Xanthine Oxidase Inhibitor, Febuxostat Is Effective against 5-Fluorouracil-Induced Parotid Salivary Gland Injury in Rats Via Inhibition of Oxidative Stress, Inflammation and Targeting TRPC1/CHOP Signalling Pathway

Abstract

The current research aimed to examine the ameliorative role of febuxostat (FEB), a highly potent xanthine oxidase inhibitor, against 5-fluorouracil (5-FU)-induced parotid salivary gland damage in rats, as FEB is a pleiotropic drug that has multiple pharmacological effects. A total of 32 Wistar adult male rats were randomly arranged into four groups. Group 1: the control group; given only the vehicle for 14 days, then given a saline i.p. injection from the 10th to the 14th day. Group 2: the FEB group; rats received FEB (10 mg/kg) once daily po for 14 days before receiving a saline i.p. injection from the 10th to the 14th day. Group 3: the 5-FU group; from the 10th to the 14th day, rats received an intraperitoneal injection of 5-FU (35 mg/kg/day). Group 4: the FEB/5-FU group; rats were pre-treated with FEB po for 14 days before receiving 5-FU i.p injections for five consecutive days from the 10th to the 14th day. Parotid gland damage was detected histologically and biochemically by the evaluation of oxidative stress markers (malondialdehyde (MDA) and nitric oxide levels (NOx)), oxidant defences (reduced glutathione (GSH) and superoxide dismutase (SOD)), inflammatory markers (tumour necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β)), and transient receptor potential canonical1 (TRCP1) and C/EBP homologous protein (CHOP). FEB pre-treatment reduced MDA, TNF-, and IL-1 while increasing SOD, GSH, and NOx. FEB also significantly increased TRPC1 and decreased CHOP in parotid gland tissue. In conclusion, FEB pre-treatment reduced 5-FU-induced parotid salivary gland damage not only through its powerful anti-inflammatory and antioxidant effects, but also through its effect on the TRPC1/CHOP signalling pathway.

Keywords: CHOP; TRPC1; febuxostat; fluorouracil; parotid damage.

Figure 1

Impact of FEB on TRPC1 (A) and CHOP (B) in 5-FU-induced parotid salivary gland toxicity. Values are expressed as the mean ± S.D. Results were considered significantly different when p < 0.05. ^a Significant difference compared to the control group, ^b significant difference compared to the FEB group, and ^c significant difference compared to the 5-FU group. (TRPC1: transient receptor potential canonical1; CHOP: C/EBP homologous protein; 5-FU: 5-Fluorouracil, and FEB: febuxostat) (8 rats/group).

Figure 2

Photomicrographs of the parotid salivary gland of the studied groups. (a,b) The control and FEB groups, respectively, showed intact parotid parenchyma; serous acini (S) and striated ducts (D). Note the myoepithelial cells (↑). (c) The 5-FU group showed parenchymal changes; coalesced serous acini (S), pyknotic nuclei (↑↑), cellular infiltration (I), interrupted lining of striated ducts (arrowhead), retained secretion (*), and dilated congested blood vessels (↑). (d) The FEB + 5-FU group showed normal parotid structure; serous acini (S), striated ducts (D), and myoepithelial cells (arrowhead) except for mildly congested blood vessels (↑). (H&E ×400; 8 rats/group).

Figure 3

Photomicrographs of semi-thin sections of the parotid salivary gland. (a,b) The control and FEB groups, respectively, showed intact parenchyma with packed serous acini (S), thin septa (↑), and blood vessel (arrowhead). Inset: striated duct (D) lined by low columnar cells (green arrow) and surrounded with myoepithelial cells (↑↑). (c) The 5-FU group showed serous acini (S) separated by wide spaces (*) and congested blood vessel (B.V). Notice the vacuolation (V). (d) The FEB + 5-FU group showed packed acini with few vacuolations (arrowhead). (Toluidine blue ×400; 8 rats/group).

Figure 4

Photomicrographs of the α-SMA immunoreaction at the periphery of the acini (↑). (a,b) The control and FEB groups, respectively, showed a faint immunoreaction. (c) The 5-FU group showed a marked immunoreaction. (d) The FEB + 5-FU group showed a moderate immunoreaction. (α-SMA immunostaining, ×400; 8 rats/group).

Figure 5

Scores of the histological findings. Values were expressed as the mean ± S.D. (A) shows the cellular infiltration score. (B) shows the vacuolation score. (C) shows the congestion score. Results were considered significantly different when p < 0.05. ^a Significant difference relative to the control, ^b significant difference relative to the FEB group, and ^c significant difference relative to the 5-FU group. (5-FU: 5-fluorouracil and FEB: febuxostat; 8 rats/group).