[Modified ornithine decarboxylase medium and identification of Klebsiella and Enterobacter].
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Carboxy-Lyases↗
Biomedical subjects
N Okado
Publications and source records attributed to N Okado.
Maternal stress induces synaptic loss and developmental disabilities of offspring.
Mild prenatal stress affects the serotonergic system in the hippocampus of rat offspring. Pregnant rats were daily exposed to mild stress treatments (consisting of crowding and saline injection) during days 15 to 21 of pregnancy. Their offspring were assessed by a series of biochemical, histological and behavioral tests. On 35 days after birth, 5-hydroxytryptamine (5-HT) level was decreased by 17% (P < 0.05), whereas 5-hydroxyindolacetic acid (5-HIAA) level was increased by 18% (P < 0.05) in the offspring of prenatally stressed rats. The metabolic rate (5-HIAA/5-HT) was increased by 49% (P < 0.01). Synaptic density in the hippocampus of prenatally stressed offspring was also decreased by 32% (P < 0.0001) on postnatal day 35. There was no significant group difference in the spatial learning acquisition test of the Morris water maze; however, in the reversal task, prenatally stressed 5-week old rats spent more time than control animals searching for the platform of the pool. Escape latency in the cued test showed no significant difference. Together with data in our previous studies, that have shown 5-HT to facilitate synapse formation and maintenance in the central nervous system, synaptic loss is suggested to occur in relation to changes of 5-HT system in the hippocampus of prenatally stressed offspring. This may be associated with reported changes in behavior and learning ability in prenatally stressed offspring.
Animals↗
Regional differences of serotonin-mediated synaptic plasticity in the chicken spinal cord with development and aging.
Previous studies in our laboratory [3,17] have demonstrated that serotonin (5-HT) appears to have a trophic-like effect in enhancing synapse formation and maintenance in both the developing and the adult central nervous system. In the present study, we focused on age-related changes in the density of the axosomatic and axodendritic synapses and the number of 5-HT-positive fibers in the chicken spinal cord, with special reference to differences between the ventral (laminae VII and IX) and the dorsal (lamina I) horn. At 1 week posthatching (P1W), a transient overproduction of synapses and 5-HT-immunoreactive fibers occurred in lamina IX; all parameters had returned to their initial levels by 1 month post-hatching (P1M). The density of synapses further decreased by about 40% between P6M and P2Y (2 years posthatching). Although the magnitude of the transient increase in lamina VII was less than that in lamina IX, the changing pattern of the synapses and the 5-HT-positive fibers was similar in both regions. In the ventral horn, thin 5-HT-positive fibers were most prominent at P1W and then decreased with development; thin 5-HT-positive fibers were still found at P6M but had almost disappeared by P2Y. By contrast, at P2Y the density of the synapses and the 5-HT-positive fibers in the dorsal horn was even higher than that of younger animals. Reduction of 5-HT levels in P2Y-old chickens by p-chlorophenylalanine (pCPA) administration decreased the synaptic density in lamina I but not in lamina IX. The results of this study demonstrate that 5-HT-mediated synaptic plasticity is markedly different in the ventral and dorsal horns of the aged chicken. In the ventral horn, synaptic plasticity reached a maximum at about P1W, remained stable in the young-adult period, and then finally disappeared in the aged chicken. Conversely, the results suggest that in the dorsal horn, 5-HT fibers continue to mediate the trophic influence on synaptic plasticity even in the old chicken.
Aging↗