Developmental polychlorinated biphenyl (PCB) exposure alters voiding physiology in young adult male and female mice

Abstract

The impact of developmental exposure to environmental chemicals on lower urinary tract function is not well understood, despite the fact that these chemicals could contribute to etiologically complex lower urinary tract symptoms (LUTS). Polychlorinated biphenyls (PCBs) are environmental toxicants known to be detrimental to the central nervous system, but their impact on voiding function in mouse models is not known. Therefore, we test whether developmental exposure to PCBs is capable of altering voiding physiology in young adult mice. C57Bl/6J female mice received a daily oral dose of the MARBLES PCB mixture for two weeks prior to mating and through gestation and lactation. The mixture mimics the profile of PCBs found in a contemporary population of pregnant women. Voiding function was then tested in young adult offspring using void spot assay, uroflowmetry and anesthetized cystometry. PCB effects were sex and dose dependent. Overall, PCBs led to increases in small size urine spots in both sexes with males producing more drop-like voids and greater peak pressure during a voiding cycle while females displayed decreases in void duration and intervoid interval. Together, these results indicate that developmental exposure to PCBs are capable of altering voiding physiology in young adult mice. Further work to identify the underlying mechanisms driving these changes may help develop more effective preventative or therapeutic strategies for LUTS.

Keywords: Lower urinary tract; bladder; developmental origins of health and disease; persistent organic pollutants.

Figure 1

Developmental PCB exposure does not alter litter size, offspring body mass or urine specific gravity. Female mice were orally dosed with PCBs daily for two weeks prior to mating and all through gestation and lactation. PCBs did not alter (A) the number of days from first mating to litter date of birth, (B) litter size at birth, or (C) litter size at weaning. Developmentally exposed male and female offspring were weaned at P21 and aged to P47.7 ± 3.9. PCBs did not alter (D) male offspring body mass or (E) female offspring body mass. Free catch urine was collected from mice prior to collection and a refractometer used to measure (F, G) urine specific gravity in male and female offspring. Results are mean ± SEM. (A) n = 13-15 dams; (B, C) n = 10-15 litters; (D, E) n = 29-41 males, n = 27-49 females; (F, G) n = 12-24 males, n = 10-26 females. No significant differences were found as determined by one-way ANOVA, P < 0.05.

Figure 2

Developmental PCB exposure increases the proportion of frequent spotters and the number of small urine spots in male and female offspring. Mice were developmentally exposed to PCBs via the dam and VSA testing conducted on young adult male and female mice aged to P43.1 ± 1.4. Images of VSA for both male and female PCB dosage groups with urine spots in white (A). Parameters examined following the 4-hour VSA include (B, C) relative frequency (in % total), (D, E) frequent spotter percentage defined as 100 or 50+ urine spots, and (F, G) the urine spot size distribution. Results are mean ± SEM n = 17-24 males, n = 14-24 females. * indicates significant difference from vehicle control. P ≤ 0.05 were considered significant. A bar and * indicate significant differences as determined by: (D, E) Fisher’s exact test, and (F, G) Two-way ANOVA followed by Dunnett’s multiple comparisons test. The second y-axis denotes a change in scale so all data can be visualized on one graph.

Figure 3

Developmental PCB exposure alters urine area and percent urine area in center of female mice undergoing void spot assay (VSA). Mice were developmentally exposed to PCBs via the dam and VSA testing conducted on young adult male and female mice aged to P43.1 ± 1.4. Parameters examined following the 4-hour VSA include (A, B) total urine area, (C, D) percent of total urine area within center of VSA paper, (E, F) percent of total urine area within corners of VSA paper. Results are mean ± SEM n = 17-24 males, n = 14-24 females. * indicates significant difference from vehicle control. P < 0.05 as determined by: (A, D-F) Kruskal Wallis test followed by Dunn’s multiple comparisons test, (B) one-way ANOVA followed by Dunnett’s multiple comparison test, (C) one-way ANOVA on log transformed data.

Figure 4

Developmental PCB exposure decreases the stream rating in the male offspring in the 0.1 mg/kg males compared to 0 mg/kg males. Mice were developmentally exposed to PCBs via the dam and uroflowmetry testing conducted on young adult male and female mice aged to P45.9 ± 2.3. Examined parameters include (A, B) urine stream rating, (C, D) void mass, (E, F) void time, and (G, H) flow rate in mL/s. Results are mean ± SEM n = 15-24 males, n = 13-21 females. * indicates significant difference from vehicle control. P < 0.05 were considered significant as determined by: (A, B) Kruskal-Wallis test followed by Dunn’s multiple comparisons test, (C) Welch’s ANOVA on log transformed data, (D) Welch’s ANOVA, (E, H) One-way ANOVA on log transformed data, (F, G) One-way ANOVA.

Figure 5

Developmental PCB exposure decreases intervoid interval in female offspring and increases peak pressure in male offspring. Mice were developmentally exposed to PCBs via the dam and anesthetized cystometry conducted on young adult male and female mice aged to P49.4 ± 2.7. Examined parameters include (A, B) void duration, (C, D) intervoid interval, (E, F) normalized threshold pressure (threshold subtracted from baseline pressure), and (G, H) normalized peak pressure (peak subtracted from baseline pressure). (I, J) Representative cystometrograms. Results are mean ± SEM n = 6-10 males, n = 8-14 females. * indicates significant difference from vehicle control. P < 0.05 were considered significant as determined by: (A, C, G) One-way ANOVA followed by Dunnett’s multiple comparisons test, (B, F) One-way ANOVA followed by Dunnett’s multiple comparisons test on log transformed data, (D, H) Kruskal-Wallis test followed by Dunn’s multiple comparisons test, (E) Welch’s ANOVA.

Figure 6

Developmental PCB exposure does not alter non-voiding contractions and trends to decrease compliance in female offspring. Mice were developmentally exposed to PCBs via the dam and anesthetized cystometry conducted on young adult male and female mice aged to P49.4 ± 2.7. Examined parameters include (A, B) number of non-voiding contractions, (C, D) bladder compliance (change in volume/change in pressure). Results are mean ± SEM n = 6-10 males, n = 8-14 females. P < 0.05 were considered significant as determined by: (A, B, D) One-way ANOVA followed by Dunnett’s multiple comparisons test, (C) Welch’s ANOVA.