmond, Frautschy, Sally A, Cole, Greg M
• Format: Journal Article
• Language: English
• Published: United States Society for Neuroscience 21.05.2014
• Subjects: Aging - drug effects; Aging - genetics; Aging - pathology; Alzheimer Disease - complications; Alzheimer Disease - genetics; Alzheimer Disease - pathology; Animals; Disease Models, Animal; Docosahexaenoic Acids - administration & dosage; Gene Expression Regulation - drug effects; Gene Expression Regulation - genetics; Hippocampus - drug effects; Hippocampus - pathology; Learning Disorders - diet therapy; Learning Disorders - etiology; Life Sciences; Maze Learning - physiology; Mice; Mice, Inbred C57BL; Mice, Knockout; Movement Disorders - diet therapy; Movement Disorders - etiology; Neurons and Cognition; Psychomotor Performance - physiology; Reaction Time - drug effects; Substantia Nigra - metabolism; Substantia Nigra - pathology; Synapses - drug effects; Synapses - genetics; Synapses - metabolism; tau Proteins - deficiency; Thioctic Acid - administration & dosage; synaptic markers; tau; MAPs; knock-out; Alzheimer's disease; Morris Water Maze
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.3439-13.2014

Hyperphosphorylation and accumulation of tau aggregates are prominent features in tauopathies, including Alzheimer's disease, but the impact of loss of tau function on synaptic and cognitive deficits remains poorly understood. We report that old (19-20 months; OKO) but not middle-aged (8-9 months; MKO) tau knock-out mice develop Morris Water Maze (MWM) deficits and loss of hippocampal acetylated α-tubulin and excitatory synaptic proteins. Mild motor deficits and reduction in tyrosine hydroxylase (TH) in the substantia nigra were present by middle age, but did not affect MWM performance, whereas OKO mice showed MWM deficits paralleling hippocampal deficits. Deletion of tau, a microtubule-associated protein (MAP), resulted in increased levels of MAP1A, MAP1B, and MAP2 in MKO, followed by loss of MAP2 and MAP1B in OKO. Hippocampal synaptic deficits in OKO mice were partially corrected with dietary supplementation with docosahexaenoic acid (DHA) and both MWM and synaptic deficits were fully corrected by combining DHA with α-lipoic acid (ALA), which also prevented TH loss. DHA or DHA/ALA restored phosphorylated and total GSK3β and attenuated hyperactivation of the tau C-Jun N-terminal kinases (JNKs) while increasing MAP1B, dephosphorylated (active) MAP2, and acetylated α-tubulin, suggesting improved microtubule stability and maintenance of active compensatory MAPs. Our results implicate the loss of MAP function in age-associated hippocampal deficits and identify a safe dietary intervention, rescuing both MAP function and TH in OKO mice. Therefore, in addition to microtubule-stabilizing therapeutic drugs, preserving or restoring compensatory MAP function may be a useful new prevention strategy.