RUI: Taste of Monosodium Glutamate and Sweet

Regis University, Denver CO

Investigators

Abstract

Monosodium glutamate (MSG) is found in many high protein foods such as meat and fish and it is often added to food to enhance the taste of food. However, we do not understand how our taste receptors detect the taste of MSG. One way we can study these processes is to compare the behavioral responses of rats to MSG with their responses to other taste stimuli. For example, rats normally prefer the taste of MSG but if they experience gastric distress after ingesting MSG, these rats will avoid MSG and anything that tastes like MSG. This is called conditioned taste aversion (CTA). The proposed research is designed to test this hypothesis. We first need to determine whether the taste of MSG with amiloride mimics taste qualities of other sweet substances. There are at least two mechanisms that taste receptors use to detect sweet substances, one for natural sugars such as sucrose and another for artificial sweeteners such as saccharin. The first experiments will use CTA and behavioral discrimination procedures to determine if rats perceive the taste of MSG with amiloride as similar to sweet substances other than sucrose (natural sugars and artificial sweeteners). These experiments will help determine whether the taste of glutamate is similar to either natural sugars, artificial sweeteners, or to both. If the taste of MSG with amiloride is similar to sweet stimuli then these taste stimuli may be coded by cells in the same areas of the nervous system. To test this hypothesis, another experiment will use a cell marker method to identify cells in the brain stem (solitary nucleus) activated by MSG and those sweet stimuli that taste most like glutamate in the first experiments. The degree to which the location of cells activated by these stimuli overlap with each other may indicate the degree to which the neurons involved in coding of these taste stimuli interact within the gustatory system of the brain stem The information learned from these experiments will help us understand why MSG increases the palatability of some foods and may be used to help people, such as the elderly or diabetics, who need dietary regulation.