Effects of pretreatment with single-dose or intermittent oxygen on Cisplatin-induced nephrotoxicity in rats

Abstract

Background: Renal injury is the main side effect of cisplatin (CP), an anticancer drug. It has been shown that pretreatment with single-dose oxygen (0.5 to six hours) could reduce CP-induced renal toxicity in rats.

Objectives: The present study aimed to compare the effects of pretreatment with single-dose and intermittent O2 on CP-induced nephrotoxicity.

Materials and methods: Adult male rats were allocated to seven groups (eight rats in each group). The rats were kept in normal air or hyperoxic environment (O2, 80%) for either a single six-hour period or intermittent six hours per day for seven days and then were subjected to intraperitoneal injection of saline or CP (5 mg/kg) at 48 hours, 72 hours, or seven days after exposure to O2. Three days after CP (or Saline) injection, renal function tests, renal tissue injury scores, and cleaved Caspase-3 and Bax/Bcl-2 genes expression (as markers of renal cell apoptosis) were assessed.

Results: Treatment with the 6-hour single-dose O2 reduced renal injury significantly when CP was administrated 48 hours after O2 pretreatment. Pretreatment with intermittent seven days of six hours per day had no protective effects and even relatively worsened renal injury when CP was injected 48 hours or 72 hours after the last session of O2 pretreatment. The beneficial effects of pretreatment with O2 on renal structure and function were seen if CP was administrates seven days after pretreatment with intermittent O2.

Conclusions: The pattern of pretreatment with O2 could change this potential and highly protective strategy against CP-induced nephropathy to an ineffective or even mildly deteriorating one. Therefore, O2 administration before CP injection to patients with cancer, for therapeutic purposes or as a preconditioning approach, should be performed and investigated with caution until exact effects of different protocols has been determined in human.

Keywords: Cisplatin; Hyperoxia; Oxygen; Preconditioning; Toxicity.

Figure 1.. Renal Function Tests

For explanation about different groups, see text (***, P ≤ 0.005 in comparison with “Air + CP” group; **, 0.005 < P ≤ 0.01 in comparison with “Air + CP” group; *, 0.01 < P ≤ 0.05 in comparison with “Air + CP” group; a, 0.05 < P ≤ 0.08 in comparison with “Air + CP” group; and #, insignificantly different from “Air + Saline” group).

Figure 2.. Western Blot Analysis of Cleaved Caspase-3/β-actin and Bax/Bcl2/β-actin Gene Expression

For explanation about different groups see text (***, P ≤ 0.005 in comparison with “Air + CP” group; **, 0.005 < P ≤ 0.01 in comparison with “Air + CP” group; *, 0.01 < P ≤ 0.05 in comparison with “Air + CP” group; and #, insignificantly different from “Air + Saline” group).

Figure 3.. Light Microscopy of Kidney Specimens (H & E, ×100) From Groups 2 Through 7, Respectively

The normal appearances of renal tissue sections from group 1 are not shown. For detailed explanation about different groups see text. A, Group 2 (O₂ + Saline), normal. B, Group 3 (6hO2 48hLCP), almost normal. C, Group 4 (7dayO2 48hLCP), sever acute tubular necrosis (ATN). D, Group 5 (7dayO2 72hLCP), sever ATN. E, Group 6 (7dayO2 7dayLCP), mild ATN. F, Group 7 (Air + CP) almost severe ATN.

Figure 4.. Light Microscopy of a Kidney Specimen (H&E, ×400) Showing Karyomegaly (Arrows) Three Days After Cisplatin Administration (This Was From Group 5).

The karyomegaly percentage was determined as an injury score in different groups (see text and Figure 5).

Figure 5.. Histological Assessments

For explanation about different groups, see text (***, P ≤ 0.005 in comparison with “Air + CP” group; **, 0.005 < P ≤ 0.01 in comparison with “Air + CP” group; *, 0.01 < P ≤ 0.05 in comparison with “Air + CP” group; and #, insignificantly different from “Air + Saline” group).