Impairment of spatial memory in kaolin-induced hydrocephalic rats is associated with changes in the hippocampal cholinergic and noradrenergic contents.
We investigated the relationship between the degree of spatial memory impairment in an 8-arm radial maze and the changes in the contents of acetylcholine (ACh) and noradrenaline (NA) in the dorsal and ventral hippocampus and the frontal cortex, along with histological changes in kaolin-induced hydrocephalic rats. Kaolin-induced hydrocephalic rats were divided into three groups (non-impaired, impaired and severely impaired) according to the degree of impairment in a radial maze. Thirty percent of the hydrocephalic rats could not solve a radial maze (severely impaired group), while the remaining hydrocephalic rats could (non-impaired rats in the standard task). Forty percent of the non-impaired rats in the standard task failed to solve the delayed-response task (impaired group), whereas the remaining rats were able to solve it (non-impaired group). A positive correlation was observed between the impairment of spatial memory and ventricular dilatation. The ACh content in the dorsal and ventral hippocampus, and the NA content in the ventral hippocampus were decreased in the severely impaired group. Moreover, the NA content in the ventral hippocampus was decreased in the impaired group. These results suggest that the impairment of spatial memory in kaolin-induced hydrocephalic rats is associated with dysfunction of the hippocampal cholinergic and noradrenergic systems.
Egawa
Takashi
T
Department of Physiology and Pharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-Ku, Fukuoka, Japan.
Mishima
Kenichi
K
Egashira
Nobuaki
N
Fukuzawa
Misa
M
Abe
Kohji
K
Yae
Tetsuji
T
Iwasaki
Katsunori
K
Fujiwara
Michihiro
M
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D006849:Hydrocephalus / Q000139:chemically induced / Q000473:pathology / Q000523:psychology*; D007427:Intracranial Pressure / Q000502:physiology; D007616:Kaolin; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008569:Memory Disorders / Q000209:etiology / Q000523:psychology*; D008570:Memory, Short-Term / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013028:Space Perception / Q000502:physiology*
D007616:Kaolin; D000109:Acetylcholine; D009638:Norepinephrine