Comparison of acute and chronic lithium treatment on 3H-norepinephrine uptake by rat brain slices

The effects of lithium chloride, given IP in high (2.5-15 mEq/kg) and low (1.25 mEq/kg) doses twice daily, upon 3H-norepinephrine uptake and retention were examined with slices from four regions of the rat brain, namely brain stem, hypothalamus, parietal cortex, and caudate nucleus. Control uptake was significantly higher in slices from the caudate nucleus and lower in brain stem slices than in slices from hypothalamus or parietal cortex. With the higher doses, uptake increased significantly in all regions after 2 days of treatment and returned to normal by 7 days. With the lowest dose, uptake was increased after 7 days but normal at 14 days. Only in caudate slices was there a second elevation of 3H-norepinephrine uptake after 21 days of treatment, which returned to normal by 42 days. No other effects were observed during 70 days of treatment with lithium. The correlation between changes in 3H-norepinephrine uptake and plasma lithium levels was studied.