Acute restriction impairs memory in the elevated T-maze (ETM) and modifies serotonergic activity in the dorsolateral striatum.
Serotonin (5-HT) is involved in behaviors such as sleep, eating, memory, in mental disorders like anxiety and depression and plays an important role in the modulation of stress. On the other hand, exposure to stress influence learning as well as declarative and non-declarative memory. These effects are dependent on the type of stressor, their magnitude, and the type of memory. The striatum has been associated with non-declarative procedural memory, while the information about stress effects on procedural memory and their relation with striatal serotonin is scarce. The objective of this study was to evaluate the effects of stress on the modifications of the striatal serotonergic system. In Experiment 1, the effects of either 60 min of restraint (R) or exposure to the elevated T-maze (ETM) was assessed. Exposure to ETM decreased 5-HT concentration and to R increased 5-HT activity ([metabolite]/[neurotransmitter]). In Experiment 2, we evaluated the effects of restraint on ETM trained immediately, 24 or 48 h after restraint. No effects were detected in acquisition or escape latencies, while retention latencies were lower in all groups compared with the non-restrained group, although significant effects were detected immediately and 24h after restraint. The memory impairment seems to be associated with changes in striatal serotonergic system, given that 5-HT concentration increased, while serotonergic activity decreased. The differences in the activity of 5-HT detected in each experiment could be explained by the effects of different stressors on the serotonergic neurons ability to synthesize the neurotransmitter. Thus, we suggest that exposure to stress impairs procedural memory and that striatal serotonin modulates this effect.
Cruz-Morales
Sara Eugenia
SE
Psychopharmacology, FES-Iztacala, UNAM, P.O. Box 314, Tlalnepantla, México, Zip Code 54090, Mexico. saracruz@servidor.unam.mx
García-Saldívar
Norma Laura
NL
González-López
María Reyes
MR
Castillo-Roberto
Georgina
G
Monroy
Juana
J
Domínguez
Roberto
R
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000378:metabolism / Q000503:physiopathology; D001522:Behavior, Animal / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004924:Escape Reaction / Q000502:physiology; D005106:Exploratory Behavior / Q000502:physiology; D006897:Hydroxyindoleacetic Acid / Q000032:analysis / Q000378:metabolism; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D017072:Neostriatum / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical / Q000379:methods; D012153:Retention, Psychology / Q000502:physiology; D012701:Serotonin / Q000032:analysis / Q000378:metabolism*; D013315:Stress, Psychological / Q000503:physiopathology
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid