Soft-diet feeding decreases dopamine release and impairs aversion learning in Alzheimer model rats.
To examine the effects of soft-diet feeding on the dopaminergic system in a model rat for Alzheimer's disease (AD), we measured dopamine release in the hippocampus using a microdialysis approach and assessed learning ability and memory using step-through passive avoidance tests. Furthermore, we immunohistochemically examined the ventral tegmental area (VTA), which is the origin of hippocampal dopaminergic fibers using tyrosine hydroxylase (TH), a marker enzyme for the dopaminergic nervous system. Feeding a soft diet decreased dopamine release in the hippocampus and impaired learning ability and memory in AD model rats in comparison with rats fed a hard diet; however, TH-immunopositive profiles in the VTA seemed not to be notably different between rats fed a soft diet and those fed a hard diet. These observations suggest that soft-diet feeding enhances the impairment of learning ability and memory through the decline of dopamine release in the hippocampus in AD rats.
Kushida
S
S
Division of Prosthetics, Department of Oral & Maxillofacial Rehabilitation, Kanagawa Dental College, Yokosuka 238-8580, Japan.
Kimoto
K
K
Hori
N
N
Toyoda
M
M
Karasawa
N
N
Yamamoto
T
T
Kojo
A
A
Onozuka
M
M
D000544:Alzheimer Disease / Q000139:chemically induced / Q000150:complications; D016229:Amyloid beta-Peptides; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D004032:Diet / Q000379:methods*; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism*; D004563:Electrochemistry / Q000379:methods; D006624:Hippocampus / Q000378:metabolism; D007859:Learning Disabilities / Q000209:etiology / Q000473:pathology; D008297:Male; D017551:Microdialysis / Q000379:methods; D010446:Peptide Fragments; D051381:Rats; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D017557:Ventral Tegmental Area / Q000378:metabolism
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine