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Neurotransmitter Mechanisms Underlying Neuromodulation of Bladder Overactivit Changfeng Tai, Ph.D. Assistant Professor Department of Urology University of Pittsburgh
Neurotransmitter Mechanisms UnderlyingNeuromodulation of Bladder Overactivity
Changfeng Tai, Ph.D.Assistant Professor
Department of UrologyUniversity of Pittsburgh
Overactive Bladder - OAB
A syndrome characterized by urgency with or without urge incontinence, usually with frequency and nocturia
About 33.3 million adults suffer from OAB in US
Pathology and etiology - unknown
First-line pharmacotherapy - antimuscarinic drugs (tolterodine, or oxybutynin, etc.)
Low efficacy with side effects - dry mouth, constipation, headache, and blurred vision
An effective treatment is needed – high efficacy, less side effects, non-invasive
Currently neuromodulation is only used after the pharmacotherapy is failed.
Sacral neuromodulation and tibial neuromodulation – FDA approved for OAB
Sacral Neuromodulation Invasive – need surgery to implant a stimulator
Cost – more than $20K for surgery and stimulator
Efficacy – about 60-80% implanted patients have more than 50% improvement for 5-10 years
Acceptability – only 40,000 implantation worldwide, but 33.3 million adults suffer from OAB in United States
Limitation – mainly due to its invasiveness
Kessler TM and Fowler CJ (2008)Nat Clin Pract Urol doi:10.1038/ncpuro1251
Needle Electrode
Ruiz et al (2004) European Urology
Minimally invasive – needle insertion
Frequent clinic visit – 30 minutes/week for 12 weeks, then once per 2-3 weeks
Low efficacy – about same as antimuscarinic drugs
Tibial Neuromodulation
Clinical Setting
Our Hypothesis
Neuromodulation activates a specific group of afferent nerves to deliver neurotransmitters in the CNS to modulate the bladder activity Efficacy of neuromodulation therapy can be increased by enhancing the neurotransmitter mechanisms involved
Identify the neurotransmitters and receptors involved in neuromodulation therapies
Develop new, non-invasive, effective neuromodulation therapies
Our Goal
Images from "Anatomy of the Human Body" by Henry Gray
Sacral (S3)
Pudendal Nerve
Tibial Nerve
Sacral Neuromodulation(Sacral S3 Root)
Bladder
Brain/PAG/PMC
A-fiber
Spinal Cord
21
PudN /TibialN
C-fiber3
4
PudN = Pudendal nerveTibialN = Tibial NervePMC = Pontine micturition centerPAG = Periaqueductal grey1 = Inhibitory interneuron2 = Spinal tract neuron3 = Excitatory interneuron4 = Parasympathetic preganglionic Neuron
= Excitatory synapse= Inhibitory synapse= Neuron
1
Micturition Reflex Pathways and Animal Model
A-fiber --- bladder distention using saline C-fiber --- 0.25% acetic acid
Animal model – anesthetized cats
Neurotransmitters Involved in Pudendal Neuromodulation
Pudendal Neuromodulation – Acetic Acid Irritation
Jeffrey Larson, P. Dafe Oagagan, et al. (2011) Journal of Physiology60
cm
H2O
100 sec
Saline
AA
AA
AA
Start Infusion
1 T
4 T
Stop Infusion
StopInfusion
StopInfusion
StopInfusion
Saline 0.25% AA AA, 1T AA, 3-4T0
20
40
60
80
100
120
140
CMG Conditions
Nor
mal
ized
Cap
acity
(%)
0.1 mg/kg
1 mg/kg
3 mg/kg
10 mg/kg
30 mg/kg
50 mg/kg
0.3 mg/kg
1 T
1 T
1 T
1 T
1 T
1 T
1 T
4 T
4 T
4 T
4 T
4 T
4 T
4 T
MTEP(i.v.)
