Search

This study was performed to examine the differences in expression of heme oxygenase protein with age using immunocytochemistry. We compared the contents of HO-1 and HO-2 between young and aged rats using immunocytochemical methods. Stronger HO-1 expression was detected in the internal layer of the median eminence (ME) of aged than of young rats. Moreover, the cells expressing HO-1 were larger in the aged than the young animals. Electron microscopy indicated these cells with HO-1-like immunoreactivity (HO-1-LI) to be astrocytes. These findings suggested that the expression of HO-1 increased in the ME with age. The significance of this increased expression of HO-1 with age will be discussed briefly.

We investigated the effect of intravenous taurine infusion on the electroretinogram (ERG) of taurine-deficient rats produced by treatment with guanidinoethyl sulfonate (GES), a taurine transport inhibitor. Mother rats were fed a taurine-free diet and given drinking water containing 1% GES from 2 weeks of gestation to weaning. The same feeding conditions were applied to male offspring after weaning. Both ERG measurement and continuous infusion of taurine at a dose of 10, 30 or 100 mg/animal/day were performed for 3 weeks from 7 to 10 weeks of age. GES-treatment reduced a- and b-wave amplitudes to 50% of the control levels and also increased b-wave latencies. Intravenous infusion of taurine improved these ERG abnormalities in a dose-dependent manner. Taurine concentrations in plasma, eyes and brain were also decreased by treatment with GES, and dose-dependent recovery was observed after infusion with taurine, although the concentrations of other amino acids were not affected by GES-treatment and infusion of taurine. Observations of morphological changes revealed that the retinal damage in GES-treated animals was decreased by taurine infusion. These results indicate that the changes in ERG and retinal structure observed in taurine deficiency are improved by intravenous infusion of taurine.

Tyrosine hydroxylase (TH)-like immunoreactive neurons, fibers, and terminals in the hypothalamic arcuate nucleus and median eminence of young (8 weeks old) and aged (24 months old) rats were investigated at light and electron microscopic levels by means of the peroxidase anti-peroxidase (PAP) method. In the arcuate nucleus, TH-like immunoreactive neuronal perikarya of young animals contained well-developed cell organelles such as rough-surfaced endoplasmic reticulum (rER), mitochondria, Golgi apparatus, polysomes, as well as dense granules. Immunoreactive neuronal elements appeared as both presynaptic and postsynaptic elements. In aged rats, TH-like immunoreactive neuronal perikarya as well as non-immunoreactive ones were found to include many lysosomes or inclusions, and many neuronal elements with degradative changes were observed. In the external layer of the median eminence of young animals, many immunoreactive nerve endings were found around the pericapillary spaces of portal vessels and often terminated adjacent to the basement membranes of the pericapillary spaces. Immunoreactive fibers having close contact with non-immunoreactive fibers were also observed. In aged animals, degradative changes such as axons with swollen and watery appearance and myelin figures were observed in the neuronal elements, although many immunoreactive nerve endings were seen around the pericapillary spaces.