scholarly journals Bimodal effect of oxidative stress in internal anal sphincter smooth muscle

2015 ◽  
Vol 309 (5) ◽  
pp. G292-G300 ◽  
Author(s):  
Jagmohan Singh ◽  
Sumit Kumar ◽  
Satish Rattan
Keyword(s):  
Oxidative Stress ◽  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Rho Kinase ◽  
Inhibitory Effects ◽  
Ly 83583 ◽  
Nanc Relaxation ◽  
Rock Activity ◽  
Nnos Inhibition

Changes in oxidative stress may affect basal tone and relaxation of the internal anal sphincter (IAS) smooth muscle in aging. We examined this issue by investigating the effects of the oxidative stress inducer 6-anilino-5,8-quinolinedione (LY-83583) in basal as well as U-46619-stimulated tone, and nonadrenergic, noncholinergic (NANC) relaxation in rat IAS. LY-83583, which works via generation of reactive oxygen species in living cells, produced a bimodal effect in IAS tone: lower concentrations (0.1 nM to 10 μM) produced a concentration-dependent increase, while higher concentrations (50–100 μM) produced a decrease in IAS tone. An increase in IAS tone by lower concentrations was associated with an increase in RhoA/Rho kinase (ROCK) activity. This was evident by the increase in RhoA/ROCK in the particulate fractions, in ROCK activity, and in the levels of phosphorylated (p) Thr696-myosin phosphatase target subunit 1 and pThr18/Ser19-20-kDa myosin light chain. Conversely, higher concentrations of LY-83583 produced inhibitory effects on RhoA/ROCK. Interestingly, both the excitatory and inhibitory effects of LY-83583 in the IAS were reversed by superoxide dismutase. The excitatory effects of LY-83583 were found to resemble those with neuronal nitric oxide synthase (nNOS) inhibition by l-NNA, since it produced a significant increase in the IAS tone and attenuated NANC relaxation. These effects of LY-83583 and l-NNA were reversible by l-arginine. This suggests the role of nNOS inhibition and RhoA/ROCK activation in the increase in IAS tone by LY-83583. These data have important implications in the pathophysiology and therapeutic targeting of rectoanal disorders, especially associated with IAS dysfunction.

Sa1349 Bimodal Effect of Oxidative Stress in Internal Anal Sphincter (IAS) Smooth Muscle

2015 ◽  
Vol 148 (4) ◽  
pp. S-299
Author(s):  
Sumit Kumar ◽  
Jagmohan Singh ◽  
Satish C. Rattan
Keyword(s):  
Oxidative Stress ◽  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter

scholarly journals BDNF augments rat internal anal sphincter smooth muscle tone via RhoA/ROCK signaling and nonadrenergic noncholinergic relaxation via increased NO release

2020 ◽  
Vol 318 (1) ◽  
pp. G23-G33
Author(s):  
Arjun Singh ◽  
Ipsita Mohanty ◽  
Jagmohan Singh ◽  
Satish Rattan
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Anal Sphincter ◽  
Guanylate Cyclase ◽  
Internal Anal Sphincter ◽  
Soluble Guanylate Cyclase ◽  
Muscle Tone ◽  
Tyrosine Kinase Receptor ◽  
Therapeutic Targeting ◽  
Nanc Relaxation

