Correlations among central serotonergic parameters and age-related emotional and cognitive changes assessed through the elevated T-maze and the Morris water maze.
Emotion and spatial cognitive aspects were assessed in adult and middle-aged rats using the elevated T-maze (ETM) and the Morris water maze (MWM) tasks. Both adult and middle-aged rats were able to acquire inhibitory avoidance behaviour, though the middle-aged subjects showed larger latencies along the trials, including the baseline, which was significantly longer than that showed by adult rats. Further, compared to adult rats, middle-aged rats had longer escape latency. In spite of the worse performance in the second session of the spatial cognitive task, the middle-aged rats were able to learn the task and remember the information along the whole probe trial test. Both thalamic serotonin (5-HT) concentration and amygdala serotonergic activity (5-HIAA/5-HT) are significantly correlated, respectively, to escape latency and behavioural extinction in the MWM only for middle-aged rats. A significant correlation between the 5-HIAA/5-HT ratio in the amygdala and behavioural extinction for middle-aged, but not for adult, rats was observed. This result suggests that serotonergic activity in the amygdala may regulate behavioural flexibility in aged animals. In addition, a significant negative correlation was found between hippocampal 5-HIAA/5-HT ratio and the path length at the second training session of the MWM task, although only for adult subjects. This was the only session where a significant difference between the performance of middle-aged and adult rats has occurred. Although the involvement of the hippocampus in learning and memory is well established, the present work shows, for the first time, a correlation between a serotonergic hippocampal parameter and performance of a spatial task, which is lost with ageing.
Oliveira
Luciana
L
Laboratório de Neurociências Comportamental e Molecular, LaNeC, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil.
Graeff
Frederico G
FG
Pereira
Silvia R C
SR
Oliveira-Silva
Ieda F
IF
Franco
Glaura C
GC
Ribeiro
Angela Maria
AM
D000339:Affect; D000367:Age Factors; D000818:Animals; D001522:Behavior, Animal; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology; D004195:Disease Models, Animal; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D051381:Rats; D012701:Serotonin / Q000502:physiology*
D012701:Serotonin