Noise In Rats Research Articles

Gender differences in anxiety response to high intensity white noise in rats

Prolong exposure to high intensity white noise (HIWN), defined as a heterogeneous mixture of sound waves extending over a wide frequency range, has detrimental peripheral and central consequences including cardiovascular and emotional effects. Anxiety is a common manifestation of HIWN. Although gender-dependent differences in manifestation of anxiety and/or response to treatment of this condition has been amply documented, potential differences in response to HIWN, a common exposure in combat, construction and rave disco, has not been adequately investigated. In this study, both male and female Wistar rats were subjected to HIWN for 10 consecutive days, 1 h/day. On day 11, a day after the last exposure, the performance of the rats in open field (OF) and elevated plus maze (EPM) was evaluated. Male rats showed a higher anxiety-like response to HIWN as evidenced by: lower number of entries into the open arm of the EPM, lower number of entries into central zone of OF, excess grooming in OF and more boluses in closed arm of EPM. These results indicate that gender-related differences in anxiety in general, and in response to HIWN, in particular, has to be taken into consideration when investigating the neurobiological components and/or treatment modalities.

Behavioral and neuroanatomical effects on exposure to White noise in rats

Noise pollution is a severe public health problem as continuous exposure to even moderate noise levels between 55−65 dB can lead to various pathologies, including neurological states. In the present study, we assessed the ultrastructural alterations in selective auditory pathways of the rat brain following high intensity white noise exposure. In addition, learning, anxiety-like behavior and locomotor activity were assessed. Adult male rats were exposed to 100 dB noise, one hour daily, for 10 consecutive days. The evaluations were performed on day 11. Exposure to noise did not affect learning or the components of locomotor activity. However, it induced anxiety-like behavior as evidenced by time spent in the closed arm of elevated-plus maze. Concomitantly, ultrastructural changes in medial geniculate body, considered an integral component of classical auditory pathway, as well as in the hippocampus and basolateral amygdala, considered important structures of non-classical auditory pathway were noted. Specifically, noise resulted in neuronal apoptosis, chromatolysis, cytoplasmic organelle destruction, and glial activation in medial geniculate body and hippocampus, as well as mild alterations in amygdala. These results provide further evidence of detrimental consequences following exposure to loud noise.

Arecoline cannot alter testicular dysfunction and pineal activation caused by noise in wistar rat

Millions of people consume betel nut for increased capacity to work and for stress reduction. The nut contains arecoline, which has multiple side effects on endocrine functions. Objective of the work is to investigate pineal–testicular responses to noise and after arecoline treatment in noise in rats. Noise exposure (100 dB, 6 h daily, 10 days) caused pineal stimulation ultrastructurally and at indoleamines level. Leydig cell dysfunction with fall of testosterone level and suppression of sex accessories were noticed. In contrast, pineal activity was inhibited and reproductive functions were stimulated after arecoline administration, confirmed from reversed changes to those of noise. Arecoline treatment in noise exposure showed same results as in noise both in pineal and in reproductive functions. It is concluded that noise causes testicular dysfunction probably by gonadotropin suppression induced by pineal melatonin in noise. Furthermore, arecoline cannot prevent it in noise in rats.

Protective effect of Zinc and Salvia on the immune system caused by noise in rats

Objective To observe the protective effect of the zinc gluconate combined with Salvia injection on noise induced serum immunoglobulin(IgG,IgM,IgA) and immune molecules (IL-2,IL-4) in rats.Methods 50 female SD rats were randomly divided into control group,noise group,zinc gluconate noise group(plus zinc group),Salvia injection noise group (plus Salvia group) and Zinc gluconate oral liquid and Salvia injection noise group(combined group),10 rats in each group.Except the control group,rats in the other groups were continuously exposed to high frequency steady noise for two weeks.The concentrations of serum immunoglobulin (IgG,IgM,IgA) and immune molecules (IL-2,IL-4) after the intervention of noise were compared.Results Serum levels of IgG,IgM,IL-2,IL-4of the control group were significantly higher than the noise group (all P ＜ 0.05),plus zinc group (all P ＜ 0.05),plus Salvia group(all P ＜0.05),the differences were statistically significant.Serum level of IgA of each group was not statistically different compared with control group (all P ＞ 0.05).Serum levels of IgG,IgM,IL-2,IL-4 in the noise group were significantly lower than those in the control group (all P ＜ 0.05),combined group (all P ＜ 0.05),the differences were statistically significant.Serum levels of IgG,IgM,IL-2 in plus zinc group were significantly higher than the noise group(all P ＜ 0.05).Serum IgA concentration of each group showed no significant difference compared with noise group(all P ＞ 0.05).Conclusion Zinc gluconate oral solution and Salvia injection have protective effect on immune system affected by noise in rats,the protective effect of combination of zinc gluconate oral solution and Salvia injection is stronger than the individual. Key words: Noise; Zinc gluconate; Salvia injection; Immunoglobulin ; Immune molecules

