Imatinib Mesylate Reduces Voiding Frequency in Female Mice With Acute Cyclophosphamide-Induced Cystitis

Abstract

Lamina propria interstitial cells that express the tyrosine kinase receptor, platelet-derived growth factor receptor alpha (PDGFRα) may play a role in urinary sensory signaling. Imatinib mesylate, also referred to as imatinib, is a tyrosine kinase inhibitor that can inhibit PDGFRα and has been widely used in urological research. We evaluated the functional effects of imatinib administration (via oral gavage or intravesical infusion) with two different experimental designs (prevention and treatment), in a cyclophosphamide (CYP)-induced cystitis (acute, intermediate, and chronic), male and female rodent model using conscious cystometry and somatic sensitivity testing. Imatinib significantly (0.0001 ≤ p ≤ 0.05) decreased voiding frequency and increased bladder capacity in acute CYP-induced cystitis, by the prevention (females) and treatment (females and males) designs. Imatinib was not effective in preventing or treating intermediate or chronic CYP-induced cystitis in either sex. Interestingly, in the prevention experiments, imatinib administration increased (0.0001 ≤ p ≤ 0.01) voiding frequency and decreased bladder capacity in control mice. However, in the treatment experiments, imatinib administration decreased (0.01 ≤ p ≤ 0.05) voiding frequency and increased bladder capacity in control mice. Bladder function improvements observed with imatinib treatment in acute CYP-induced cystitis mice remained and additionally improved with a second dose of imatinib 24 hours after CYP treatment. Imatinib administration did not affect pelvic somatic sensitivity in female mice with acute CYP-induced cystitis. Our studies suggest that (1) imatinib improves bladder function in mice with acute CYP-induced cystitis with a prevention and treatment design and (2) interstitial cells may be a useful target to improve bladder function in cystitis.

Keywords: conscious cystometry; imatinib mesylate; interstitial cells; interstitial cystitis; platelet-derived growth factor receptor (PDGFR); somatic sensitivity.

FIGURE 1

Imatinib mesylate pre-treatment via oral gavage significantly alters intermicturition interval (IMI) and infused volume (IV) in an acute (4 h) cyclophosphamide (CYP)-induced cystitis mouse model. (A) Acute CYP-induced cystitis (200 mg/kg, 4 h, i.p.) experimental schedule for imatinib mesylate pre-treatment via oral gavage (250 mg/kg, 5 days, 1X/day). (B,D) Imatinib mesylate pre-treatment significantly increased IMI and IV (p ≤ 0.001) in female mice with acute (4 h) CYP-induced cystitis. (C,E) Imatinib mesylate pre-treatment did not significantly affect bladder measures in male mice with acute CYP-induced cystitis. (B–E) Imatinib pre-treatment alone by gavage, without CYP, significantly (0.01 ≤ p ≤ 0.0001) decreased IMI and IV in both female and male mice, compared to vehicle treatment alone. n = 5–9. Values are mean ± SEM. *p ≤ 0.05; ^**p ≤ 0.01; ^***p ≤ 0.001; ^****p ≤ 0.0001 by two-way ANOVA with Bonferroni’s multiple comparisons test. CMG, cystometrogram.

FIGURE 2

Imatinib mesylate treatment via intravesical infusion significantly increases IMI and IV in an acute (4 h) CYP-induced cystitis mouse model. (A) Acute CYP-induced cystitis (200 mg/kg, 4 h, i.p.) experimental schedule for imatinib mesylate treatment via intravesical infusion (50 μM, 30 min, 0.5 mL). (B–E) Imatinib treatment via intravesical infusion significantly increases the IMI and IV in female (p ≤ 0.0001) and male (p ≤ 0.05) with acute (4 h) CYP-induced cystitis. Imatinib treatment via intravesical infusion significantly increases the IMI and IV in female (p ≤ 0.01) and male (p ≤ 0.05) control (no CYP) mice. Control (no CYP) and 4 h CYP treated mice were separate groups of mice, each tested before and after imatinib infusion. n = 6–10. Values are mean ± SEM. *p ≤ 0.05; ^**p ≤ 0.01; ^****p ≤ 0.0001 by two-way repeated measures ANOVA with Šídák’s multiple comparisons test. CMG, cystometrogram.

