Title

Effects of chlorhexidine rinse on salt taste in human and hamster: Psychophysical, immunohistochemical and electrophysiological studies

Date of Completion

January 2006

Keywords

Biology, Neuroscience|Health Sciences, Medicine and Surgery|Biology, Physiology|Health Sciences, Immunology

Degree

Ph.D.

Abstract

One of the side effects of chlorhexidine use is alteration of taste perception in humans. The objectives of these experiments are to evaluate the effects of chlorhexidine on salt taste perception in humans, to study the effect of chlorhexidine on the structure of the lingual taste cells and to evaluate the effect of chlorhexidine on the chorda tympani nerve responses in hamsters. Eight salts with equal intensity were selected for study (NaBr, KBr, CaBr 2, MgBr2, Na2SO4, K2SO 4, CaCl2, and MgSO4), sucrose and water. Ten subjects participated in the taste confusion matrix (TCM) experiment. Whole mouth "sip and spit" methodology was adopted. Data analyzed were percent correct, and the information theory measures, T2 & T10. Results indicated, relative to water, three 1-minute rinses with 1.34 mM chlorhexidine disrupted the taste qualities of all the monovalent salts (P<0.0001) tested, sparing 3 of 4 the divalent salts. ^ The effect of a five-minute 1.34 mM chlorhexidine application on lingual epithelium taste cell morphology was studied with a series of immunohistochemistry experiments in 12 golden hamsters. Specific taste cell marker protein antibodies for type I, II, and III mammalian taste cells (ESPIN, NCAM, PLCβ2, and IP3RIII) were used to distinguish taste cells from other non-taste epithelial cells. Light microscope data indicated there was no structural changes in the taste cells and no difference in the amount of fluorescence emitted per unit area from treated (chlorhexidine) and untreated (water) tongue tissues (p>0.05). ^ Two electrophysiological integrated chorda tympani (CT) nerve recording experiments were conducted. The first experiment was conducted on 6 golden hamsters to evaluate the effect of rinse time with ascending concentrations of chlorhexidine (0.3, 1.0, 3.0 mM) on CT nerve activity. Data indicated that both rinse time and concentration affected the basal activity of the chorda tympani nerve (p< 0.03 and p< 0.002, respectively). The effects of 1.34 mM chlorhexidine (Peridex®) on CT nerve responses to stimuli used in the TCM were evaluated in a second experiment. Data indicated that there was a trend for chlorhexidine to reduce the chorda tympani nerve responses elicited by the TCM stimuli (p = 0.06). ^