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Spatial memory impairment under a radial-arm maze task in microcephalic rats induced by prenatal methylazoxymethanol acetate (MAM) treatment
s159
AGE RELATED REVERSAL
CHANGES
LEARNING
IN BRAIN MONOAMINE
TASK DETERMINED
KOII HORI, TUNICHI TANAKA,
CONTENT!3 OF RATS DURING
A
BY IN WV0 MICRODIALYSIS
AND MASAHIKO
NOMURA.
Detmrtment
of Physiolow
Saitama Medical School, 38 Morovama-machi, Iruma-rmn, Saitama, 350-04. TaDan Aging effects on the brain monoamine using young
(3 months
discriminate
light on/off
primary
learning
contents during a reversal learning task were investigated
old) and aged (24 months
old) rats as the subjects.
states under the operant type learning procedure.
phase showed no significant
differences
learning phase, however, aged rats performed significantly revealed
that the contents
increased during learning increases.
between
Task performances
two age-groups.
to
in the
In the reversal
worse than young rats. In oioo microdialysis
of DA, DOPAC, and 5-HIAA in the amygdala of young rats significantly task as compared to baseline levels. In contrast, aged rats showed no such
These results suggest that the plasticity of behavior is diminished
changes in dopaminergic
Rats were trained
with aging, and age-related
and serotonergic system may be involved in this process.
SPATIAL MEMORY IMPAIRMENT UNDER A RADIAL-ARM MAZE TASK IN MICROCEPHALIC RATS INDUCED BY PRENATAL METHYLAZOXYMETHANOL ACETATE (MAM) TREATMENT. KOZO SUGIOKA AND TAKASHI YAMADORI, First Department of Anatomy, Kobe University School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650 Japan. The ability of spatial recognition in microcephalic rats under a radial-arm maze task was examined. These rats were obtained from Jcl: Wistar rats treated with a single dose of 30 mg/kg methylazoxymethanol acetate (MAM) on the day 13 of pregnancy (plug = day 0). At stage 1, the Mm-treated rats as well as control rats which had been injected the same amount of physiological saline were tested on a radial-arm maze to run to the end of each arm for a reward for 20 sessions At stage 2, a delayed radial-arm maze task was administered to these 2 groups to examine the retention of working memory. In the task 5, 10, 20 and 30 min of delay intervals were introduced immediately after the first 4 choices and then the rats were tested to obtain the remaining 4 rewards. The MAM-treated rats showed significantly more errors than the control rats in the first 8 choices (stage 1). The retention test revealed that the MAM-treated rats showed an impairment of working memory when the retention interval was 10 min or more (stage 2). These behavioral results were discussed in relation to large reduction in size of the cerebral cortex and morphological abnormality (the presence of ectopic CA 1 and 2 pyramidal neurons) of the hippocampus.
ESTABLISHMENT OF TWO-CELL INTRACELLULAR LABELING TECHNIQUE FOR THE ANALYSIS OF ASSOCIATION FIBERS OF THE CA3 HIPPOCAMPAL PYRAMIDAL NEURONS NOBUAKI TAMAMAKI AND YOSHIAKI NOJYO, Department of Anatomy, Fukui Medical School, Matsuoka. Fukui _S!O-11 Japan is alternations in synaptic efficacy, such as A mechanism underlying memory long-term potentiation (LTP) Empirically, a depolarization large enough to form LTP is caused by giving high-frequency activation or depolarizing current with electrodes. However, we hypothesize that the large depolarization in hippocampal CA1 pyramidal neurons is achieved by convergence of neuronal activity originating from the CA3 pyramidal neurons. In order to estimate the convergence of information input to the CA1 pyramidal neurons through the association and projection fibers of the CA3 pyramidal neurons. we investigate these synaptic connections using a two-cell intracellular labeling technique. First. we injected 10% neuroblotin solution under pressure into a single CA38 pyramidal neuron A few hours later. we injected 5% HRP solution into other CA3a pyramida I neurons located at various distances from the neurobiotin-filled neuron. After sectioning with a cryostat, the serial sections were reacted with Co-DAB to stain the HRP-injected neurons black. Then the sections ware processed for ABC reaction to detect neurobiotin. This technique allows us to count possible synaptic contacts on the entire dendritio tree of a CA3 pyramidal neuron made by the association fibers of another CA3 pyramidal neuron.
