Nicotinamide Riboside Alleviates Corneal and Somatic Hypersensitivity Induced by Paclitaxel in Male Rats

Abstract

Purpose Patients receiving chemotherapy may experience ocular discomfort and dry eye–like symptoms; the latter may be neuropathic in nature. This study assessed corneal and somatic hypersensitivity in male rats treated with paclitaxel and whether it was relieved by nicotinamide riboside (NR). Methods Corneal sensitivity to tactile and chemical stimulation, basal tear production, and sensitivity of the hindpaw to tactile and cool stimuli were assessed before and after paclitaxel in the absence and presence of sustained treatment with 500 mg/kg per os NR. Corneal nerve density and hindpaw intraepidermal nerve fiber (IENF) density were also examined. Results Paclitaxel-treated rats developed corneal hypersensitivity to tactile stimuli, enhanced sensitivity to capsaicin but not hyperosmolar saline, and increased basal tear production. Corneal nerve density visualized with anti–β-tubulin or calcitonin gene-related peptide (CGRP) was unaffected. Paclitaxel induced tactile and cool hypersensitivity of the hindpaw and a loss of nonpeptidergic hindpaw IENFs visualized with anti-protein gene product (PGP) 9.5 and CGRP. NR reversed tactile hypersensitivity of the cornea without suppressing tear production or chemosensitivity; it did not alter corneal afferent density. NR also reversed tactile and cool hypersensitivity of the hindpaw without reversing the loss of hindpaw IENFs. Conclusions These findings suggest that paclitaxel may be a good translational model for chemotherapy-induced ocular discomfort and that NR may be useful for its relief. The ability of NR to relieve somatic tactile hypersensitivity independent of changes in sensory nerve innervation suggests that reversal of terminal arbor degeneration is not critical to the actions of NR.

Nicotinamide Riboside, a Promising Vitamin B3 Derivative for Healthy Aging and Longevity: Current Research and Perspectives

“…In male rats, NR oral treatment (500 mg/kg) alleviated PTX-induced corneal and somatic hypersensitivity to tactile stimuli, with no suppression of basal tear production/chemosensitivity and without altering the corneal afferent density. NR also reversed the PTX-induced hindpaw hypersensitivity to cool and tactile stimuli, with no inverting of the non-peptidergic intraepidermal nerve fiber (IENF) loss [ 65 ].…”

Current and Emerging Pharmacotherapeutic Interventions for the Treatment of Peripheral Nerve Disorders

“…While this seems to conflict with a previously discussed study showing axonal protection with NAMPT stimulators (P7C3-A20) [ 197 ], NMN levels were not measured in that study, and it is possible that additional downstream pathways may have been involved, including subsequent NAD + production. More recently, nicotinamide riboside has also been shown to reverse both corneal and hindpaw mechanical hypersensitivity induced by paclitaxel in tumour-bearing rats, although the loss of intraepidermal nerve fibres was not alleviated [ 200 ].…”