TY - JOUR
T1 - Loss of caveolin-1 expression is associated with disruption of muscarinic cholinergic activities in the urinary bladder
AU - Lai, H. Henry
AU - Boone, Timothy B.
AU - Yang, Guang
AU - Smith, Christopher P.
AU - Kiss, Susanna
AU - Thompson, Timothy C.
AU - Somogyi, George T.
N1 - Funding Information:
We would like to thank Drs. Terry L Timme and Taoyah Men for preparation of animals. Supported by NIH grants DK45741 and CA84296.
PY - 2004/12
Y1 - 2004/12
N2 - Caveolin-1 (Cav1), a structural protein of caveolae, plays cell- and context-dependent roles in signal transduction pathway regulation. We have generated a knockout mouse homozygous for a null mutation of the Cav1 gene. Cav1 knockout mice exhibited impaired urinary bladder contractions in vivo during cystometry. Contractions of male bladder strips were evoked with electric and pharmacologic stimulation (5-40 Hz, 1-10 μM carbachol, 10 mM α,β-methylene ATP, 100 mM KCl). Acetylcholine (ACh) and norepinephrine (NE) release from bladder strips were measured with a radiochemical method by incubating the strips with 14C-choline and 3H-NE prior to electric stimulation, whereas ATP release was measured using the luciferin-luciferase assay with a luminometer. A 60-75% decline in contractility was observed when Cav1 knockout muscle strips were stimulated with electric current or carbachol, compared to wildtype muscle strips. No difference in contractility was noted when contractions were evoked either by the purinergic agonist α,β-methylene ATP, or by extracellular potassium. To investigate the relative contribution of non-cholinergic activity to bladder contractility, the amplitude of the electric stimulation-evoked contractions was compared in the presence of the muscarinic antagonist atropine (1 μM). While the non-muscarinic (purinergic) response was unaltered, muscarinic cholinergic response was principally disrupted in Cav1 knockout mice. The loss of Cav1 gene expression was also associated with a 70% reduction in ACh release. NE and ATP release was not altered. It is concluded that the loss of caveolin-1 is associated with disruption of M 3 muscarinic cholinergic activity in the bladder. Both pre-junctional (acetylcholine neurotransmitter release from neuromuscular junctions) and post-junctional (M 3 receptor-mediated signal transduction in bladder smooth muscles) mechanisms are disrupted, resulting in impaired bladder contraction.
AB - Caveolin-1 (Cav1), a structural protein of caveolae, plays cell- and context-dependent roles in signal transduction pathway regulation. We have generated a knockout mouse homozygous for a null mutation of the Cav1 gene. Cav1 knockout mice exhibited impaired urinary bladder contractions in vivo during cystometry. Contractions of male bladder strips were evoked with electric and pharmacologic stimulation (5-40 Hz, 1-10 μM carbachol, 10 mM α,β-methylene ATP, 100 mM KCl). Acetylcholine (ACh) and norepinephrine (NE) release from bladder strips were measured with a radiochemical method by incubating the strips with 14C-choline and 3H-NE prior to electric stimulation, whereas ATP release was measured using the luciferin-luciferase assay with a luminometer. A 60-75% decline in contractility was observed when Cav1 knockout muscle strips were stimulated with electric current or carbachol, compared to wildtype muscle strips. No difference in contractility was noted when contractions were evoked either by the purinergic agonist α,β-methylene ATP, or by extracellular potassium. To investigate the relative contribution of non-cholinergic activity to bladder contractility, the amplitude of the electric stimulation-evoked contractions was compared in the presence of the muscarinic antagonist atropine (1 μM). While the non-muscarinic (purinergic) response was unaltered, muscarinic cholinergic response was principally disrupted in Cav1 knockout mice. The loss of Cav1 gene expression was also associated with a 70% reduction in ACh release. NE and ATP release was not altered. It is concluded that the loss of caveolin-1 is associated with disruption of M 3 muscarinic cholinergic activity in the bladder. Both pre-junctional (acetylcholine neurotransmitter release from neuromuscular junctions) and post-junctional (M 3 receptor-mediated signal transduction in bladder smooth muscles) mechanisms are disrupted, resulting in impaired bladder contraction.
KW - Acetylcholine
KW - Caveolin-1
KW - Noradrenaline
UR - http://www.scopus.com/inward/record.url?scp=4544233451&partnerID=8YFLogxK
U2 - 10.1016/j.neuint.2004.06.016
DO - 10.1016/j.neuint.2004.06.016
M3 - Article
C2 - 15380628
AN - SCOPUS:4544233451
SN - 0197-0186
VL - 45
SP - 1185
EP - 1193
JO - Neurochemistry International
JF - Neurochemistry International
IS - 8
ER -