AGE RELATED REVERSAL
CHANGES
LEARNING
IN BRAIN MONOAMINE
TASK DETERMINED
KOII HORI, TUNICHI TANAKA,
CONTENT!3 OF RATS DURING
A
BY IN WV0 MICRODIALYSIS
AND MASAHIKO
NOMURA.
Detmrtment
of Physiolow
Saitama Medical School, 38 Morovama-machi, Iruma-rmn, Saitama, 350-04. TaDan Aging effects on the brain monoamine using young
(3 months
discriminate
light on/off
primary
learning
contents during a reversal learning task were investigated
old) and aged (24 months
old) rats as the subjects.
states under the operant type learning procedure.
phase showed no significant
differences
learning phase, however, aged rats performed significantly revealed
that the contents
increased during learning increases.
between
Task performances
two age-groups.
to
in the
In the reversal
worse than young rats. In oioo microdialysis
of DA, DOPAC, and 5-HIAA in the amygdala of young rats significantly task as compared to baseline levels. In contrast, aged rats showed no such
These results suggest that the plasticity of behavior is diminished
changes in dopaminergic
Rats were trained
with aging, and age-related
and serotonergic system may be involved in this process.
SPATIAL MEMORY IMPAIRMENT UNDER A RADIAL-ARM MAZE TASK IN MICROCEPHALIC RATS INDUCED BY PRENATAL METHYLAZOXYMETHANOL ACETATE (MAM) TREATMENT. KOZO SUGIOKA AND TAKASHI YAMADORI, First Department of Anatomy, Kobe University School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650 Japan. The ability of spatial recognition in microcephalic rats under a radial-arm maze task was examined. These rats were obtained from Jcl: Wistar rats treated with a single dose of 30 mg/kg methylazoxymethanol acetate (MAM) on the day 13 of pregnancy (plug = day 0). At stage 1, the Mm-treated rats as well as control rats which had been injected the same amount of physiological saline were tested on a radial-arm maze to run to the end of each arm for a reward for 20 sessions At stage 2, a delayed radial-arm maze task was administered to these 2 groups to examine the retention of working memory. In the task 5, 10, 20 and 30 min of delay intervals were introduced immediately after the first 4 choices and then the rats were tested to obtain the remaining 4 rewards. The MAM-treated rats showed significantly more errors than the control rats in the first 8 choices (stage 1). The retention test revealed that the MAM-treated rats showed an impairment of working memory when the retention interval was 10 min or more (stage 2). These behavioral results were discussed in relation to large reduction in size of the cerebral cortex and morphological abnormality (the presence of ectopic CA 1 and 2 pyramidal neurons) of the hippocampus.
ESTABLISHMENT OF TWO-CELL INTRACELLULAR LABELING TECHNIQUE FOR THE ANALYSIS OF ASSOCIATION FIBERS OF THE CA3 HIPPOCAMPAL PYRAMIDAL NEURONS NOBUAKI TAMAMAKI AND YOSHIAKI NOJYO, Department of Anatomy, Fukui Medical School, Matsuoka. Fukui _S!O-11 Japan is alternations in synaptic efficacy, such as A mechanism underlying memory long-term potentiation (LTP) Empirically, a depolarization large enough to form LTP is caused by giving high-frequency activation or depolarizing current with electrodes. However, we hypothesize that the large depolarization in hippocampal CA1 pyramidal neurons is achieved by convergence of neuronal activity originating from the CA3 pyramidal neurons. In order to estimate the convergence of information input to the CA1 pyramidal neurons through the association and projection fibers of the CA3 pyramidal neurons. we investigate these synaptic connections using a two-cell intracellular labeling technique. First. we injected 10% neuroblotin solution under pressure into a single CA38 pyramidal neuron A few hours later. we injected 5% HRP solution into other CA3a pyramida I neurons located at various distances from the neurobiotin-filled neuron. After sectioning with a cryostat, the serial sections were reacted with Co-DAB to stain the HRP-injected neurons black. Then the sections ware processed for ABC reaction to detect neurobiotin. This technique allows us to count possible synaptic contacts on the entire dendritio tree of a CA3 pyramidal neuron made by the association fibers of another CA3 pyramidal neuron.