INGESTIVE PATTERNS OF LIVER-DENERVATED RATS PRESENTED WITH SEVERAL DIETS

The liver by way of afferent nerves is suggested to be a controller of food intake. In experiment 1, male rats were given a 15% fructose solution during the first 4 h of the dark phase, while chow was available the rest of the time, for 10 days, before total liver denervation (TLD) or sham operation. Postsurgery ingestion patterns (15-min measurements for 4 h) of fructose were similar in the two groups. However, chow intake in the TLD group was slightly attenuated the first 2 days after surgery. In experiment 2, rats were given chow in cups and vegetable oil in bottles for 8 days before TLD or sham operation. After surgery, hourly ingestion of chow and oil did not differ between the groups; however, there was a trend for the TLD group to take more oil in the dark phase on the first-day diet exposure. In experiment 3, rats were fed a high-protein diet for 21 days before TLD or sham operation. With the use of a computer-operated system, postsurgery meal size, meal duration, and frequency patterns were found to be comparable between the groups. In experiment 4, rats were given a diet of sweetened condensed milk mixed with water (3:1 vol/vol) and vitamins for 14 days before hepatic vagal branch transection (HVBX) or sham operation. After surgery the first-day milk intake of both groups was similar up to 3.5 h and then depressed at 4 and 24 h in the HVBX rats, but was again comparable over the next 13 days; body weights were similar throughout the study. The above data suggest liver innervation is not required for normal food intake regulation during the first few hours of diet exposure after denervation. Thereafter, on some of the tested diets there were some transient differences in consumption. Whether these changes were caused by a loss of afferent or efferent (or both) fibers is uncertain and may suggest subtle influences of liver innervation on the control of feeding.