Chronic hypodipsia to intraperitoneal and subcutaneous hypertonic saline after vagotomy

Recent studies suggest that the decreased drinking response to hypertonic saline produced by bilateral subdiaphragmatic vagotomy (VGX) is a function of the route of saline administration and the length of postoperative recovery. We determined the effects of VGX on drinking during the two hours after intraperitoneal and subcutaneous injections of 0.25, 0.5 and 1.0% body weight doses of 1 M NaCl 30 weeks after surgery. Regardless of the route of injection of saline, VGX rats took longer to initiate drinking and drank less water after the two highest doses than controls. Although VGX rats drank less than controls after both routes of injection, the decrease in water intake was greater after intraperitoneal administration. We conclude that, since both deficits were obtained regardless of the route of saline injection 30 weeks after surgery, route of administration and length of postoperative recovery are not important factors for demonstrating impairments in the drinking elicited by hypertonic saline after total abdominal vagotomy under our experimental conditions.