Evaluation of the protective effect of Beta glucan on amikacin ototoxicity using distortion product otoacoustic emission measurements in rats

Efficacy of levocetirizine in isolated rat tracheal smooth muscle

Histamine receptor-1 (H1) antagonists like levocetirizine are frequently used nowadays to treat rhinitis patients who experience rhinorrhea and sneezing. The trachea may be affected by the H1 antagonist when it is used to treat nasal symptoms, either orally or through inhalation. The purpose of this study was to ascertain in vitro effects of levocetirizine on isolated tracheal smooth muscle. As a parasympathetic mimetic, methacholine (10-6 M) causes contractions in tracheal smooth muscle, which is how we tested effectiveness of levocetirizine on isolated rat tracheal smooth muscle. We also tested the drug's impact on electrically induced tracheal smooth muscle contractions. The impact of menthol (either before or after) on the contraction brought on by 10-6 M methacholine was also investigated. According to the results, the addition of levocetirizine at concentrations of 10-5 M or more caused a slight relaxation in response to methacholine's 10-6 M contraction. Levocetirizine could prevent spike contraction brought on by electrical field stimulation (EFS). As the concentration rose, it alone had a neglect effect on the trachea's basal tension. Before menthol was applied, levocetirizine might have also inhibited the function of the cold receptor. According to this study, levocetirizine might potentially impede the parasympathetic function of the trachea. If levocetirizine was used prior to menthol addition, it also reduced the function of cold receptors.

Experimental animal models of drug-induced sensorineural hearing loss: a narrative review

Objective

This narrative review describes experimental animal models of sensorineural hearing loss (SNHL) caused by ototoxic agents.

Background

SNHL primarily results from damage to the sensory organ within the inner ear or the vestibulocochlear nerve (cranial nerve VIII). The main etiology of SNHL includes genetic diseases, presbycusis, ototoxic agents, infection, and noise exposure. Animal models with functional and anatomic damage to the sensory organ within the inner ear or the vestibulocochlear nerve mimicking the damage seen in humans are employed to explore the mechanism and potential treatment of SNHL. These animal models of SNHL are commonly established using ototoxic agents.

Methods

A literature search of PubMed, Embase, and Web of Science was performed for research articles on hearing loss and ototoxic agents in animal models of hearing loss.

Conclusions

Common ototoxic medications such as aminoglycoside antibiotics (AABs) and platinum antitumor drugs are extensively used to induce SNHL in experimental animals. The effect of ototoxic agents in vivo is influenced by the chemical mechanisms of the ototoxic agents, the species of animal, routes of administration of the ototoxic agents, and the dosage of ototoxic agents. Animal models of drug-induced SNHL contribute to understanding the hearing mechanism and reveal the function of different parts of the auditory system in humans.

Protective effect of creatine on amikacin-induced ototoxicity

Introduction

Aminoglycosides are widely known for their ototoxic side effects. Nevertheless, they are potent antibiotics used in the treatment of life-threatening conditions because of the current concern for antibiotic resistance. We hypothesized that creatine supplements which are believed to improve mitochondrial antioxidant defense system and maintain optimal energy homeostasis may improve the ototoxic side effects.

Objective

This study aimed to investigate the protective effects of creatine monohydrate against ototoxicity induced by amikacin in rats in an experimental animal model, using distortion product otoacoustic emissions and auditory brainstem response.

Methods

Twenty healthy rats were assigned to four groups (5 rats in each): the control group, the creatine monohydrate group, the amikacin group and the amikacin + creatine monohydrate group. The creatine monohydrate group received creatine at a dose of 2 g/kg once daily via gastric gavage for 21 days. The amikacin group received amikacin at a dose of 600 mg/kg by intramuscular injections once daily for 21 days. The amikacin + creatine monohydrate group received intramuscular injections of amikacin (600 mg/kg) once daily for 21 days and creatine monohydrate (2 g/kg) once daily via gastric gavage for 21 days. The control group received nothing. The distortion product otoacoustic emissions and auditory brainstem response measurements were performed on all rats on days 0, 7, 21.

Results

Regarding auditory brainstem response values, a significant increase in the auditory threshold was observed in the amikacin group on day 21 (p <  0.001). The amikacin+creatine monohydrate group showed significantly lower levels of auditory brainstem response auditory thresholds on day 21 in comparison to the amikacin group (p <  0.001). Additionally, the control group and the amikacin+creatine monohydrate group did not differ significantly with respect to auditory brainstem response thresholds on treatment day 21 (p >  0.05). When we compare distortion product otoacoustic emissions values, there was no significant difference between the amikacin and amikacin+creatine monohydrate groups on day 7 (p >  0.05), However significantly greater distortion product otoacoustic emissions values were observed in the amikacin+creatine monohydrate group on day 21 compared to the amikacin group (p <  0.001).

Conclusion

Our findings demonstrate that creatine treatment protects against amikacin ototoxicity when given at a sufficient dose and for an adequate time period.

