Calcium hunger in the parathyroidectomized rat is specific

Calcium ingestion consequent on a challenge to calcium homeostasis such as parathyroidectomy or calcium deficient diet often appears to be nonspecific: rats rendered calcium deficient by a calcium-deficient diet increase ingestion of many tastants besides calcium, including MgCl2 and in particular, NaCl. Rats rendered calcium deficient by parathyroidectomy (PTX) have also been reported to increase ingestion of magnesium. Thus, magnesium, a chemically related molecule, and NaCl, a preferred mineral, pose challenges to the notion of a specific calcium hunger in calcium-deficient rats. Here, we reexamine the specificity of calcium preference of rats rendered calcium hungry by PTX by allowing them to choose between CaCl2 and MgCl2, and between CaCl2 and NaCl. We find that PTX rats clearly prefer calcium to either tastant. A review of the literature on tastant selection by calcium-hungry rats suggests that, given the choice between calcium and other tastants, they prefer calcium. Our findings lend credence to the notion of a calcium specific appetite in calcium-deficient rats.