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Optimization of a pain model: effects of body temperature and anesthesia on bladder nociception in mice.

Sadler KE, Stratton JM, DeBerry JJ, Kolber BJ - PLoS ONE (2013)

Bottom Line: Distensions performed following the short anesthesia protocol were significantly different from one another despite identical testing parameters; this same effect was not observed when the long anesthesia protocol was used.These results highlight the significance of the dynamic effects of anesthesia on pain-like changes and the importance of close monitoring of temperature while performing UBD.For successful interpretation of VMRs and translation to human disease, body temperature should be maintained at 37.5°C and isoflurane induction should gradually decrease over the course of 90 minutes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences and Chronic Pain Research Consortium, Duquesne University, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating urological condition that is resistant to treatment and poorly understood. To determine novel molecular treatment targets and to elucidate the contribution of the nervous system to IC/BPS, many rodent bladder pain models have been developed. In this study we evaluated the effects of anesthesia induction and temperature variation in a mouse model of bladder pain known as urinary bladder distension (UBD). In this model compressed air is used to distend the bladder to distinct pressures while electrodes record the reflexive visceromotor response (VMR) from the overlying abdominal muscle. Two isoflurane induction models are commonly used before UBD: a short method lasting approximately 30 minutes and a long method lasting approximately 90 minutes. Animals were anesthetized with one of the methods then put through three sets of graded bladder distensions. Distensions performed following the short anesthesia protocol were significantly different from one another despite identical testing parameters; this same effect was not observed when the long anesthesia protocol was used. In order to determine the effect of temperature on VMRs, animals were put through three graded distension sets at 37.5 (normal mouse body temperature), 35.5, and 33.5°C. Distensions performed at 33.5 and 35.5°C were significantly lower than those performed at 37.5°C. Additionally, Western blot analysis revealed significantly smaller increases in spinal levels of phosphorylated extracellular-signal regulated kinase 2 (pERK2) following bladder distension in animals whose body temperature was maintained at 33.5°C as opposed to 37.5°C. These results highlight the significance of the dynamic effects of anesthesia on pain-like changes and the importance of close monitoring of temperature while performing UBD. For successful interpretation of VMRs and translation to human disease, body temperature should be maintained at 37.5°C and isoflurane induction should gradually decrease over the course of 90 minutes.

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Isoflurane induction method affects VMRs.Short anesthesia method (A) was used to perform UBD (n = 6). As time progressed, VMRs steadily decreased. Two-way ANOVA revealed a significant difference between sets (***p<0.0001), but not between pressures (p = 0.7364). Bonferroni's posttest yielded differences between sets 1 and 3 at 60 mmHg (***p<0.001) and 75 mmHg (**p<0.01). When long anesthesia method (B) was used to perform UBD (n = 6), two-way ANOVA revealed no main effect of set number (p = 0.8751), but did yield a significant main effect of pressure (*p = 0.0436).
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pone-0079617-g002: Isoflurane induction method affects VMRs.Short anesthesia method (A) was used to perform UBD (n = 6). As time progressed, VMRs steadily decreased. Two-way ANOVA revealed a significant difference between sets (***p<0.0001), but not between pressures (p = 0.7364). Bonferroni's posttest yielded differences between sets 1 and 3 at 60 mmHg (***p<0.001) and 75 mmHg (**p<0.01). When long anesthesia method (B) was used to perform UBD (n = 6), two-way ANOVA revealed no main effect of set number (p = 0.8751), but did yield a significant main effect of pressure (*p = 0.0436).

Mentions: To test the effects of induction time, two cohorts of animals were sedated by either the long or short anesthesia method. Nociceptive responses were then assessed through three sets of distensions; each set lasted approximately 30 min and consisted of 15 distensions at graded pressures (15–75 mmHg). Surprisingly, in animals that underwent short anesthesia, there was a statistically significant main effect of distension set number (e.g. 1 vs. 2 vs. 3) on the UBD-evoked VMR; the graded quality of VMRs diminished in sets 2 and 3 (Figure 2A; two-way ANOVA, p<0.0001). Additionally, Bonferroni's posttest revealed statistically significant differences between set 1, which ended approximately 1 hr post-surgery, and set 3, which ended approximately 2 hr post-surgery, at 60 and 75 mmHg (60 mmHg, p<0.001; 75 mmHg, p<0.01). In animals that underwent long anesthesia set number did not have a significant main effect on VMR (Figure 2B; two-way ANOVA, p = 0.8751). However, as expected, pressure did have a statistically significant main effect on UDB-evoked VMRs; VMRs increased as bladder pressure increased (two-way ANOVA, p<0.05). Overall, these data suggest that a longer anesthesia induction produces a more stable VMR to bladder distension.


