Role of kinin B1 and B2 receptors in memory consolidation during the aging process of mice.
Under physiological conditions, elderly people present memory deficit associated with neuronal loss. This pattern is also associated with Alzheimer's disease but, in this case, in a dramatically intensified level. Kinin receptors have been involved in neurodegeneration and increase of amyloid-beta concentration, associated with Alzheimer's disease (AD). Considering these findings, this work evaluated the role of kinin receptors in memory consolidation during the aging process. Male C57Bl/6 (wt), knock-out B1 (koB1) or B2 (koB2) mice (3, 6, 12 and 18-month-old - mo; n=10 per group) were submitted to an acquisition session, reinforcement to learning (24h later: test 1) and final test (7days later: test 2), in an active avoidance apparatus, to evaluate memory. Conditioned avoidance responses (CAR, % of 50 trials) were registered. In acquisition sessions, similar CAR were obtained among age matched animals from all strains. However, a significant decrease in CAR was observed throughout the aging process (3mo: 8.8+/-2.3%; 6mo: 4.1+/-0.6%; 12mo: 2.2+/-0.6%, 18mo: 3.6+/-0.6%, P<0.01), indicating a reduction in the learning process. In test 1, as expected, memory retention increased significantly (P<0.05) in all 3- and 6-month-old animals as well as in 12-month-old-wt and 12-month-old-koB1 (P<0.01), compared to the training session. However, 12-month-old-koB2 and all 18-month-old animals did not show an increase in memory retention. In test 2, 3- and 6-month-old wt and koB1 mice of all ages showed a significant improvement in memory (P<0.05) compared to test 1. However, 12-month-old wt and koB2 mice of all ages showed no difference in memory retention. We suggest that, during the aging process, the B1 receptor could be involved in neurodegeneration and memory loss. Nevertheless, the B2 receptor is apparently acting as a neuroprotective factor.
Lemos
Mayra Tolentino Resk
MT
Department of Physiological Sciences, Faculdade de Ciências Médicas da Santa Casa de São Paulo. Rua Dr. Cesario Motta Junior, 61, São Paulo, SP, CEP 01221-020, Brazil.
Amaral
Fabio Agostini
FA
Dong
Karis Ester
KE
Bittencourt
Maria Fernanda Queiroz Prado
MF
Caetano
Ariadiny Lima
AL
Pesquero
João Bosco
JB
Viel
Tania Araujo
TA
Buck
Hudson Sousa
HS
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009043:Motor Activity / Q000502:physiology; D043783:Receptor, Bradykinin B1 / Q000502:physiology*; D043782:Receptor, Bradykinin B2 / Q000502:physiology*
D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2