Tyrosine Ameliorates a Cold-Induced Delayed Matching-to-Sample Performance Decrement in Rats
NAVAL MEDICAL RESEARCH INST BETHESDA MD
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Exposure to cold stress has been shown to impair short-term, or working, memory which may be related to a reduction in brain catecholamines. Administration of the catecholamine precursor tyrosine may alleviate a cold- stress-induced memory impairment by preventing a deficit in brain catecholamine levels. To test this hypothesis, eight rats performed a delayed matching-to- sample DMTS task at an ambient temperature of either 2 deg C cold or 22 deg C, following, intraperitoneal administration of saline or tyrosine 50, 100 or 200 mgkg. Rats administered saline prior to 22 deg C exposure demonstrated a characteristic delay gradient in which accuracy decreased as the delay interval between sample and comparison stimuli increased from 1 to 16 s. Consistent with previous research, and relative to 22 deg C exposure sessions, matching accuracy during 2 deg C exposure sessions was reduced, which is attributed to the effect of cold on short-term, or working, memory.
- Stress Physiology