NOVEL DIET CONSUMPTION AND BODY-WEIGHT GAIN ARE REDUCED IN RATS CHRONICALLY INFUSED WITH LITHIUM-CHLORIDE - MEDIATION BY THE CHEMOSENSITIVE AREA POSTREMA

The effects of chronic lithium chloride infusions on consumption of, and subsequent preferences for, a novel diet were examined in rats with ablations of the area postrema (AP) and sham-lesioned control rats. Osmotic minipumps (Alza), filled with a saturated aqueous solution of LiCl (63 g/100 ml), were implanted in the peritoneal cavity of half of the lesioned rats (n = 9) and half of the control rats (n = 8). The remaining rats received empty pumps (n = 9 and n = 7 for lesioned and controls, respectively). The LiCl or sham drug phase was paired with free access to a highly palatable novel diet (AIN diet) during a 7-day conditioning period. Subsequent preferences for the novel diet relative to a familiar diet (ground Purina lab pellets) were determined using a two-food choice procedure. The only group to show a persistent and significant reduction in novel food consumption during the conditioning phase was the sham-lesioned group infused with LiCl (p< 0.0 1). This group also exhibited a marked aversion for the novel diet, indicative of a conditioned food aversion (CFA), during the preference tests. No significant differences in novel diet consumption or in novel diet preference were found between the two AP-lesioned groups. This study provides evidence that anorexia and CFAs to a novel diet, induced with chronic infusions of lithium, are abolished by destruction of the chemosensitive area postrema.