Bizhan R Sharopov1, Kseniya L Gulak2, Igor B Philyppov2, Anna V Sotkis2, Yaroslav M Shuba3. 1. Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology NASU, Bogomotetz Str., 4, Kyiv 01024, Ukraine; Department of Biology, Faculty of Natural Sciences, National University of «Kyiv-Mohyla Academy», Skovoroda Str., 2, Kyiv 04655, Ukraine. Electronic address: sharopov@biph.kiev.ua. 2. Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology NASU, Bogomotetz Str., 4, Kyiv 01024, Ukraine. 3. Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology NASU, Bogomotetz Str., 4, Kyiv 01024, Ukraine. Electronic address: yshuba@biph.kiev.ua.
Abstract
AIMS: More than half of diabetic patients experience voiding disorder termed diabetic urinary bladder dysfunction (DBD). Here we have investigated how the alterations in transient receptor potential vanilloid 1 (TRPV1) ion channel expressed in bladder-innervating afferents may contribute to DBD pathogenesis. MAIN METHODS: The rat model of streptozotocin (STZ)-induced diabetes was used. The functional profile of TRPV1 in retrogradely labeled afferent, bladder-innervating dorsal root ganglia (DRG) neurons was examined using patch clamp. The level of TRPV1 transcripts in DRG was assessed with qRT-PCR. TRPV1-dependent component of detrusor smooth muscle (DSM) contractions was studied with muscle strip tensiometry. KEY FINDINGS: TRPV1-mediated current (ITRPV1) was increased in diabetic animals vs. controls by 42%. The expression of Trpv1 gene was found to be 63% higher in STZ-treated rats compared to controls, consistent with the respective electrophysiological data. Surprisingly, capsaicin-induced contractions of DSM were found to be 3-to-10-fold weaker in diabetic group depending on concentration of the agonist (100nM to 10μM). SIGNIFICANCE: Our findings suggest the dual role of TRPV1 in DBD. On the one hand, the increase of its functional expression may enhance micturition reflex arc functioning. On the other hand, at the local level, the decrease of TRPV1-dependent contractions may contribute to organ decompensation.
AIMS: More than half of diabeticpatients experience voiding disorder termed diabetic urinary bladder dysfunction (DBD). Here we have investigated how the alterations in transient receptor potential vanilloid 1 (TRPV1) ion channel expressed in bladder-innervating afferents may contribute to DBD pathogenesis. MAIN METHODS: The rat model of streptozotocin (STZ)-induced diabetes was used. The functional profile of TRPV1 in retrogradely labeled afferent, bladder-innervating dorsal root ganglia (DRG) neurons was examined using patch clamp. The level of TRPV1 transcripts in DRG was assessed with qRT-PCR. TRPV1-dependent component of detrusor smooth muscle (DSM) contractions was studied with muscle strip tensiometry. KEY FINDINGS:TRPV1-mediated current (ITRPV1) was increased in diabetic animals vs. controls by 42%. The expression of Trpv1 gene was found to be 63% higher in STZ-treated rats compared to controls, consistent with the respective electrophysiological data. Surprisingly, capsaicin-induced contractions of DSM were found to be 3-to-10-fold weaker in diabetic group depending on concentration of the agonist (100nM to 10μM). SIGNIFICANCE: Our findings suggest the dual role of TRPV1 in DBD. On the one hand, the increase of its functional expression may enhance micturition reflex arc functioning. On the other hand, at the local level, the decrease of TRPV1-dependent contractions may contribute to organ decompensation.
Authors: Nathan R Tykocki; Thomas J Heppner; Cuixia Shi Erickson; Jason van Batavia; Margaret A Vizzard; Mark T Nelson; Gerald C Mingin Journal: Am J Physiol Renal Physiol Date: 2018-08-08