The cGMP-degrading enzyme phosphodiesterase-5 (PDE5) in cerebral small arteries of older people

Abstract

Cerebral small vessel disease in deep penetrating arteries is a major cause of lacunar infarcts, white matter lesions and vascular cognitive impairment. Local cerebral blood flow in these small vessels is controlled by endothelial-derived nitric oxide, which exerts a primary vasodilator stimulus on vascular myocytes, via cytoplasmic cyclic GMP. Here, we investigated whether the cGMP-degrading enzyme phosphodiesterase-5 (PDE5) is present in small penetrating arteries in the deep subcortical white matter of older people. Frontal cortical tissue blocks were examined from donated brains of older people (n ¼ 42, 24 male: 18 female, median age 81, range: 59–100 years). PDE5, detected by immunohistochemical labeling, was graded as absent, sparse, or abundant in vascular cells within small arteries in subcortical white matter (vessel outer diameter: 20–100 mm). PDE5 labeling within arterial myocytes was detected in all cases. Degree of PDE5 expression (absent, sparse, or abundant) was not associated with age or with neuropathological diagnosis of small vessel disease. In conclusion, PDE5 is present in vascular myocytes within small penetrating arteries in older people. This is a potential molecular target for pharmacological interventions.