Time course changes of estrogen receptor alpha expression in the adult rat hippocampus after kainic acid-induced status epilepticus.

Although estrogens possess neuroprotective and epileptogenic properties, the expression pattern of the estrogen receptor (ER) following status epilepticus (SE) remains unclear. We therefore examined the expression pattern of ER alpha in the adult rat hippocampus after SE. SE was induced in rats by kainic acid (KA; 12 mg/kg, i.p.). ER alpha expression was assessed by immunostaining and Western blotting at various times (24 h, and 7, 14, and 21 days) after SE onset. Immunohistochemistry disclosed ER alpha expression in the CA1 and CA3 pyramidal cells of control rats, whereas, after SE, ER alpha-immunoreactive neurons decreased in number due to neuronal death in the CA1 from days 7 to 21. On the other hand, ER alpha-immunoreactive cells with astrocytic morphology were observed in the CA1 beginning on day 7 after SE. This immunoreactivity increased in proportion to the hypertrophy of astrocytes up to day 21. Western blotting revealed a significant decrease in ER alpha expression on day 7 after SE in comparison with control level. However, ER alpha expression on days 14 and 21 were similar when comparing KA-treated and control rats. These results indicate that reactive astrocytes are important sites of estrogen action in the hippocampal CA1 after SE.

Disruption of the CAR1 gene encoding arginase enhances freeze tolerance of the commercial baker's yeast Saccharomyces cerevisiae.

The effect of intracellular charged amino acids on freeze tolerance in dough was determined by constructing homozygous diploid arginase-deficient mutants of commercial baker's yeast. An arginase mutant accumulated higher levels of arginine and/or glutamate and showed increased leavening ability during the frozen-dough baking process, suggesting that disruption of the CAR1 gene enhances freeze tolerance.