Protective effect of pentoxifylline on amikacin-induced ototoxicity

We conducted an animal experiment to assess the effect of adding pentoxifylline to amikacin to prevent amikacin-induced ototoxicity. This research was conducted on 24 rats arranged in four groups of 6. One group was injected with 200 mg/kg of intramuscular amikacin once daily for 14 days (AMK-only group). Another received 25 mg/kg of oral pentoxifylline and 200 mg/kg of intramuscular amikacin once daily for 14 days (PTX-AMK 14/14 group). A third group received 25 mg/kg of oral pentoxifylline for 28 days and 200 mg/kg of intramuscular amikacin once daily for 14 days on days 15 through 28 of the pentoxifylline regimen (PTX-AMK 28/14 group). Finally, a control group was administered 1 ml/day of 0.5% carboxymethyl cellulose for 28 days. Transient otoacoustic emissions (TOAEs) were statistically analyzed and serum urea and creatinine levels were measured before and after treatment. We found no significant differences in TOAEs among the groups at the study's onset, but after the experiment, TOAEs disappeared in all frequency bands in the AMK-only and PTX-AMK 14/14 groups. However, TOAEs were preserved in the PTX-AMK 28/14 group. In addition, the serum urea and creatinine levels in the PTX/AMK 28/14 group were significantly lower than the levels in the other two treatment groups (p < 0.05 for all), but not significantly different from those of the control group. We conclude, therefore, that 28 days of pentoxifylline treatment exerted a protective effect against amikacin-induced ototoxicity in rats.

Evaluation of auditory and cochlear functions in ankylosing spondylitis patients according to the site of involvement

Ankylosing spondylitis (AS) is a chronic systemic inflammatory disease of unknown origin with a prevalence rate about 1% in the population. Audiovestibular dysfunction is encountered in AS and sensorineural hearing loss is the most common form. The present study aimed to evaluate auditory and cochlear function in AS patients according to the site of involvement. A total of 47 patients followed for AS in the rheumatology outpatient clinic and 30 healthy controls were enrolled in the study. Subgroups of AS were identified according to the site of involvement. The participants underwent complete otolaryngological examination together with audiometry, otoacoustic emission and tympanometry tests. Disease Activity Index (BASDAI) was determined in the AS group. Hearing loss was detected in seven patients (15%) in the AS group and in four subjects (8%) in the control group. There was statistically significant difference between the patient and control groups in terms of mean bone conduction hearing level at 4000 hertz (Hz) in the right and left ears (p = 0.028, p = 0.049). There was no significant difference between the subgroups of AS in terms of overall auditory and cochlear functions. No correlation was determined between auditory values and Disease Activity Index and CRP (p > 0.05 for all). Our results reveal that AS has minimal effect on auditory and cochlear functions. The effects of subgroups of AS on auditory functions were comparable. The authors concluded that BASDAI and CRP are not convenient in monitoring auditory functions of AS patients.

An Evaluation of the Protective Effects of Thymoquinone on Amikacin-Induced Ototoxicity in Rats

Objectives

In this study we investigated the probable protective effects of thymoquinone on amikacin-induced ototoxicity in rats.

Methods

Thirty-two healthy rats were divided into four groups (amikacin, amikacin+thymoquinone, thymoquinone, and no treatment). Thymoquinone was fed to the rats via oral gavage in a dose of 40 mg/kg/day throughout the study period of 14 days. Amikacin was given by the intramuscular route in a dose of 600 mg/kg/day. Audiological assessment was conducted by the distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) tests, administered to all rats at the beginning of the study, and also on days 7 and 15. Biochemical parameters were calculated at the termination of the study to evaluate the oxidative status.

Results

There were significant decreases in DPOAE values and significant increases in ABR thresholds of the amikacin group on days 7 and 15, as compared to the amikacin+thymoquinone group. While ABR thresholds of the amikacin group increased significantly on days 7 and 15 as compared to their initial values, there were no significant differences between the initial and the 7th and 15th day values of ABR thresholds in the amikacin+thymoquinone group. Total oxidant status and oxidative stress index values of the amikacin+thymoquinone group were significantly lower than those of the amikacin group. Total antioxidant status values of the amikacin+thymoquinone group were significantly higher than those of the amikacin group.

Conclusion

Our study has demonstrated that the ototoxic effect brought forth by amikacin could be overcome with the concurrent use of thymoquinone.

Evaluation of Hearing and Outer Hair Cell Function of Cochlea in Patients With Psoriatic Arthritis

Objectives

The aim of this study was to investigate hearing and outer cells function in patients with psoriatic arthritis. Our investigation was a prospective case control study.

Methods

A total of 31 psoriatic arthritis patients (62 ears) and 31 healthy control subjects (62 ears) were enrolled in the study. We investigated hearing changes of patients and controls via pure tone audiometry, speech discrimination scores, tympanometry, acoustic reflex, and transient product otoacoustic emission.

Results

The mean age of psoriatic arthritis patients was 36.1±8.5 years (range, 14 to 62 years). The average age of the control group was 37.9±8.1 years (range, 16 to 62 years). There were statistically significant differences between pure tone audiometry in all frequencies and right and left emission at the 4.0 and 1.0 in psoriatic arthritis patients versus controls (P<0.05). This difference was evident, especially at high frequencies. There was no statistically significant difference between the ages and genders of the patient and control groups (P>0.05). Both audiological and otoacoustic emissions were not significantly different between right and left ear (P>0.05).

