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Prevention by intrinsic and extrinsic bFGF of ischemic neuronal loss and learning disability in gerbils
s149 1314
THE INHIBITION OF NEURONAL ACTIVITY, THE SYNAPTIC DEATH AND THE NEURONAL DEATH INDUCED BY GLUTAMATE IN CULTURED CORTICAL NEURONAL NETWORKS. KUNIHIKO UMEZAWA1,', KAZUO KOBAYASHIl, AYUMU NOZAWAI, KAZUYO MTJRAMOTO', MASAHIRO KAWAHARAl, AND YOICHIRO KURODAl, 'Deot. of Molecular and Cellular Neurobioloav, Tokvo Metrowolitan Institute for Neruoscience, Musashidai, Fuchu-shi, Tokvo, Jawan, 'Dewt. of Neurosuraerv, Tohoku Univ. Sch. of Med., Sendai. Jawan
In previous studies we reported that the periodic synchronized bursting indicating the neuronal activity with intracellular calcium transients (Robinson, H. P. C., et al, J. Neurophysio1.70:1606-1616, 1993) increased during the development and was correlated to the number of synapses in cultured cortical neuronal networks (Muramoto, K ., et. al, Neurosci. Lett., 163: 163-165, 1993). We observe that the exposure of glutamate to the neuronal networks inhibit the synchronized bursting in the dose-dependent manner. We discuss relationship between the inhibition of neuronal activity and the synaptic/neuronal death induced by glutamate.
1315
PREVENTION BY INTRINSIC AND EXTRINSIC bFGF OF ISCHEMIC NEURONAL LOSS AND LEARNING DISABILITY IN GERBILS. MASAHIRO SAKANAKA AND SEIJI MATSUDA. Deoartment of Anatomy, Ehime Universitv School of Medicine, Shiaenobu, Ehime 791-02 Japan
Platelet factor 4 (PF4) has been shown to inhibit binding of basic fibroblast growth factor (bFGF) to the cell surface receptor and to counteract the biological activities of bFGF in certain peripheral tissues. To investigate the function of endogenous bFGF and/or bFGF receptor possibly activated in the ischemic gerbil brain, we infused PF4 continuously into the left lateral ventricle with an osmotic minipump. When PF4 infusion was started within 3 days after a 3-min ischemic insult, it caused a significant dose-dependent decline in learning ablllty and a significant decrease in the number of viable hippocampal CA1 neurons demonstrated by the results of the step-down passive avoidance task and by subsequent histological examinations. bFGF coinfused with heparin, but not bFGF alone, rescued a significant number of ischemic neurons which were destined to degenerate without the infusion of heparinized bFGF, and it prevented ischemiainduced learning disability. bFGF infusion prior to PF4 treatment abolished almost completely the neurotoxic effect of PF4 on the ischemic hippocampal CA1 region. These findings suggest that endogeneous bFGF acts as a neurotrophic factor in ischemic brains.
1316
APOPTOSIS OF THE CA1 PYRAMIDAL NEURONS IN GERBIL HIPPOCAMPUS FOLLOWING TRANSIENT ISCHEMIA. TOHRU NITATORJ’, JjQ&JRU SATQ’,YASUKO
UCHIYAfvlA1, m~enter.
KARASAWA*, J-lIFtOAKI AFtAKf*, ElK13,
lpept. of Cell BjgL. and Neuroanat.., Taisho Pharmaceu$cal CO.. LTD.. Yosw.
Univ. Sch. of Med.. Howvo.113.
.
OhmI-
.
AND Y&!%!Q *QQD~.of Pharmacol..
I %st. DeDt.
&ga3
The CA1 pyramidal neurons in the hippocampus are known to be selectively vulnerable to brief ischemia of the global cerebrum, resulting in delayed neuronal death several days after ischemic insult. It remains, however, unknown whether this delayed neuronal death is necrosis or apoptosis. We have previously demonstrated
that nuclei of the CA1 pyramidal neurons were positively stained
by in situ nick end labeling of dUTP (TUNEL) 3 and 4 days after ischemic insult, but not in the prior stages.
In the present study, we
further examined the dying processes of the neurons by light and electron microscopy, and Southern blot. By electron microscopy, dense chromatin masses in nuclei of the neurons and apoptotic bodies appeared in the pyramidal layer 4 days after ischemic insult. Southern blot analysis revealed that laddering of fragmented DNA occurred only in CA1 hippocampal tissues obtained 4 days after ischemic damage.
Moreover, by confocal laser scanning microscopy, TUNEL-positive
nuclei in the CA1
pyramidal layer were phagocytosed by microglial cells. The results suggest that delayed death of the CA1 pyramidal neurons following transient ischemia is not necrotic but apoptotic.