Optimization of a pain model: effects of body temperature and anesthesia on bladder nociception in mice.

Sadler KE, Stratton JM, DeBerry JJ, Kolber BJ - PLoS ONE (2013)

Isoflurane induction method affects VMRs.Short anesthesia method (A) was used to perform UBD (n = 6). As time progressed, VMRs steadily decreased. Two-way ANOVA revealed a significant difference between sets (***p<0.0001), but not between pressures (p = 0.7364). Bonferroni's posttest yielded differences between sets 1 and 3 at 60 mmHg (***p<0.001) and 75 mmHg (**p<0.01). When long anesthesia method (B) was used to perform UBD (n = 6), two-way ANOVA revealed no main effect of set number (p = 0.8751), but did yield a significant main effect of pressure (*p = 0.0436).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3818235&req=5

pone-0079617-g002: Isoflurane induction method affects VMRs.Short anesthesia method (A) was used to perform UBD (n = 6). As time progressed, VMRs steadily decreased. Two-way ANOVA revealed a significant difference between sets (***p<0.0001), but not between pressures (p = 0.7364). Bonferroni's posttest yielded differences between sets 1 and 3 at 60 mmHg (***p<0.001) and 75 mmHg (**p<0.01). When long anesthesia method (B) was used to perform UBD (n = 6), two-way ANOVA revealed no main effect of set number (p = 0.8751), but did yield a significant main effect of pressure (*p = 0.0436).
Mentions: To test the effects of induction time, two cohorts of animals were sedated by either the long or short anesthesia method. Nociceptive responses were then assessed through three sets of distensions; each set lasted approximately 30 min and consisted of 15 distensions at graded pressures (15–75 mmHg). Surprisingly, in animals that underwent short anesthesia, there was a statistically significant main effect of distension set number (e.g. 1 vs. 2 vs. 3) on the UBD-evoked VMR; the graded quality of VMRs diminished in sets 2 and 3 (Figure 2A; two-way ANOVA, p<0.0001). Additionally, Bonferroni's posttest revealed statistically significant differences between set 1, which ended approximately 1 hr post-surgery, and set 3, which ended approximately 2 hr post-surgery, at 60 and 75 mmHg (60 mmHg, p<0.001; 75 mmHg, p<0.01). In animals that underwent long anesthesia set number did not have a significant main effect on VMR (Figure 2B; two-way ANOVA, p = 0.8751). However, as expected, pressure did have a statistically significant main effect on UDB-evoked VMRs; VMRs increased as bladder pressure increased (two-way ANOVA, p<0.05). Overall, these data suggest that a longer anesthesia induction produces a more stable VMR to bladder distension.

Bottom Line: Distensions performed following the short anesthesia protocol were significantly different from one another despite identical testing parameters; this same effect was not observed when the long anesthesia protocol was used.These results highlight the significance of the dynamic effects of anesthesia on pain-like changes and the importance of close monitoring of temperature while performing UBD.For successful interpretation of VMRs and translation to human disease, body temperature should be maintained at 37.5°C and isoflurane induction should gradually decrease over the course of 90 minutes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences and Chronic Pain Research Consortium, Duquesne University, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating urological condition that is resistant to treatment and poorly understood. To determine novel molecular treatment targets and to elucidate the contribution of the nervous system to IC/BPS, many rodent bladder pain models have been developed. In this study we evaluated the effects of anesthesia induction and temperature variation in a mouse model of bladder pain known as urinary bladder distension (UBD). In this model compressed air is used to distend the bladder to distinct pressures while electrodes record the reflexive visceromotor response (VMR) from the overlying abdominal muscle. Two isoflurane induction models are commonly used before UBD: a short method lasting approximately 30 minutes and a long method lasting approximately 90 minutes. Animals were anesthetized with one of the methods then put through three sets of graded bladder distensions. Distensions performed following the short anesthesia protocol were significantly different from one another despite identical testing parameters; this same effect was not observed when the long anesthesia protocol was used. In order to determine the effect of temperature on VMRs, animals were put through three graded distension sets at 37.5 (normal mouse body temperature), 35.5, and 33.5°C. Distensions performed at 33.5 and 35.5°C were significantly lower than those performed at 37.5°C. Additionally, Western blot analysis revealed significantly smaller increases in spinal levels of phosphorylated extracellular-signal regulated kinase 2 (pERK2) following bladder distension in animals whose body temperature was maintained at 33.5°C as opposed to 37.5°C. These results highlight the significance of the dynamic effects of anesthesia on pain-like changes and the importance of close monitoring of temperature while performing UBD. For successful interpretation of VMRs and translation to human disease, body temperature should be maintained at 37.5°C and isoflurane induction should gradually decrease over the course of 90 minutes.

Show MeSH
Related in: MedlinePlus