Effects of elevated calcium on learned helplessness and brain serotonin metabolism in rats

The effects of elevated calcium on learned helplessness in rats was tested by maintaining animals on either distilled water or water containing 2.5% calcium. Animals that were maintained on drinking water containing high calcium showed elevated levels of brain and serum calcium. Rats that were maintained on high calcium drinking water showed significantly longer escape latencies than their non-calcium counterparts after they were pretreated with inescapable electric shocks. Lower levels of 5-hydroxyindoleacetic acid (5HIAA) were found in the forebrain and brainstem of animals maintained on high calcium drinking water. There was no significant correlation between blood or brain calcium or 5HIAA levels and latency of escape. We conclude that elevated levels of calcium enhance learned helplessness and decrease brain serotonin turnover. The relationship between depressive states and calcium homeostasis is worthy of further investigation.