Immunohistochemical staining for nerve fascicles:

Immunostains against S-100 protein (Marker for Schwann and sustentacular cells), neurofilament protein (Marker for neurons and ganglion cells), and glial fibrillary acidic protein (GFAP: Marker for glial cells) are used for the recognition of nerve fascicles (20), whereas stains targeted at tyrosine hydroxylase (TH; which converts tyrosine to DOPA) are used for the presence or absence of norepinephrine synthesis (21). Although DOPA decarboxylase (which converts DOPA to dopamine) is another catecholamine-synthesizing enzyme, immunostaining against DOPA decarboxylase is rarely used in the area of renal denervation because DOPA decarboxylase positive fibers are more sparsely distributed than TH positive fibers in perivascular nerves in the kidney. The combination of at least one axonal marker (S-100 protein, neurofilament protein, or GFAP) and a functional marker (TH) may provide meaningful insights into the functional relevance of ablative treatment against resistent hypertension.

 To identify renal afferent nerves, immunostains against calcitonin gene-related peptide (CGRP) and Substance P, which serve as neurotransmitters in sensory nerves , have been reported in the literature. However, since immunostaining for CGRP using color-producing reagents has been reported to result in low intensity, the more reliably strong intensity of TH is most offen adopted for staining of efferent sympathetic nerve fibers in the immunohistochemical assessment of successful ablation of peri-arterial sympathetic nerves . Most importantly, the intensity of color reaction has been shown to be correlated with presence of viable efferent sympathetic nerve fibers using TH staining , an association not found with other immunostain procedures such as CGRP or substance P.

Article Methodological Standardization for the Pre-Clinical Evaluati...

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