Myocardial fi brosis in rats exposed to low frequency noise

Low frequency noise (LFN) characterized by large pressure amplitude (≥ 90 dB SPL) and low frequency bands (≤ 500 Hz) can lead to structural and ultrastructural modifi cations in the extracellular matrix of several tissues, with an abnormal proliferation of collagen and development of fi brosis. It is not known whether LFN induces similar structural alterations in the ventricular myocardium of rats.Objective The aim of this study was to evaluate and measure the myocardial fi brosis induced by LFN.Methods Two groups of rats were considered: group A with 26 rats continuously exposed to LFN during a period of 3 months; group B with 20 control rats. The hearts were sectioned from the ventricular apex to the atria and the mid-ventricular fragment was selected. Chromotrope-aniline blue (CAB) staining was used for histological observation. The measurement of fi brosis was performed using the computer image analysis Image J software.Results Histological observation with CAB staining showed the presence of collagen deposition between the cardiomyocytes. Fibrosis increased 97.5%, 81.5% and 83.7%, respectively, in the left ventricle, interventricular septum and right ventricle, in exposed rats (P < 0.001). The ratio fi brosis/muscle in left ventricle, interventricular septum and right ventricle was signifi cantly higher in LFN exposed rats (P < 0.001).Conclusions Our study demonstrates a signifi cant myocardial fi brosis induced by low frequency noise in rats. Our results reinforce the need for further experimental and clinical investigations concerning the eff ects of low frequency noise on the heart.

Effect of Zinc and Salvia on some whole blood metal ion distribution caused by noise in rats

Objective To observe the protective effect of the separate zinc gluconate oral and combined of Salvia injection on whole blood metal ion of calcium,magnesium,iron,copper and zinc concentration in noise-induced rats.Methods 50 female SD rats were randomly divided into a control group,a noise group,a zinc gluconate noise group (plus zinc group),a Salvia injection noise group (plus Salvia group) and a Zinc gluconate oral liquid and Salvia injection noise group (combined group),with10 rats in each group.Except the control group did not expose to noise,the rest groups were continuously exposed to high frequency steady noise for two weeks.Each group was compared for the concentration differences of whole blood metal ion of calcium,magnesium,iron,copper and zinc after the intervention of noise.Results ① In each group at the comparison of the calcium ion concentration: Calcium ion concentration of the control group(1.25± 0.16)mmol/L and the combination group(1.27 ± 0.10) mmol/L was significantly lower than the noise group (1.42 ± 0.18) mmol/L.The rest groups compared to each other were not statistically significant.②Magnesium ion concentration was highest in the noise group (1.53 ± 0.10)rmtmol/L),and lowest in the control group (130 ± 0.29) mmol/L,and the noise group was significantly higher than that of the control group.The mean of magnesium ion concentration in plus zinc group (1.42± 0.27) mmol/L,plus Salvia group (1.38± 0.15) mmol/L and combined group(l.37±0.11)mmol/L were lower than the noise group,but the difference was not significant (P＞0.05).③ The iron ion concentration of the noise group (5.47± 1.29)mmol/L was significantly lower than the other four groups (P＜0.05).The control group,plus zinc group,plus Salvia group,the combined group showed no significant differences.④ Whole blood copper ion concentration of the noise group (16.69 ± 4.18) μmol/L was significantly lower than the control group (21.53 ± 3.78) μmol/L and the combination group(19.53± 1.92)μmol/L with a statistical difference; compared with the control group,the concentration of copper ions in plus zinc group(16.19± 1.93)mμol/L was significantly lower (P＜0.05).⑤The whole blood zinc ion concentration in the noise group (50.83±7.99)μmol/L was significantly lower than the other groups,zinc ion concentration in the plus Salvia group (53.87±6.77)μmol/L was significantly lower than the control group (63.86± 8.83) μmol/L; the whole blood zinc ion concentration showed no difference between the plus zinc group (54.81 ± 5.90) μmol/L,plus Salvia group and combined group (59.21 ± 3.90) μmol/L.Conclusion Combined zinc gluconate oral solution and Salvia injection had protective effect on whole blood metal ion concentration affected by noise.The protection effect of zinc gluconate oral solution and Salvia injection combination was stronger than any individual. Key words: Zinc gluconate oral solution; Salvia Injection; Noise; Metal ion

