Abstract
Background and Purpose: Endothelin-1 (ET-1) and Nucleotide
Oligomerization Domain-Like Receptor Family, Pyrin Domain Containing 3
(NLRP3) play an essential role in erectile dysfunction. ET-1 and NLRP3
activate inflammatory processes by increasing calcium
(Ca2+) and reactive oxygen species (ROS). In the
present study, we hypothesized that endothelin receptors
(ETA and ETB) stimulation, through
increased calcium and ROS formation, leads to NLRP3 activation.
Experimental approach: Intracavernosal pressure (ICP/MAP) was
measured in C57BL/6 (WT) mice. Functional and immunoblotting assays were
performed in corpora cavernosa (CC) strips from WT,
NLRP3-/- and caspase-/- mice after
ET-1 (100 nM) stimulation in the presence of vehicle, MCC950, tiron,
BAPTA AM, BQ123, or BQ788. Key Results: ET-1 gradually reduced
the ICP/MAP in WT mice, and MCC950 administration prevented the effect
of ET-1. ET-1 decreased CC relaxation to ACh and sodium nitroprusside
(SNP) and increased caspase-1 protein expression, effects reversed by
the ETA receptor antagonist BQ123. The
ETB receptor antagonist BQ788 also reversed the effect
of ET-1 on ACh and SNP relaxation. Additionally, tiron, BAPTA AM, and
NLRP3 genetic deletion prevented the ET-1-induced loss of ACh and SNP
relaxation. Moreover, BQ123 diminished CC caspase-1 expression, while
BQ788 increased caspase-1 and IL-1β levels in a concentration-dependent
manner (100 nM to 10 µM). Furthermore, tiron and BAPTA AM prevented
ET-1-induced increase in caspase-1. In addition, BAPTA AM blocked
ET-1-induced ROS generation. Conclusion and Implications: NLRP3
activation contributes to acute ET-1-induced erectile dysfunction by
mechanisms that depend on ETA- and
ETB-induced Ca2+ influx and ROS
generation.