Changes in drinking behavior caused by superior cervical ganglionectomy and pinealectomy in rats

The effect of superior cervical ganglionectomy (SCGx) or pinealectomy (Px) on drinking behavior was examined in rats subjected to a restricted photoperiod (i.e. 4 h of light per day). Both in male and female rats SCGx depressed water intake significantly from 1 to 3 days after surgery. After osmolar (i.p. 5% NaCl) or non-osmolar stimuli (s.c. isoproterenol) SCGx female rats exhibited a depressed response in water and NaCl intake, an effect not observed in male rats. Castration of male or female rats did not change their drinking behavior response to thirst stimuli. Px did not mimic SCGx in its effects on drinking behavior; moreover in sham-Px rats the water intake fell significantly after craniotomy. Following the injection of isoproterenol or i.p. hypertonic saline, the drinking behavior was the same in Px or sham-Px animals. To assess whether the effects of SCGx needed the presence of the pineal gland, Px or sham-Px rats were subjected to SCGx 9 days later. In both groups SCGx depressed water intake; however the inhibition that followed ganglia removal in Px rats was greater than that observed in animals with a pineal gland. Water and NaCl intake following isoproterenol or i.p. hypertonic saline were similar in both experimental groups. These results suggest that SCGx affects drinking behavior in part by pathways other than pineal denervation.