Polyamines have various roles in cortical development. We examined the ontogenic changes in ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, in cerebral cortices of normal and hydrocephalic rats. Both biochemical and immunohistochemical examinations revealed increased ODC protein and enzyme activity during the perinatal period. Apical dendrites of developing neuroblasts migrating from the superficial layer of cortical plate showed intense ODC immunoreactivity. Once they had settled at their final destination, ODC immunoreactivity weakened. Both ODC immunoreactivity and enzyme activity reached very low levels after completion of layer formation of cortex. The enzyme activity of ODC in hydrocephalic cortices exceeded that in normal cortex during the perinatal periods. ODC was rather overexpressed, but no characteristic distribution was observed in the hydrocephalic cortex. These findings indicate the participation of polyamines in the cortical development, especially in the layer formation. The overexpression of ODC in hydrocephalus appears to promote development despite increased hydrostatic pressure.

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PubMedDate not supplied

Ornithine decarboxylase in developing brain of hydrocephalic rats. Effects of shunt operation.

We examined the changes in ornithine decarboxylase (ODC) immunoreactivity in the hydrocephalic cerebral cortex of HTX rats after decompression by shunt operation. The ODC immunoreactivity reached a very low level after the completion of cortical layer formation, and only faint staining was found on postnatal day (Pd) 11. The ODC immunoreactivity re-appeared after the shunt operation when the operation was done in the early days of life: the ODC immunoreactivity was first found on day 2 after shunting and persisted until day 8 after shunting. However, this was not apparent when the operation was not performed until Pd 14. The re-expression of ODC in hydrocephalic brain after shunting appears to cause resumption of the developmental process by relieving neurons from increased hydrostatic pressure. The dependence of ODC re-expression on the timing of the operation indicates that there may be a period of neocortical decompression that is critical for effective compensatory development, so that when delayed, decompression fails to re-activate the ODC-dependent development.

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PubMedDate not supplied

Effect of long-term exercise under restricted-feeding on intestinal content of cholecystokinin and on the pancreas in aging rats.

The effects of exercise (5000 m/day running from 100 to 600 days of age) on the cholecystokinin (CCK) content in the proximal intestine, and the enzyme and insulin contents of the pancreas were examined in food-restricted rats. Food restriction decreased the body weight and the wet weights of the pancreas and proximal intestine but not the wet weight of the stomach. Food restriction also decreased the chymotrypsin content of the pancreas but not its amylase content. The contents of enzymes in the pancreas were not affected by exercise. The insulin content of the pancreas was lower in lean rats produced by food restriction and/or exercise than in controls. Exercise increased the wet weight of the proximal intestine and the CCK content of the intestine. The increase in the CCK content may be due to compensational change in the efficiency of digestion of luminal nutrients induced by exercise.

Journal Article↗

PubMedDate not supplied

Female-soiled bedding induced fos immunoreactivity in the ventral part of the premammillary nucleus (PMv) of the male mouse.

Previous studies have indicated that the ventral part of the premammillary nucleus (PMv) of rodents is involved in the regulation of aggressive and male mating behavior, although the precise physiological function of the PMv is still unclear. To analyze the physiological role of the PMv in male mating behavior, the effects of exposure to bedding soiled by female mice on Fos immunoreactivity (Fos-ir), an early marker of neuronal activation, were studied in the PMv and some sex-related nuclei. We observed that exposure to female-soiled bedding induced Fos-ir expression in the PMv of the male mouse. Although Fos-ir positive cells were found in the posterodorsal part of the medial amygdaloid nucleus and in the posteromedial cortical amygdaloid nucleus, which are terminals of the neuronal projections from the main and accessory olfactory bulbs, the numbers of Fos-ir cells in those nuclei were not affected by exposure to female-soiled bedding. Moreover, Fos-ir was not detected in the ventromedial hypothalamic nucleus. It is well established that soiled bedding is useful as a source of chemosensory substances, which include "pheromones." Thus, our findings, in agreement with previous behavioral and anatomical data, suggest that the PMv plays a role in initiating male copulative behavior that is induced by a female mice pheromone(s).

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PubMedDate not supplied

An autoradiographic study of the renewal of mouse bronchiolar epithelium following bromobenzene exposure.

This study discusses mice bronchiolar epithelium following bromobenzene (BrBZ) exposure. Our study shows 3 cell types following BrBZ exposure: Clara cells, ciliated cells, and newly discovered BrBZ-resistant nonciliated cells. Through electron microscopic autoradiography, we were able to show the proliferative ability of BrBZ-resistant nonciliated cells. This finding suggests that BrBZ-resistant nonciliated cells may function as progenitor cells. In addition to discovering this new cell type, our results also demonstrate and confirm the proliferative ability of modified Clara cells.

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PubMedDate not supplied

Elevated blood concentrations of cyclosporine and kidney failure after bezafibrate in renal graft recipient.

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Adult↗