Ki67-positive cells.

<p>Ki67-positive cells.</p

Representative bright field images of H and E stained fungiform and circumvallate taste buds at Days 4, 7, 10 and 16 post-injection of saline, CYP or AMF/CYP-injected mice.

<p>(a) Images of fungiform taste buds. Morphologically intact taste buds with organized mass of taste cells (indicated by black arrow) are abundant in saline-injected (control) mice. There was a disruption in the organization of taste buds, seen as an absence of organized mass of taste cells (indicated by green arrow) in CYP-injected mice on day 4 which does not recover until day 16 post-injection. AMF/CYP-injected mice do not show this disruption except on day 7. (b) Trench of a circumvallate papilla with taste buds. The red-boxed area shows the region which is magnified to observe detailed morphology. (c) Images of circumvallate taste buds. There was no morphological change in the circumvallate taste buds of saline and AMF mice across days. However there were open-spaces (red arrow) inside the taste buds on days 7 and 10 in CYP-injected mice. AMF/CYP–injected mice showed such “open spaces” (red arrow) only on day 7. Scale bar = 25 µm.</p

Representative images of PLCβ2-positive cells (red) in fungiform and circumvallate taste buds on days 4, 7, 10 and 16 post-injection in saline-, CYP- or AMF/CYP-injected mice.

<p>Sytox green was used as a nuclear marker. There was a reduction in the number of PLCβ2-positive cells in fungiform and circumvallate taste buds on day 4 in CYP-injected mice but not in AMF/CYP-injected mice. The bar graphs illustrate the mean (± SEM) number of PLCβ2-positive cells in fungiform (upper graph) and circumvallate (lower graph) taste buds across days in each drug group. (<b>a</b>) In fungiform taste buds, there was a reduction in the number of PLCβ2-positive cells on day 4, 7 and 10 in CYP-injected mice and on day 7 in AMF/CYP-injected mice. Scale bar = 25 µm. (<b>b</b>) In circumvallate taste buds, there was a reduction in the number of PLCβ2-positive cells on day 7 and 10 in CYP-injected mice and on day 7 in AMF/CYP-injected mice. Scale bar = 50 µm. (*** <i>P</i><0.001;** <i>P</i><0.01;* <i>P</i><0.05).</p

PLCβ2-positive cells.

<p>PLCβ2-positive cells.</p

Mean (± SEM) number of BrdU-positive cells in the basal layer of fungiform papillae and taste buds, one wall of each circumvallate trench, and a sample area of the lingual epithelium in Saline, CYP and AMF/CYP mice on days 4, 7, 10 and 16 post–injection.

<p>(<b>a</b>) BrdU-positive cells in the basal layer of fungiform taste papillae and taste buds of each drug condition. (<b>b</b>) BrdU-positive cells in the basal layer of one wall of a circumvallate trench for each drug condition. (<b>c</b>) BrdU-positive cells in lingual epithelium of each drug condition (*** <i>P</i><0.001;** <i>P</i><0.01;* <i>P</i><0.05).</p

Pre-Treatment with Amifostine Protects against Cyclophosphamide-Induced Disruption of Taste in Mice

<div><p>Cyclophosphamide (CYP), a commonly prescribed chemotherapy drug, has multiple adverse side effects including alteration of taste. The effects on taste are a cause of concern for patients as changes in taste are often associated with loss of appetite, malnutrition, poor recovery and reduced quality of life. Amifostine is a cytoprotective agent that was previously shown to be effective in preventing chemotherapy-induced mucositis and nephrotoxicity. Here we determined its ability to protect against chemotherapy-induced damage to taste buds using a mouse model of CYP injury. We conducted detection threshold tests to measure changes in sucrose taste sensitivity and found that administration of amifostine 30 mins prior to CYP injection protected against CYP-induced loss in taste sensitivity. Morphological studies showed that pre-treatment with amifostine prevented CYP-induced reduction in the number of fungiform taste papillae and increased the number of taste buds. Immunohistochemical assays for markers of the cell cycle showed that amifostine administration prevented CYP-induced inhibition of cell proliferation and also protected against loss of mature taste cells after CYP exposure. Our results indicate that treatment of cancer patients with amifostine prior to chemotherapy may improve their sensitivity for taste stimuli and protect the taste system from the detrimental effects of chemotherapy.</p> </div

AMF protects against the CYP-induced decreases in taste sensitivity and the number of fungiform papillae with and without pore, and improves overall morphological index of fungiform taste buds.

<p>(A) Sucrose detection thresholds, before and after saline, CYP, AMF or AMF/CYP injection. The graph shows the mean (± SEM) threshold concentration of sucrose (Y-axis, log scale) across days (X-axis) post-injection. Days −1, −2 indicate thresholds before the injection. CYP-injected mice showed significant elevations of sucrose detection thresholds on days 2–5 and 9–15 after injection, while AMF/CYP-injected mice showed significant elevation in sucrose detection threshold on days 9–11 post-injection. (B) Mean (± SEM) number of all fungiform papillae across days post-injection. CYP injection significantly decreased the total number of fungiform taste papillae on post-injection days 4, 7 and 10 compared with saline control mice. AMF/CYP-injected mice had significantly higher number of papillae compared to CYP-injected mice on days 4 and 7. (C) Mean (± SEM) number of fungiform papillae with a taste pore across days post-injection. There was also a significant drop in the number of fungiform taste papillae with pores on days 4, 7 and 10 compared with saline controls. AMF/CYP groups had significantly higher number of papillae with pores on days 4, 7 and 10 compared to CYP groups. To the right of the graph are examples of a fungiform papilla without (upper image) and with a pore (lower image). The red arrow identified the opening of a pore. (D) Morphological index of fungiform papillae across days in saline-, CYP- or AMF/CYP-injected mice. The morphological index is expressed as p/P, where p = proper taste buds and P = Total number of taste buds. There was a significant decrease in the morphological index for CYP-injected mice on days 4, 7 and 10 compared to saline controls. AMF/CYP mice revealed a protective effect of AMF on days 4 and 7 (*** <i>P</i><0.001;** <i>P</i><0.01;* <i>P</i><0.05).</p

Representative images of Ki67-positive cells (red) in fungiform taste papillae with taste buds and in taste buds in circumvallate trenches on days 4, 7, 10 and 16 post-injection of saline-, CYP- or AMF/CYP-injected mice.

<p>Sytox green was used as a nuclear marker. There was a reduction in the number of Ki67-positive cells in the basal layer of fungiform taste papillae and the basal layer of circumvallate taste buds on day 4 in CYP-injected mice but not in AMF/CYP-injected mice. The bar graphs illustrate the mean (± SEM) number of Ki67-positive cells in fungiform papillae (upper graph) and the basal layer of one wall of each circumvallate trench (lower graph) across days in each drug group. (<b>a</b>) Ki67-positive cells in the basal layer of fungiform taste papilla and taste bud. Scale bar = 25 µm. (<b>b</b>) Ki67-positive cells in the basal layer of one wall of each circumvallate trench. Scale bar = 50 µm (*** <i>P</i><0.001;** <i>P</i><0.01;* <i>P</i><0.05).</p