Effects of caffeine on learning and memory in rats tested in the Morris water maze

We studied some of the characteristics of the improving effect of the non-specific adenosine receptor antagonist, caffeine, using an animal model of learning and memory. Groups of 12 adult male Wistar rats receiving caffeine (0.3-30 mg/kg, ip, in 0.1 ml/100 g body weight) administered 30 min before training, immediately after training, or 30 min before the test session were tested in the spatial version of the Morris water maze task. Post-training administration of caffeine improved memory retention at the doses of 0.3-10 mg/kg (the rats swam up to 600 cm less to find the platform in the test session, P<=0.05) but not at the dose of 30 mg/kg. Pre-test caffeine administration also caused a small increase in memory retrieval (the escape path of the rats was up to 500 cm shorter, P<=0.05). In contrast, pre-training caffeine administration did not alter the performance of the animals either in the training or in the test session. These data provide evidence that caffeine improves memory retention but not memory acquisition, explaining some discrepancies among reports in the literature.

Memory; Learning; Caffeine; Methylxanthines; Adenosine receptor antagonist; Morris water maze

Authorship

M.E.M. Angelucci

Universidade Federal do Paraná, Departamento de Farmacologia , Laboratório de Fisiologia e Farmacologia do Sistema Nervoso Central, Curitiba, Paraná, BrazilUniversidade Federal do ParanáBrazilCuritiba, Paraná, BrazilUniversidade Federal do Paraná, Departamento de Farmacologia , Laboratório de Fisiologia e Farmacologia do Sistema Nervoso Central, Curitiba, Paraná, Brazil

Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba , Piracicaba, São Paulo, BrazilUniversidade Estadual de CampinasBrazilPiracicaba, São Paulo, BrazilUniversidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba , Piracicaba, São Paulo, Brazil

C. Cesário

R.H. Hiroi

P.L. Rosalen

C. Da Cunha

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Figures

Figures (4)

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Figure 1.
Effect of the administration of caffeine 30 min before the training session on the learning of the Morris water maze task. The results are reported as mean ± SEM latency (A) or distance (B) the animals traveled from the starting point to the submersed platform. The test trials were performed 48 h after the training trials. The X-axis represents the starting position for each trial. Two-way ANOVA showed a significant decrease in the scores as a function of the number of trials (P£0.05) but no significant effect of treatment either on the training or on the retention (test session) scores.

Thumbnail

Figure 2.
Effect of the administration of caffeine 30 min before the training session on swimming speed during the Morris water maze training trials. The results are reported as mean ± SEM. Two-way ANOVA showed a significant decrease in the scores as a function of the number of trials (P£0.05) but no significant effect of treatment either on the training or on the retention (test session) scores. The same analysis also showed a significant (P£0.05) interaction between the treatment and the repeated measure (trials).

Thumbnail

Figure 3.
Effect of the administration of caffeine immediately after the training session on the learning of the Morris water maze task. The results are reported as mean latency (A) or distance (B) the animals traveled from the starting point to the submersed platform. The test trials were performed 48 h after the training trials. The X-axis represents the starting position for each trial. *P£0.05 and **P£0.01 compared to control (Duncan test after two-way ANOVA related to test scores).

Thumbnail

Figure 4.
Effect of the administration of caffeine 30 min before the test session on the learning of the Morris water maze task. The results are reported as mean ± SEM latency (A) or distance (B) the animals traveled from the starting point to the submersed platform. The test trials were performed 48 h after the training trials. The X-axis represents the starting position for each trial. Two-way ANOVA of the test data showed a significant interaction between the caffeine treatment and the repeated measure in relation to the distance scores (P£0.05) but not in relation to latency scores. No significant effect of treatment on individual retention scores was observed.

Figure 1. Effect of the administration of caffeine 30 min before the training session on the learning of the Morris water maze task. The results are reported as mean ± SEM latency (A) or distance (B) the animals traveled from the starting point to the submersed platform. The test trials were performed 48 h after the training trials. The X-axis represents the starting position for each trial. Two-way ANOVA showed a significant decrease in the scores as a function of the number of trials (P£0.05) but no significant effect of treatment either on the training or on the retention (test session) scores.

Figure 2. Effect of the administration of caffeine 30 min before the training session on swimming speed during the Morris water maze training trials. The results are reported as mean ± SEM. Two-way ANOVA showed a significant decrease in the scores as a function of the number of trials (P£0.05) but no significant effect of treatment either on the training or on the retention (test session) scores. The same analysis also showed a significant (P£0.05) interaction between the treatment and the repeated measure (trials).

Figure 3. Effect of the administration of caffeine immediately after the training session on the learning of the Morris water maze task. The results are reported as mean latency (A) or distance (B) the animals traveled from the starting point to the submersed platform. The test trials were performed 48 h after the training trials. The X-axis represents the starting position for each trial. *P£0.05 and **P£0.01 compared to control (Duncan test after two-way ANOVA related to test scores).

Figure 4. Effect of the administration of caffeine 30 min before the test session on the learning of the Morris water maze task. The results are reported as mean ± SEM latency (A) or distance (B) the animals traveled from the starting point to the submersed platform. The test trials were performed 48 h after the training trials. The X-axis represents the starting position for each trial. Two-way ANOVA of the test data showed a significant interaction between the caffeine treatment and the repeated measure in relation to the distance scores (P£0.05) but not in relation to latency scores. No significant effect of treatment on individual retention scores was observed.

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Effects of caffeine on learning and memory in rats tested in the Morris water maze

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