Presently, there are no studies examining the neuromodulatory effects of brain-derived neurotropic factor (BDNF) on the basal internal anal sphincter (IAS) tone and nonadrenergic noncholinergic (NANC) relaxation. To examine this, we determined the neuromuscular effects of BDNF on basal IAS smooth muscle tone and the smooth muscle cells (SMCs) and the effects of NANC nerve stimulation before and after high-affinity receptor tyrosine kinase receptor B (TrkB) antagonist K252a. We also investigated the mechanisms underlying BDNF-augmented increase in the IAS tone and NANC relaxation. We found that BDNF-increased IAS tone and SMC contractility were TTX resistant and attenuated by K252a. TrkB-specific agonist 7,8-dihydroxyflavone, similar to BDNF, also produced a concentration-dependent increase in the basal tone, whereas TrkB inhibitors K252a and ANA-12 produced a decrease in the tone. In addition, BDNF produced leftward shifts in the concentration-response curves with U46619 and ANG II (but not with bethanechol and K+ depolarization), and these shifts were reversed by K252a. Effects of Y27632 and Western blot data indicated that the BDNF-induced increase in IAS tone was mediated via RhoA/ROCK. BDNF-augmented NANC relaxation by electrical field stimulation was found to be mediated via the nitric oxide (NO)/soluble guanylate cyclase (sGC) pathway rather than via increased sensitivity to NO. In conclusion, the net effect of BDNF was that it caused an increase in the basal IAS tone via RhoA/ROCK signaling. BDNF also augmented NANC relaxation via NO/sGC. These findings may have relevance to the role of BDNF in the pathophysiology and therapeutic targeting of the IAS-associated rectoanal motility disorders. NEW & NOTEWORTHY These studies for the first time to our knowledge demonstrate that increased levels of brain-derived neurotrophic factor (BDNF; conceivably released from smooth muscle cells and/or the enteric neurons) has two major effects. First, BDNF augments the internal anal sphincter (IAS) tone via tyrosine kinase receptor B/thromboxane A2-receptor, angiotensin II receptor type 1/RhoA/ROCK signaling; and second, it increases nonadrenergic noncholinergic relaxation via nitric oxide/soluble guanylate cyclase. These studies may have relevance in therapeutic targeting in the anorectal motility disorders associated with the IAS.

BDNF rescues aging-associated internal anal sphincter dysfunction

2021 ◽  
Author(s):  
Arjun Singh ◽  
Satish Rattan
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Muscle Tone ◽  
Age Groups ◽  
Tyrosine Kinase Receptor ◽  
Inhibitory Neurotransmitter ◽  
Before And After ◽  
Neurotropic Factor ◽  
Nanc Relaxation

Aging can lead to rectoanal incontinence due to internal anal sphincter (IAS) dysfunction, which is characterized by a decrease in IAS tone and contractility and an increase in non-adrenergic non-cholinergic (NANC) relaxation. We aimed to determine whether brain-derived neurotropic factor (BDNF) rescues this aging-associated IAS dysfunction (AAID). To do so, we studied the effects of BDNF on the basal and GPCR-stimulated IAS smooth muscle tone and on NANC relaxation in in Fischer 344 rats representing different age groups (26-month-old [aging] vs. 6-month-old [young]), before and after tyrosine kinase receptor B (TrkB) antagonist K252a. We also used isolated smooth muscle cells (SMCs) to determine the effects of BDNF before and after different agonists. For some studies, we monitored NO release using smooth muscle perfusates. BDNF reversed AAID by rescuing the basal IAS tone and agonists (U46619 and Ang II)-induced contractility, and NANC relaxation. These rescue effects of BDNF were selective since K252a attenuated the changes in the IAS without modifying the effects of K+-depolarization. Because of the direct association between the basal and GPCR-stimulated IAS tone and RhoA/ROCK activation, we speculate that this pathway in the rescue effects of BDNF. Conversely, our data suggest that aging-associated increased NANC relaxation is reversed by decreased release of NO and decrease in the sensitivity of the released inhibitory neurotransmitter. In summary, BDNF rescue of AAID involves RhoA/ROCK and inhibitory neurotransmission. These data have direct implications for the role of BDNF in the pathophysiology and therapeutic targeting of aging-associated rectoanal motility disorders.

scholarly journals Rhythmic calcium transients in smooth muscle cells of the mouse internal anal sphincter

2019 ◽  
Vol 32 (3) ◽  
Author(s):  
Caroline A. Cobine ◽  
Karen I. Hannigan ◽  
Megan McMahon ◽  
Emer P. Ni Bhraonain ◽  
Salah A. Baker ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Muscle Cells ◽  
Calcium Transients

scholarly journals Aging-associated changes in microRNA expression profile of internal anal sphincter smooth muscle: Role of microRNA-133a

2016 ◽  
Vol 311 (5) ◽  
pp. G964-G973 ◽  
Author(s):  
Jagmohan Singh ◽  
Ettickan Boopathi ◽  
Sankar Addya ◽  
Benjamin Phillips ◽  
Isidore Rigoutsos ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Smooth Muscles ◽  
Smooth Muscle Contractility ◽  
Network Analyses ◽  
Rhoa Signaling