60
cmH
2O
100 sec
Pudendal Neuromodulation – mGluR5 ReceptorMTEP – Metabotropic glutamate receptor 5 (mGluR5) antagonist
Jeffrey Larson, P. Dafe Oagagan, et al. (2011) Journal of Physiology
0 0.1 0.3 1 3 10 30 500
20
40
60
80
100
120
140
AA, 1TAA, 3 - 4T
AA control
MTEP Dosage (mg/kg)
No
rmal
ized
Cap
acit
y (%
)
* * ** *
#
#
#
Jeffrey Larson, P. Dafe Oagagan, et al. (2011) Journal of Physiology
Pudendal Neuromodulation – mGluR5 Receptor
Pudendal Neuromodulation – Opioid Receptor
A. AA Control B. 1T C. 4T
BeforeNaloxone
0.1 mg/kg Naloxone
0.3 mg/kg Naloxone
1.0 mg/kgNaloxone Stop Infusion
200 sec
50 c
mH
2O
Start Infusion
Start Infusion
Start Infusion
0.0 0.1 0.3 1.00
25
50
75
100
125
1-1.5 T4T
AA ControlPost-stim
Naloxone Dosage (mg/kg)
Nor
mal
ized
Cap
acity
(%
)
* ***
****
###
#
Abhijith D. Mally, et al. (2013 in press) Journal of Urology
Naloxone – opioid receptor antagonist
Pudendal Neuromodulation – Serotonin 5HT2 Receptor
0 0.01 0.03 0.1 0.3 10
50
100
150
AA-Ctrl
PNS 1-2TPNS 3-4T
Methysergide Dosage (mg/kg)
Nor
mal
ized
Cap
acity
(%
)
*
*
*
*
* *
*
*
#
#
#
#
Methysergide – Serotonin 5HT2 receptor antagonist
FDA approved for treatment of headaches
Pudendal Neuromodulation – Serotonin 5HT3 Receptor
Ondansetron – Serotonin 5HT3 receptor antagonist
FDA approved for treatment of nausea and vomiting
0 0.003 0.01 0.03 0.1 0.3 1 30
50
100
150
AA Control
1.5T
3T
Ondansetron dosage (mg/kg)
Nor
mal
ized
Cap
acity
(%)
##
#
*
*
*
*
*
*
*
*
*
*
*
*
* *
Pudendal Neuromodulation – Multiple Neurotransmitters
Not involved:Opioid receptor
Partially involved:Metabotropic glutamate receptor 5Serotonin 5HT2 or 5HT3 receptor
A single major neurotransmitter or multiple neurotransmitters?
Neurotransmitters Involved in Tibial Neuromodulation
Tibial Neuromodulation – Acetic Acid Irritation
4TStop Infusion
8TStop Infusion
Stop Infusion
Stop Infusion
Stop Infusion
AA
AA
AA
AA
Saline
200 sec75 c
mH
2O*
Saline AA 4T 8T0
20
40
60
80
100
No
rma
lize
d C
ap
aci
ty (
%)
* *
StartInfusion
A
B
Changfeng Tai, et al. (2012) American Journal of Physiology - Renal Physiology
0.001 mg/kgNaloxone
0.01 mg/kgNaloxone
0.1 mg/kgNaloxone
1.0 mg/kgNaloxone
200 sec
50 c
mH
2O
No Naloxone
B. 4T C. 8TA. AA Control
Tibial Neuromodulation – Opioid Receptor
Changfeng Tai, et al. (2012) American Journal of Physiology - Renal Physiology
Tibial Neuromodulation – Opioid Receptor
0 0.001 0.01 0.1 10
100
200
300
400
500
4 T
8 T
AA Control
Naloxone Dosage (mg/kg)
No
rmal
ized
Cap
acit
y (%
)
*
*
**
#
#
200 sec
50 c
mH
2O
Stop Infusion
Stop Infusion
8T
AAControl
16TStop Infusion
Stop Infusion
AAControl
StartInfusion
Changfeng Tai, et al. (2012) American Journal of Physiology - Renal Physiology
Tibial Neuromodulation – Tramadol Enhancement
Tramadol – opioid receptor agonist
Fan Zhang, et al. (2012) American Journal of Physiology - Renal Physiology
Tramadol0 mg/kg
Stop Infusion 500 sec
100
cmH
2O
B. 2T C. 4T
StartInfusion
StartInfusion
StartInfusion
Tramadol0.3 mg/kg
Tramadol1 mg/kg
Tramadol3 mg/kg
Tramadol7 mg/kg
A. Before Stimulation
Tibial Neuromodulation – Tramadol Enhancement
Tramadol side effects: nausea, vomiting, dizziness, constipation
0 0.3 1.0 3.0 7.00