FIGURE 3

Representative bladder function cystometry recordings from female mice with acute CYP-induced cystitis, pre-treated with imatinib mesylate or vehicle via oral gavage. (A,B) Mice with 4 h CYP-induced cystitis (200 mg/kg, 4 h, i.p.) pre-treated with vehicle exhibited significantly decreased IMI (p ≤ 0.001) and IV (p ≤ 0.0001), compared to control mice. (C,D) Mice with 4 h CYP-induced cystitis pre-treated with imatinib (250 mg/kg, 5 days, 1X/day) exhibited significantly (p ≤ 0.001) increased IMI and IV, compared to mice with 4 h CYP-induced cystitis pre-treated with vehicle. Recordings are from separate cohorts of mice. n = 5–9. By two-way ANOVA with Bonferroni’s multiple comparisons test. CMG, cystometrogram; BP, bladder pressure.

FIGURE 4

Representative bladder function cystometry recordings from a female mouse with acute CYP-induced cystitis, before and after imatinib mesylate treatment via intravesical infusion. (A,B) Before imatinib treatment via intravesical infusion, mice with acute CYP-induced cystitis (200 mg/kg, 4 h, i.p.) exhibited decreased IMI and IV. (C,D) After imatinib treatment via intravesical infusion (50 μM, 30 min, 0.5 ml), mice with 4 h CYP-induced cystitis exhibited significantly (p ≤ 0.0001) increased IMI and IV. Recordings displayed are from the same mouse, before and after imatinib treatment. Mice with 4 h CYP-induced cystitis in these experiments acted as their own controls. n = 6–10. By two-way repeated measures ANOVA with Šídák’s multiple comparisons test. CMG, cystometrogram; BP, bladder pressure.

FIGURE 5

Imatinib mesylate pre-treatment via gavage does not significantly affect bladder function in mice with chronic (8 day) CYP-induced cystitis. (A) Chronic CYP-induced cystitis (75 mg/kg, every 72 h for 8 days) experimental schedule for imatinib mesylate pre-treatment via oral gavage (250 mg/kg, 1X/day). (B,C) Imatinib pre-treatment via gavage did not significantly affect IMI or IV in female mice with chronic CYP-induced cystitis. n = 7–9. Values are mean ± SEM by two-way ANOVA with Bonferroni’s multiple comparisons test. CMG, cystometrogram.

FIGURE 6

Imatinib mesylate treatment via intravesical infusion does not significantly affect bladder function in mice with chronic (8 day) CYP-induced cystitis. (A) Chronic CYP-induced cystitis (75 mg/kg, every 72 h for 8 days) experimental schedule for imatinib mesylate treatment via intravesical bladder infusion (50 μM, 30 min, 0.5 mL). (B,C) Imatinib treatment via intravesical bladder infusion did not significantly affect IMI or IV in chronic CYP-induced cystitis, female mice. n = 7–9. Values are mean ± SEM by Student’s paired t-test. CMG, cystometrogram.

FIGURE 7

Two intravesical infusions with imatinib mesylate significantly increases IMI and IV in female mice with acute (4 h) CYP-induced cystitis. (A) Acute CYP-induced cystitis (200 mg/kg, 4 h, i.p.) experimental schedule for two-dose imatinib mesylate treatment via intravesical bladder infusion (50 μM, 30 min, 0.5 mL). Acute cystitis is induced on the third day. Bladder function with cystometrogram (CMG) is recorded 4 h after the CYP injection, before and after an intravesical bladder infusion of imatinib mesylate, and again, 24 h after the CYP injection on day 4, before and after a second imatinib mesylate intravesical bladder infusion. (B,C) Imatinib mesylate treatment significantly (p ≤ 0.01) increased the IMI and IV in female mice with acute CYP-induced cystitis at 4 and 24 h (p ≤ 0.001) following CYP. n = 4. Values are mean ± SEM. *p ≤ 0.05; ^**p ≤ 0.01; ^***p ≤ 0.001; by two-way repeated measures ANOVA with Bonferroni’s multiple comparisons test. CMG, cystometrogram.