Calcium deprivation alters gustatory-evoked activity in the rat nucleus ofthe solitary tract

Calcium-deprived rats develop a compensatory appetite for substances that c ontain calcium. To investigate the role of gustatory factors in calcium app etite, we recorded the extracellular activity of single neurons in the nucl eus of the solitary tract of calcium-deprived and replete rats. The activit y evoked by a broad array of taste stimuli was examined in 51 neurons from replete rats and 47 neurons from calcium-deprived rats. There were no diffe rences between the groups in the responses of all neurons combined. However , neurons with sugar-oriented response profiles gave significantly larger r esponses to 3, 10, and 100 mM CaCl2 in the calcium-deprived group than did corresponding cells in the replete group. This difference in taste-evoked r esponding may underlie an increase in the palatability of CaCl2 and, in tur n, contribute to the expression of calcium appetite.