Kaempferol and zinc gluconate mitigate neurobehavioral deficits and oxidative stress induced by noise exposure in Wistar rats.

Joseph Olusegun Ayo,Firas H. Kobeissy,Victor Olusegun Sinkalu,Isaac Oluwatobi Akefe

doi:10.1371/journal.pone.0236251

Abstract

This study investigated the effects of kaempferol and zinc gluconate on neurobehavioural and oxidative stress changes in Wistar rats exposed to noise. Thirty (30) rats were randomly divided into five groups: Groups I and II were administered with deionized water (DW); Group III, kaempferol (K); Group IV, zinc gluconate (Zn); Group V, kaempferol + zinc gluconate. Groups II, III, IV, and V were subjected to noise stress (N) induced by exposing rats to 100 dB (4 h/day) for 15 days, from day 33 to day 48 after starting the drug treatments. Neuromuscular coordination, motor coordination, motor strength, sensorimotor reflex, and learning and memory, were evaluated using standard laboratory methods. Levels of nitric oxide (NO), malondialdehyde (MDA) and activities of glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD) were evaluated in the hippocampus. Exposure of rats to noise, induced significant neurobehavioural deficits and oxidative stress while the combined administration of kaempferol and zinc gluconate significantly (P < 0.05) improved open-field performance, motor coordination, motor strength, sensorimotor reflex, and learning and memory. Co-administration of kaempferol and zinc gluconate ameliorated noise-induced oxidative stress as demonstrated by the significantly increased activities of GPx, catalase, and SOD, and decreased levels of NO and MDA (P < 0.05 and P < 0.01 respectively), compared to the DW + N group. Our results suggest that oxidative stress, evidenced by increased NO and MDA concentration and decreased activities of GPx, catalase and SOD, were involved in the molecular mechanism underlying neurobehavioural impairment in Wistar rats, exposed to noise stress. Single treatment of kaempferol exerted a more potent mitigative effect than zinc gluconate, while their combination produced an improved outcome.

Highlights

Recent years have witnessed a notable increase in the report of noise pollution and its attendant health impacts, especially in metropolitan environments [1,2,3]
The frequency of rearing in groups treated with kaempferol + noise and kaempferol + zinc + noise increased relatively over the noise exposure period, compared to that of the group treated with deionized water + noise
The general pattern of the Kaempferol and zinc gluconate ameliorate noise-induced neurobehavioural impairment frequency of rearing across the treatment groups was that of a progressive decrease throughout the study period (Fig 2A)

Summary

Introduction

Recent years have witnessed a notable increase in the report of noise pollution and its attendant health impacts, especially in metropolitan environments [1,2,3]. Noise stress has been shown to increase the generation of reactive oxygen and nitrogen species which impair lipid and protein molecules, damage DNA, and trigger loss of neuronal function [9]. Sustained exposure to sound levels greater than 85 dB, or sudden exposure to impulse noise lead to irreversible damage of sensory structures including the cochlea [13], and modifies the morphology of astrocytes [14]. Foregoing reports have shown that mice and rats exposed to high-noise intensity respond by freezing into a still stance, while exposure of rats to 95 dB at 0.5–5 kHz for a period of 5 minutes per day for 28 weeks, alters behavior and induces aggression. In open-field behaviour, incessant noise of 85 dB amplifies defecation and decreases social and non-social activities, including sniffing, grooming or crawling of rats, compared with 50 dB, 65 dB or 75 dB [15]

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