THE INHIBITION OF NEURONAL ACTIVITY, THE SYNAPTIC DEATH AND THE NEURONAL DEATH INDUCED BY GLUTAMATE IN CULTURED CORTICAL NEURONAL NETWORKS. KUNIHIKO UMEZAWA1,', KAZUO KOBAYASHIl, AYUMU NOZAWAI, KAZUYO MTJRAMOTO', MASAHIRO KAWAHARAl, AND YOICHIRO KURODAl, 'Deot. of Molecular and Cellular Neurobioloav, Tokvo Metrowolitan Institute for Neruoscience, Musashidai, Fuchu-shi, Tokvo, Jawan, 'Dewt. of Neurosuraerv, Tohoku Univ. Sch. of Med., Sendai. Jawan
In previous studies we reported that the periodic synchronized bursting indicating the neuronal activity with intracellular calcium transients (Robinson, H. P. C., et al, J. Neurophysio1.70:1606-1616, 1993) increased during the development and was correlated to the number of synapses in cultured cortical neuronal networks (Muramoto, K ., et. al, Neurosci. Lett., 163: 163-165, 1993). We observe that the exposure of glutamate to the neuronal networks inhibit the synchronized bursting in the dose-dependent manner. We discuss relationship between the inhibition of neuronal activity and the synaptic/neuronal death induced by glutamate.
1315
PREVENTION BY INTRINSIC AND EXTRINSIC bFGF OF ISCHEMIC NEURONAL LOSS AND LEARNING DISABILITY IN GERBILS. MASAHIRO SAKANAKA AND SEIJI MATSUDA. Deoartment of Anatomy, Ehime Universitv School of Medicine, Shiaenobu, Ehime 791-02 Japan
Platelet factor 4 (PF4) has been shown to inhibit binding of basic fibroblast growth factor (bFGF) to the cell surface receptor and to counteract the biological activities of bFGF in certain peripheral tissues. To investigate the function of endogenous bFGF and/or bFGF receptor possibly activated in the ischemic gerbil brain, we infused PF4 continuously into the left lateral ventricle with an osmotic minipump. When PF4 infusion was started within 3 days after a 3-min ischemic insult, it caused a significant dose-dependent decline in learning ablllty and a significant decrease in the number of viable hippocampal CA1 neurons demonstrated by the results of the step-down passive avoidance task and by subsequent histological examinations. bFGF coinfused with heparin, but not bFGF alone, rescued a significant number of ischemic neurons which were destined to degenerate without the infusion of heparinized bFGF, and it prevented ischemiainduced learning disability. bFGF infusion prior to PF4 treatment abolished almost completely the neurotoxic effect of PF4 on the ischemic hippocampal CA1 region. These findings suggest that endogeneous bFGF acts as a neurotrophic factor in ischemic brains.
1316
APOPTOSIS OF THE CA1 PYRAMIDAL NEURONS IN GERBIL HIPPOCAMPUS FOLLOWING TRANSIENT ISCHEMIA. TOHRU NITATORJ’, JjQ&JRU SATQ’,YASUKO
UCHIYAfvlA1, m~enter.
KARASAWA*, J-lIFtOAKI AFtAKf*, ElK13,
lpept. of Cell BjgL. and Neuroanat.., Taisho Pharmaceu$cal CO.. LTD.. Yosw.
Univ. Sch. of Med.. Howvo.113.
.
OhmI-
.
AND Y&!%!Q *QQD~.of Pharmacol..
I %st. DeDt.
&ga3
The CA1 pyramidal neurons in the hippocampus are known to be selectively vulnerable to brief ischemia of the global cerebrum, resulting in delayed neuronal death several days after ischemic insult. It remains, however, unknown whether this delayed neuronal death is necrosis or apoptosis. We have previously demonstrated
that nuclei of the CA1 pyramidal neurons were positively stained
by in situ nick end labeling of dUTP (TUNEL) 3 and 4 days after ischemic insult, but not in the prior stages.
In the present study, we
further examined the dying processes of the neurons by light and electron microscopy, and Southern blot. By electron microscopy, dense chromatin masses in nuclei of the neurons and apoptotic bodies appeared in the pyramidal layer 4 days after ischemic insult. Southern blot analysis revealed that laddering of fragmented DNA occurred only in CA1 hippocampal tissues obtained 4 days after ischemic damage.
Moreover, by confocal laser scanning microscopy, TUNEL-positive
nuclei in the CA1
pyramidal layer were phagocytosed by microglial cells. The results suggest that delayed death of the CA1 pyramidal neurons following transient ischemia is not necrotic but apoptotic.