25
50
75
100
125
150
175
200
2T
4T
before stimulation
*
#
**
&
&
&
&
&
&
***
#
#
#
#
#
#
# #
#
no stimulation
&
&
** *
*
Tramadol Dosage(mg/kg)
No
rmal
ized
Cap
acit
y (%
)
Fan Zhang, et al. (2012) American Journal of Physiology - Renal Physiology
Tramadol 3 mg/kg
0 0.3 1.0 3.0 7.00
50
100
150
200
before stimulationafter stimulation
*
*
(1st) (2nd) (3rd) (4th) (5th)
Tramadol Dosage (mg/kg)N
orm
aliz
ed C
apac
ity
(%)
Stop Infusion
500 sec
100
cmH
2O
BA
4T
2T
StartInfusion
beforestimulation
afterstimulation
0.0 0.0 0.0 0.0 0.00
50
(1st) (2nd) (3rd) (4th) (5th)
Tramadol Dosage (mg/kg)No
rmal
ized
Cap
acit
y(%
)
C
Fan Zhang, et al. (2012) American Journal of Physiology - Renal Physiology
Tibial Neuromodulation – Tramadol and Post-Stimulation Inhibition
Tibial Neuromodulation – Tramadol and Post-Stimulation Inhibition
1st
2nd
3rd
4th
5th
control 1st 2nd 3rd 4th 5th0
50
100
150
200
* * * * *
CMGs
No
rmal
ized
Cap
acit
y(%
)
2T
4T
control
A. After 7 mg/kg Tramadol
StopInfusion
B. Post-stimulation Capacity Increasecontrol 10
0 cm
H2O
250 sec
StartInfusion
Fan Zhang, et al. (2012) American Journal of Physiology - Renal Physiology
BeforeLY341495
A. AA controlStart
infusion
0.1 mg/kgLY341495
0.3 mg/kgLY341495
1 mg/kgLY341495
3 mg/kgLY341495
5 mg/kgLY341495
B. 2T C. 4T
Stop infusion
100 sec75
cm
H2O
LY341495 – metabotropic glutamate receptor2/3 (mGluR2/3) antagonist
Tibial Neuromodulation – mGluR2/3 receptor
Tibial Neuromodulation – mGluR2/3 receptor
LY 341495 Dosage (mg/kg)
Nor
mal
ized
Cap
acity
(%
)
0 0.1 0.3 1 3 50
20
40
60
80
100
AA control
AA, 2T
AA, 4T
* * *
*
**
* **
##
##
#
Tibial Neuromodulation – Synergetic Interaction between mGluR2/3 and Opioid Receptors
100 sec
75 c
mH
2O
AA control
A. LY341495 pretreated
Startinfusion
Startinfusion
4T
BeforeNaloxone
0.001 mg/kgNaloxone
0.01 mg/kgNaloxone
B. No LY341495
Startinfusion
Startinfusion
AA control 4T
BeforeNaloxone
0.001 mg/kgNaloxone
0.01 mg/kgNaloxone
1 mg/kgNaloxone
0.1 mg/kgNaloxone
Stopinfusion
Stopinfusion
Stopinfusion
Stopinfusion
0 0.001 0.01 0.1 10
100
200
300
400
500
AA 4T TNSAA control + LY341495
AA control
AA 4T TNS + LY341495
Naloxone Dosage (mg/kg)
Nor
mal
ized
Cap
acity
(%) * *
*
**
##
C. Summary
Reduce Tramadol Dosage?
Neurotransmitters Involved in Foot Neuromodulation
Hindlimb
Ankle
Electrode #1
Electrode #2
Foot – Tibial Nerve
Tibial Nerve
Human Animal - Cat
Foot – Saline infusion
Control
5 Hz
20 H
z0
50
100
150
200
No
rmal
ized
Bla
dd
er C
apac
ity
(%)
**
StopControl
20 Hz
Control
5 Hz
Control
100 sec20
cm
H2O
StartInfusion
Stop
Stop
Stop
Stop
Changfeng Tai, et al. (2010) BJU International
Foot – Post-stimulation Effect (Saline)
Guoqing Chen, et al. (2012) Journal of Urology
Start Infusion
InitialCMG
1st
6th
2nd
7th
3rd
8th
4th
9th
5th
10th
A. Control B. Post-Stimulation Effect
200sec
200c
mH
2O
InitialCMG
1st
2nd
3rd
4th
5th
5Hz stimulation for 30 minutes
Isovolumetriccontractionsfor 30 minutes
Isovolumetriccontractionsfor 30 minutes
6th
7th
8th
9th
10thStop Infusion
Start Infusion
Stop Infusion
5Hz stimulation for 30 minutes
200sec
200c
mH
2O
Foot – Post-stimulation Effect (Saline)
Guoqing Chen, et al. (2012) Journal of Urology