Conclusion

Based on the audiological and otoacoustic findings; it is likely that the cochlear outer hair cells become subtly damaged in psoriatic arthritis patients, consequently leading to changes in hearing thresholds. These data suggest that it is important to screen psoriatic arthritis patients for hearing changes with otoacoustic emissions and audiologic tests regularly.

Betahistine exacerbates amikacin ototoxicity

OBJECTIVE

Betahistine augments cochlear blood flow and is currently used as an efficient therapeutic agent. Amikacin is used in a wide range of areas, but its ototoxic effect continues to be problematic. This study investigates the effect of betahistine on amikacin-induced ototoxicity.

METHODS

Thirty-two healthy rats were randomized to 4 groups of 8 rats in each group (amikacin, amikacin+betahistine, betahistine, and no treatment). Amikacin was administered intramuscularly to groups 1 and 2 for 14 days. Betahistine was delivered by oral gavage to groups 2 and 3 for 21 days. Distortion-product otoacoustic emissions (DPOAE) and auditory brainstem response (ABR) tests were conducted on all rats.

RESULTS

There were significant decreases in the DPOAE levels and significant increases in the ABR thresholds of the amikacin and amikacin+betahistine groups on the 7th, 14th, and 21st days, as compared to their basal values. The DPOAE levels of the amikacin+betahistine group significantly decreased on days 7, 14, and 21, and the ABR thresholds significantly increased on the same days, as compared to the amikacin group.

CONCLUSION

Our study implies that amikacin's ototoxic effects are augmented by the concurrent use of betahistine. Experimental and clinical research, supported by histopathological studies, is needed to affirm our findings.

Protective effect of trimetazidine on amikacin-induced ototoxicity in rats

OBJECTIVE

Aminoglycoside antibiotics are known to have ototoxic effects and may induce sensorineural hearing loss. This study investigated the protective effect of trimetazidine, which has antioxidant and cytoprotective properties, against amikacin ototoxicity.

METHODS

Thirty-two male rats were divided into four groups - amikacin, amikacin + trimetazidine, trimetazidine, and control groups. Trimetazidine, 10 mg/kg per day, was given for 14 days by oral gavage. Amikacin, 600 mg/kg per day, was also given for 14 days, by the intramuscular route. Distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) tests were applied to the rats for hearing assessment. At the termination of the study, the biochemical parameters were calculated to evaluate the oxidative status.

RESULTS

The DPOAE values of the amikacin group were significantly lower on the 7th and 14th days than those of the trimetazidine + amikacin group and there was an increase in the ABR thresholds. The ABR thresholds for the amikacin group on the 7th and 14th days were significantly higher than the levels on the first day of the study, while there was no significant increase in those values in the trimetazidine + amikacin group. The total oxidant status (TOS) and oxidant status index (OSI) values of the amikacin group were significantly higher than those of the trimetazidine + amikacin group. The total antioxidant status (TAS) values of the amikacin group were lower than those of the trimetazidine + amikacin group.

CONCLUSIONS

The audiologic tests and biochemical parameters investigated in this study both point to the protective effect of trimetazidine against amikacin-induced ototoxicity.

Effects of β-glucan on some environmental toxins: An overview

BACKGROUND

Beta-glucans are naturally occurring polysaccharides and constituents of the cell wall of certain pathogenic bacteria and fungi. They have proven healing and immunostimulating properties, linked to enhanced macrophage and natural killer cell function which likely involves specific interaction with several cell surface receptors, such as lactosylceramide, selected scavenger receptors, and dectin-1 (betaGR). In particular, glucan reduces the immunosuppressive effects of a number of agents including chemo therapy and radiation. More recent studies suggest a positive function for glucan in the immunosuppression caused by toxic agents in the environment.

AIM

An overview of the effects of glucan on the mycotoxin, aflotoxin and other environmental toxins (mercury-thimerosal, depleted uranium).

CONCLUSION

Glucan is effective as a natural immunomodulator and could be used as an inexpensive solution to reducing the adverse effects of some environmental toxins.

The effect of Beta glucan on Cisplatin ototoxicity

This study was undertaken to investigate the effect of betaglucan in ameliorating cisplatin ototoxicity. Rats were divided into four groups: cisplatin (C), cisplatin plus beta glucan (CB), beta glucan (B), and control (K). Distortion product otoacoustic emissions were elicited in 0th, 1st, and 5th days. For the group C differences were observed at 8,003 and 9,515 Hz between 0th and 5th days' measurements. In the group CB there were differences at frequencies of 3,996, 4,757, 5,660, and 6,726 Hz between 0th and 5th days' measurements. For the group B there were significant recovery in some frequencies. The observation of significant deterioration in terms of hearing in the group treated with cisplatin plus betaglucan may be suggested that depended on the increase of permeability and tissue conductance into the inner ear which may be caused by betaglucan. Further long-term follow-up studies by using different doses may clarify this matter.