A comprehensive genomic and proteomic, computational, and physiological approach was employed to examine the (previously unexplored) role of microRNAs (miRNAs) as regulators of internal anal sphincter (IAS) smooth muscle contractile phenotype and basal tone. miRNA profiling, genome-wide expression, validation, and network analyses were employed to assess changes in mRNA and miRNA expression in IAS smooth muscles from young vs. aging rats. Multiple miRNAs, including rno-miR-1, rno-miR-340-5p, rno-miR-185, rno-miR-199a-3p, rno-miR-200c, rno-miR-200b, rno-miR-31, rno-miR-133a, and rno-miR-206, were found to be upregulated in aging IAS. qPCR confirmed the upregulated expression of these miRNAs and downregulation of multiple, predicted targets ( Eln, Col3a1, Col1a1, Zeb2, Myocd, Srf, Smad1, Smad2, Rhoa/Rock2, Fn1, Tagln v2, Klf4, and Acta2) involved in regulation of smooth muscle contractility. Subsequent studies demonstrated an aging-associated increase in the expression of miR-133a, corresponding decreases in RhoA, ROCK2, MYOCD, SRF, and SM22α protein expression, RhoA-signaling, and a decrease in basal and agonist [U-46619 (thromboxane A2analog)]-induced increase in the IAS tone. Moreover, in vitro transfection of miR-133a caused a dose-dependent increase of IAS tone in strips, which was reversed by anti-miR-133a. Last, in vivo perianal injection of anti-miR-133a reversed the loss of IAS tone associated with age. This work establishes the important regulatory effect of miRNA-133a on basal and agonist-stimulated IAS tone. Moreover, reversal of age-associated loss of tone via anti-miR delivery strongly implicates miR dysregulation as a causal factor in the aging-associated decrease in IAS tone and suggests that miR-133a is a feasible therapeutic target in aging-associated rectoanal incontinence.

A comparison of the contractile properties of smooth muscle from pig urethra and internal anal sphincter

2010 ◽  
Vol 29 (7) ◽  
pp. 1326-1331 ◽  
Author(s):  
Thanesan Ramalingam ◽  
N. Tugba Durlu-Kandilci ◽  
Alison F. Brading
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Contractile Properties

Use of Smooth Muscle Plasty After Intersphincteric Rectal Resection to Replace a Partially Resected Internal Anal Sphincter: Long-Term Follow-Up

2009 ◽  
Vol 52 (11) ◽  
pp. 1895-1901 ◽  
Author(s):  
Osman Krand ◽  
Tunç Yalti ◽  
Gurkan Tellioglu ◽  
Melih Kara ◽  
Ibrahim Berber ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Rectal Resection ◽  
Long Term Follow Up

CGRP and ANF cause relaxation of opossum internal anal sphincter via different mechanisms

1991 ◽  
Vol 260 (5) ◽  
pp. G764-G769 ◽  
Author(s):  
S. Rattan ◽  
C. Moummi ◽  
S. Chakder
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Cyclic Nucleotides ◽  
Internal Anal Sphincter ◽  
Camp Content ◽  
Calcitonin Gene ◽  
Before And After ◽  
Camp And Cgmp

This investigation examined and compared the role of cyclic nucleotides in the mediation of internal anal sphincter (IAS) relaxation caused by the addition of neuropeptide calcitonin gene-related peptide (CGRP) and atrial natriuretic factor (ANF). The studies were performed in vitro on smooth muscle strips of opossum IAS. The relaxation produced by CGRP and ANF was examined before and after the addition of tetrodotoxin (TTX) (1 x 10(-6)M). At this concentration, TTX did not have any significant effect on the relaxation produced by either CGRP or ANF, suggesting that these peptides act directly on the smooth muscle. Addition of CGRP (3 x 10(-6) M) produced the maximal relaxation and significantly increased cAMP content without changing cGMP. On the other hand, addition of ANF (3 x 10(-6) M) caused a similar fall in IAS tension that was accompanied by a significant elevation in cGMP without any change in cAMP content. The rises in the levels of cyclic nucleotides preceded the onset of fall in the resting tension of IAS. Our results demonstrate that CGRP and ANF relax isolated strips of opossum IAS by their action directly at the smooth muscle and that this relaxation is associated with an increase in cAMP and cGMP, respectively. The studies suggest the presence of both cAMP and cGMP pathways in the IAS and that the relaxation of IAS smooth muscle in response to different peptides may occur via a specific intracellular biochemical pathway.

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