Lipoic acid and 6-formylpterin reduce potentiation of noise-induced hearing loss by carbon monoxide: Preliminary investigation

Potentiation of noise-induced hearing loss (NIHL) by specific chemical contaminants and therapeutic drugs represents a distinct public health risk. Prediction of chemicals that yield such potentiation has not been successful because such agents differ markedly in structure. One mechanism for this potentiation that has garnered support is oxidative injury to the cochlea. Thus far, limited data have been published in support of this hypothesis. The current experiment was designed to further test this model using two antioxidant compounds, lipoic acid (LA) and 6-formylpterin (6-FP), and determine whether they would block potentiation of NIHL resulting from simultaneous exposures to carbon monoxide (CO) and noise in rats. Neither CO nor noise exposure at the intensity and duration selected produce persistent auditory impairment by themselves. Different groups of rats were exposed to noise alone centered at 8.0 kHz (105 dB) for 2 hours or to combined CO + noise treatment consisting of CO exposure for 1.5 hours and then exposure to CO + noise for 2 hours. Additional groups received either LA (100 mg/kg) or 6-FP (14 mg/kg) 30 minutes prior to the onset of CO + noise. Cochlear function was monitored using distortion product otoacoustic emissions, and auditory thresholds were assessed using compound action potentials recorded from the round window. Histopathological evaluation of the organ of Corti provided counts of missing hair cells in each treatment group. The CO + noise-exposure group replicated previous studies in demonstrating permanent impairment of cochlear function and associated outer hair cell loss that greatly exceeded the minimal losses observed in the group treated with noise alone. Both LA and 6-FP given 30 minutes prior to the onset of CO + noise exposure reduced cochlear impairment and loss of hair cells.

Hazards to Hearing from Combined Exposure to Toluene and Noise in Rats

The main risk of hearing impairment from workplace exposure to organic solvents may stem from the potentiation of effects caused by concomitant noise exposure. The aim of the present study was to identify the main hazards from combined long-term, low-level exposure to noise and aromatic organic solvents, like toluene, in rats. The rats were exposed to steady-state, wide-band noise (WBN) and 0 ppm, 100 ppm, 200 ppm and 500 ppm toluene for 90 days. Hearing was assessed using Auditory Brain Stem Responses (ABR) and Distortion Product Oto-Acoustic Emissions (DPOAE) eight weeks after exposure. The impact of noise composition on the interaction between solvent and noise exposure was investigated in rats exposed for 10 days either to 0 ppm, 500 ppm, 1000 ppm or 1500 ppm toluene and either WBN or impulse noise. ABR and DPOAE tests were performed before and two weeks after exposure. Long-term exposure of rats to WBN and toluene at 500 ppm or less did not show any increase in hearing impairment, compared to the rats exposed to noise only. Synergistic interaction was demonstrated in short-term exposure to 1500 ppm toluene and both to WBN and impulse noise, but hearing impairment was much larger when following exposure to impulse noise. In combined exposure to low-levels of noise and toluene, even a long-term exposure did not reveal a potential hazard of hearing impairment. Synergistic interaction in combined short-term exposure to toluene and noise was noted both with respect to WBN and impulse noise, but the impulse noise was much more disruptive than WBN at the same level of noise exposure. The ototoxicity of organic solvents may primarily be a hazard also to human hearing due to the exacerbation of hearing loss by a possible co-exposure to especially harmful noise, such as impulse noise.

Effects of toluene exposure on blood pressure and its responsiveness to impulse noise in rats

Effects of a single exposure to toluene at a concentration of 1000 ppm for 4 h on rats' systolic blood pressure were investigated. 9 rats were used in each group (control and exposed groups). The basic blood pressure of the exposed group was significantly lower than that of the control group. The movement of systolic blood pressure due to impulse noise exposure was significantly smaller in the exposed group than in the control group. Toluene exposure at concentration of 1000 ppm for 4 h produced narcotic and inhibitory actions in the diencephalohypophysial and the adrenal gland system in rats.

8th nerve round window action potentials masked by high frequency noise in rats and guinea pigs: a comparative study.

AbstractTheoretical and experimental evidence supports the hypothesis that the VIIIth nerve action potential is a precise summation of individual neuron responses. Based on this concept, the action potential, as measured at the round window was altered in a predictably reproducible manner, by the addition of narrow frequency bands of masking noise. Rat and guinea pig cochleas were studied by means of an analytic method described by Teas, Eldredge and Davis. The latency and amplitude of the VIIIth nerve action potential were compared by analysis of variants for variable stimulus intensity and noise band frequency; in addition, interspecies variability was characterized. Results are discussed in light of known anatomic and behavioral data. Applications to human electrocochleography are discussed.