Sympathetic Hyperactivity, Increased Tyrosine Hydroxylase and Exaggerated Corpus Cavernosum Relaxations Associated with Oxidative Stress Plays a Major Role in the Penis Dysfunction in Townes Sickle Cell Mouse

Abstract

BackgroundSickle cell disease patients display priapism that may progress to erectile dysfunction. However, little is known about the pathophysiological alterations of corpus cavernosum in sickle cell disease.ObjectiveThus, this study aimed to evaluate the functional and molecular alterations of sympathetic machinery and nitric oxide—cyclic guanosine monophosphate signaling pathway in Townes transgenic sickle cell disease mice.MethodsConcentration–response curves to contractile (phenylephrine) and relaxant agents (acetylcholine and sodium nitroprusside) were obtained in corpus cavernosum strips from sickle and C57BL/6 (control) mice. Neurogenic contractions and nitrergic relaxations were obtained using electrical-field stimulation. Measurements of endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), phosphodiesterase-5 (PDE5) and α1A-, α1B- and α1D-adrenoceptor mRNA expressions and reactive-oxygen species were performed. Tyrosine hydroxylase phosphorylated at Ser-31 and total tyrosine hydroxylase protein expressions in cavernosal tissues were also measured.ResultsThe neurogenic contractions were higher in the sickle cell disease group, in association with elevated tyrosine hydroxylase phosphorylated at Ser-31 and total tyrosine hydroxylase protein expression, as well as increased tyrosine hydroxylase mRNA expression. Likewise, phenylephrine-induced contractions were greater in the sickle mice, whereas α1A-, α1B- and α1D-adrenoceptor mRNA expression remained unchanged. Cavernosal relaxations to acetylcholine, sodium nitroprusside and EFS were higher in sickle mice, accompanied by decreased eNOS and nNOS, along with lower PDE5 mRNA expression. An increase of about 40% in reactive-oxygen species generation in corpus cavernosum from sickle mice was also detected.ConclusionOur study shows that decreased nitric oxide bioavailability in erectile tissue due to increased oxidative stress leads to both sympathetic hyperactivity and dysregulation of nitric oxide signaling in corpus cavernosum from Townes sickle mice.

Calpain inhibition improves erectile function in diabetic mice via upregulating endothelial nitric oxide synthase expression and reducing apoptosis

“…NO promotes the production of cyclic guanosine monophosphate (cGMP) in cavernosal smooth muscle cells, resulting in the relaxation of smooth muscle and subsequent penile erection. 6 Endothelial nitric oxide synthase (eNOS) is a major source of NO in the corpus cavernosum. 7 8 Endothelial dysfunction was reported to occur in both diabetic patients and diabetic animal models.…”

TSPO ligand FGIN‐1‐27 controls priapism in sickle cell mice via endogenous testosterone production

“…Another mouse model of SCD, the Townes SCD mouse, was developed by the replacement of the mouse α‐globin genes by human α‐globin genes and mouse β‐globin genes by human Aγ and βS globin genes (Wu et al, 2006). While these mice also exhibit a priapism phenotype, as shown in one study (Silva et al, 2016), they are not well characterized for this purpose. Second, we acknowledge the limitation of the mouse species for studying spermatogenesis, because the mouse lacks androgen‐binding protein in the testis and does not require high intratesticular T, as required for humans or other mammalian species (Wang et al, 1989).…”

D-(+)-Galactose-induced aging: A novel experimental model of erectile dysfunction

“…NO is another important factor and plays a key role in corpus cavernosum tonus regulation. Changes in NO synthesis or bioavailability can favor corpus cavernosum contraction, and consequently the development of ED [ 40 ]. We therefore evaluated whether NO release was affected by the treatments due to the action of ACh in the endothelial cells.…”