Three-week-old male rats were given 2.7mEq Li
2CO
3/kg/day orally for 1 or 3 weeks, and the level of IP
3 in the brain was estimated. Although the level of IP
3 was not affected by the administration of Li
2CO
3, IP
3 was further fractionated to I-1, 3, 4-P
3 and I-1, 4, 5-P
3 by HPLC. The relative percentages of I-1, 3, 4-P
3 and I-1, 4, 5-P
3 were 95.8 and 4.2 in controls and 69.6 and 30.4 in brains of rats treated with lithium. Since I-1, 4, 5-P
3 is known to be a messenger inside the cells to regulate cell-to-cell communication compared with I-1, 3, 4-P
3, this increase in the relative level of I-1, 4, 5-P
3 in the brain might be relevant for the treatment of manic-depressive disorders.
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