The effects of paradoxical sleep deprivation and valine on spatial learning and brain 5-HT metabolism.
We have previously reported that rapid eye movement sleep deprivation (REMSD), induced by the flower pot technique, causes a deficit in reference spatial memory and increases rates of serotonin (5-HT) metabolism in the brain. In this study we used increased concentrations of dietary valine to inhibit tryptophan (TRP) transport across the blood-brain barrier in an attempt to modify the REMSD-induced increase of 5-HT metabolism. Rats were fed either a control diet or the same diet supplemented to 2% by weight valine, and were allocated to one of three experimental groups: cage control (CC), stress tank control (TC), or REMSD. Reference and working spatial memory of all rats was tested in a Morris water maze on Days 2, 3, and 4. REMSD produced a significant decrement in reference memory on Days 2 and 4, independent of dietary condition. The valine diet had a detrimental effect on the reference memory of TC rats on Day 2 but not Day 4. Measurements made on Day 4 indicated that the valine diet decreased brain TRP only in the CC rats. In contrast, the valine diet did not prevent increases in brain TRP or 5-HT metabolism in REMSD rats, and increased hypothalamic and brain stem TRP concentrations and the hippocampal 5-HIAA/5-HT ratio in TC rats. These results indicate that dietary valine does not prevent REMSD-induced changes in spatial memory or serotonin metabolism, although it does reduce brain TRP in nonstressed rats.
Youngblood
B D
BD
Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
Smagin
G N
GN
Elkins
P D
PD
Ryan
D H
DH
Harris
R B
RB
D000818:Animals; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D001923:Brain Chemistry / Q000187:drug effects*; D004032:Diet; D004435:Eating / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D012892:Sleep Deprivation / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology*; D013315:Stress, Psychological / Q000378:metabolism / Q000523:psychology; D014364:Tryptophan / Q000378:metabolism; D014633:Valine / Q000494:pharmacology*
D012701:Serotonin; D014364:Tryptophan; D014633:Valine