Morphological Changes in Taste Buds and Innervation After Acute Radiation
Creators: name: Zain, Rosnah Biniti Mohd
Publisher: name: My University
Year: 1982
Subjects: subject: Taste buds
subject: Hypogeusia
subject: Ageusia
subject: Radiation
subject: Dentistry
subject: FOS: Clinical medicine
subject: Health Sciences

description: In many clinical situations, decrease in taste sensation (hypogeusia), altered taste sensation (ageusia) have been noted to arise from a variety of causes. Among these are Sjögren's syndrome (Henkin et al., 1972), as well as diseases involving the middle ear such as choleastoma, acoustic neuroma, Bell's Palsy, and mastoid surgery (Bull, 1965). Taste impairment in Sjögren's syndrome has been attributed to xerostomia implying a close relationship between saliva and taste function. The rest of the above conditions are associated with damage or surgical transection of the chorda tympani nerves. These nerves carry sensory fibers from the taste receptors to the central nervous system. Morphologic and functional studies have been carried out on laboratory animals in order to understand the complexities of taste mechanisms. Therapeutic radiation may also cause changes in taste sensitivities. Complications after irradiation include mucositis, osteoradionecrosis, xerostomia, and dental caries (Regezi et al., 1976). The latter complications have been the subject of many animal investigations on post-irradiation effects (Shafer, 1952, 1953; English, 1956; Cherry and Glucksman, 1959; Leifer, 1971; and Rohrer, 1979). Only a few animal studies have reported the effects of irradiation on taste structure and function (Conger 1969, 1973; and Shaber, 1971). These studies have shown a loss of taste buds and a decrease in taste response following irradiation. A neural role similar to the effects of nerve degeneration on taste structure and function has been implicated (Conger, 1969, 1973). Since no morphological change had been observed by light microscopy, the neurological changes may be at an ultrastructural level. An underlying biochemical alteration within the nerve or at the neurosecretory junctions induced by radiation may also be a factor. In addition, Shaber (1971) suggested that there may be a depression of neurosecretory activity due to local toxin build-up and/or inhibition of the normal enzyme release which would explain the observed changes. The purpose of this study then will be to: 1. Determine whether there is loss in the number of taste buds on the fungiform papillae after acute irradiation. 2. Describe by light microscopy the morphology of taste buds following x-irradiation. 3. Determine whether any morphologic changes of the taste bud are associated with biochemical alterations within the nerve or neurosecretory junctions induced by radiation. The ultimate purpose of this research is to provide a basis for animal studies simulating the clinical situation in which patients suffering from oral cancer are being irradiated. The outcome of this study will, hopefully, provide a better explanation for the loss of the taste sensation experienced by these patients. Even though it has been clinically observed that taste sensation returns by 2-4 months post-irradiation of 3000 rads (Conger, 1973), this study may allow for a better appreciation of the neural mechanisms involved.