Effects of gustatory deafferentation on Polycose and sucrose appetite in the rat

Recent studies have revealed that rats are strongly attracted to the taste of starch-derived polysaccharides, and suggest that the taste receptors involved differ from those that respond to sucrose. The present study examined the possibility that different gustatory nerves mediate the rat's taste and appetite for polysaccharides and sucrose. This was accomplished by measuring the effects of selective gustatory nerve transection on the intake of Polycose and sucrose solutions in nondeprived female rats. Bilateral transection of the chorda tympani nerve produced comparable reductions in Polycose and sucrose intake, but bilateral transection of the glossopharyngeal nerve selectively reduced the intake of Polycose. Bilateral transection of the greater superficial petrosal nerve, and to a lesser degree, the pharyngeal branch of the vagus nerve, increased sucrose intake without affecting Polycose intake. These results indicate that while no single gustatory nerve mediates sucrose or polysaccharide taste, there is some specialization of function within the peripheral gustatory system. Combined bilateral transections of all four gustatory nerves produced the greatest reduction in solution intake, and reduced Polycose and sucrose consumption to the same degree. The suppressive effect was only partial, however, which indicates that relatively few intact taste receptors are required to maintain the rat's appetite for sugar and polysaccharide solutions.