Naloxone depresses osmoregulatory drinking in rats

The effect of an opiate antagonist, naloxone, on hypertonic NaCl-induced drinking was studied in rats in a within-subject design. Naloxone reduced drinking at all dosage levels used (0.3–10.0 mg/kg) when compared to a control condition. These results extend previous findings of naloxone mediated reduction in fluid intake in water deprived and osmotically challenged animals. Naloxone's effect on fluid intake seems to be independent of procedure employed, and thus quite general. Possible mechanisms were considered.