1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th0
50
100
150
200
Control
Stimulation
Number of CMGs
No
rmal
ized
Bla
dd
er C
apac
ity
(%)
after 1st 30 min after 2nd 30 min
*
Saline Control
0.25% AA
0.25% AA
0.25% AA
0.25% AA
0.25% AA
StartInfusion
Stop
100 sec
40
cm
H2O
Stop
Stop
Stop
Stop
Stop
5 Hz
20 Hz
Foot – Acetic Acid Infusion
Salin
e
0.25
% A
A5
Hz
20 H
z0
25
50
75
100
No
rmal
ized
Bla
dd
er C
apac
ity
(%)
**
*
Changfeng Tai, et al. (2010) BJU International
No post-stimulation Effect
Start Infusion
Stop Infusion
Stop Infusion
Stop Infusion
Stop Infusion
Stop Infusion
Stop Infusion
4 T
4 T
8 T
Saline
0.25% AA
0.25% AA
0.25% AA
0.25% AA
0.25% AA
Naloxone1 mg/kg
100 sec
50 c
m H
2O
Foot – Opioid Receptor
Saline AA 4T
Naloxo
ne 4T6-
8T0
20
40
60
80
100
CMG Conditions
No
rma
lize
d B
lad
de
r C
ap
ac
ity
(%)
*
**
Changfeng Tai, et al. (2012) Journal of Urology
Foot – Tramadol Enhancement
Tramadol3 mg/kg
Tramadol 1 mg/kg 100 sec
50 c
mH
2O
2T
2T
2T
4T
4T
4T
A. Tramadol alone
BeforeTramadol
Stop Infusion
Start Infusion
B. Tramadol + Stimulation
C. Summary
BeforeTramadol
Tramadol 1 mg/kg
Tramadol3 mg/kg
0 1.0 3.00
50
100
150
200
TM + 2T
TM + 4T
TM alone
Tramadol Dosage (mg/kg)
No
rma
lize
d C
ap
aci
ty (
%)
*
**
#
# #
#
@
@
100 sec
50 c
mH
2O
Abhijith D. Mally, et al. (2012) Journal of Urology
Foot – Tramadol and Post-stimulation Effect
2T
4T
Start Infusion
Stop Infusion100 sec
50 c
mH
2O
Stop Infusion
Pre-Stimulation
Post-Stimulation
Increased Capacity
A After 3 mg/kg Tramadol
B*
0 0 00
50
Tramadol Dosage(mg/kg)No
rma
lize
d C
ap
aci
ty(%
)
C
#
##
0 1.0 3.00
50
100
150
200
Post-Stimulation
Pre-Stimulation
Tramadol Dosage(mg/kg)
No
rma
lize
d C
ap
aci
ty (
%)
Abhijith D. Mally, et al. (2012) Journal of Urology
Foot – Tramadol and Post-stimulation Effect
control 1st 2nd 3rd 4th 5th0
100
200
300
** *
* *
CMGs
No
rma
lize
d C
ap
ac
ity
(%)
B. Post-stimulation Capacity Increase
1st
2nd
3rd
4th
5th
control
StopInfusion
control
2 T
4 T
100 sec
75 c
mH
2O
StartInfusion
A. After 3 mg/kg Tramadol
Abhijith D. Mally, et al. (2012) Journal of Urology
Foot – Application to Human Subject
Skin Surface Electrodes
24 Hour Before Stim
1-5 Hour After Stim
5-24 Hour After Stim
0
100
200
300
400
500
600
700
Bla
dd
er
Vo
lum
e (
ml)
*
Stimulation: 1.5 hour duration, 5 Hz, 0.2 ms, 2-3T
Drinking water: 1000 ml during 1.5 hour stimulation
N = 4 subjects
Foot – A Shoe Stimulator for OAB
Embedded in the shoe
Combining with Tramadol Treatment?
Non-invasiveNo frequent clinic visitNo adverse effectHigh efficacy – continuous stimulation
Acknowledgement
Department of Pharmacology& Chemical BiologyUniversity of PittsburghXianchun Wang, M.D.Timothy Ungerer, B.S.James R. Roppolo, Ph.D.William C. de Groat, Ph.D.
National Institute of Diabetes & Digestive& Kidney Diseases (NIDDK)
Department of UrologyUniversity of PittsburghBing Shen, D.V.M.Jicheng Wang, Ph.D.Hailong Liu, Ph.D.Mang Chen, M.D.Jeffery Larson, M.D.P. Dafe Ogagan, M.D.Abhijith Dev Mally, M.D.Fan Zhang, M.D.Guoqing Chen, M.D.Shouguo Zhao, Ph.D.Shaohua Huang, Ph.D.Yosuke Matsuta, M.D., Ph.D.Zeyad Schwen, B.S.
Department of Defense (DOD)
Christopher and Dana Reeve Foundation
