AIMTo explore the effects of gentamicin ototoxicity on the expression of heat shock protein 70 in guinea pigs cochlea.

METHODSWe used immunohistochemistry staining and image quantitative analysis system, combined with auditory brainstem response (ABR) measurement to investigate the change on the expression of HSP70 in guinea pigs cochlea of gentamicin ototoxicity.

RESULTSThe levels of HSP70 immunoreactivity in guinea pigs cochlea of experimental animals were high including Corti's organ, stria vascularis, medial spiral limbus, spiral ganglion cells and the threshold of ABR was in high correlation with the expression of HSP70 ([ r] > 0.8, P < 0.01).

CONCLUSIONGentamicin can induce expression of HSP 70 in guinea pigs cochlea and protect hearing function.

Animals ; Cochlea ; drug effects ; physiopathology ; Gentamicins ; toxicity ; Guinea Pigs ; HSP70 Heat-Shock Proteins ; metabolism ; Heat-Shock Response ; drug effects

Nephrotoxicity is a major limiting factor in the use of aminoglycoside antibiotics, the mechanisms for which are still speculative. To clarify the mechanisms of renal tubular cell death induced by aminoglycosides, we examined the renal proximal tubule-like cell line, LLC-PK1, after inducing apoptosis through a chronic treatment with gentamicin (GM). Changes in the expression of the Fas were also investigated. On flow cytometric analysis, 5.7 +/- 3.3% of the control cells appeared in a region of decreased forward light scatter and increased side light scatter, where both indices represent the characteristics of apoptotic cell death. Compared to the control, treatment with 10 mM of GM for 15 days significantly increased the proportion of cells in the apoptotic region to 23.9 +/- 8.5%. This finding was supported by electrophoretic analysis of the DNA extracted from the GM-treated cells, where a series of bands corresponding to integer multiples of 180 to 200 base pairs was visualized. However, the 15-day GM treatment did not cause a significant elevation in the expression of the 45 kD Fas protein, the cell surface molecule that stimulates apoptosis, by Western blot analysis. In conclusion, long-term exposure to GM induces apoptosis of the renal tubular epithelial cells, and this process may contribute to some of the aminoglycoside nephrotoxicities. Further studies are needed on the mechanism(s) of apoptosis induced by GM.
Animal ; Antibiotics, Aminoglycoside/toxicity* ; Antigens, CD95/analysis ; Apoptosis/drug effects* ; Cell Line ; Gentamicins/toxicity* ; Kidney Tubules, Proximal/pathology ; Kidney Tubules, Proximal/drug effects* ; Swine

OBJECTIVETo investigate uptake and accumulation of gentamicin by cells in the guinea pig inner ear after intratympanic injection using a fluorescent probe--gentamicin-Texas-red conjunction (GTTR).

METHODSAdult guinea pigs (n = 80) were administered a single dose of GTrR to the middle ear cavity through the intact membrane and survived for 12 h, 24 h, 48 h, 3 d, 4 d, 7 d, 14 d and 28 d. The distribution of GTTR in the cochlear and vestibular cells was observed after staining with phalloidin-alexa-488. Texas Red and DMSO were injected into the tympanum as control.

RESULTSDiffuse staining of gentamicin in the labyrinth was observed initially after local drug administration. At later time point the outer hair cells and sensory cells of vestibular organ were staining more densely than the support cells in the inner ear. The peak level of fluorescent density was reached 3 days after local injection. The GTTR was observed in the infracuticular zone.

CONCLUSIONSGTTR was a potential fluorescent probe to investigate the pharmacokinetics and mechanisms of gentamicin accumulation in local application.

Animals ; Anti-Bacterial Agents ; administration & dosage ; pharmacokinetics ; toxicity ; Ear, Inner ; metabolism ; Fluorescent Dyes ; Gentamicins ; administration & dosage ; pharmacokinetics ; toxicity ; Guinea Pigs ; Hair Cells, Auditory ; metabolism

OBJECTIVETo explore an effective method for treating Gentamicin-induced deafness and the mechanism.

METHODSGuinea pigs were randomly divided into 5 groups: normal control group (group A), model group (group B), Ligustrazine group (group C), acupuncture group (group D) and Ligustrazine plus acupuncture group (group E). The group C, D and E were treated respectively by simple Ligustrazine, simple acupuncture at "Tinggong" (SI 19), "Yifeng" (TE 17), and "Waiguan" (TE 5), and Ligustrazine plus acupuncture. Ten days later, the auditory brainstem response (ABR) thresholds for the wave III , apoptosis and expressions of Bcl-2 and Bax proteins in the organ of Corti of the guinea pig were detected.

RESULTSIn the group E, the ABR threshold was significantly lower than that in the group C (P<0.05), and apoptotic cells, the expression of Bax protein and the ratio of Bax/Bcl-2 were lower than those in the group C and D in the organ of Corti, and Bcl-2 protein expression was increased.

CONCLUSIONAcupuncture at "Tinggong" (SI 19), "Yifeng" (TE 17), and "Waiguan" (TE 5) has a certain target-synergistic action on Ligustrazine and can increase therapeutic effect of Ligustrazine on Gentamicin-induced deafness, which are possible related with the inhibition of apoptosis, down-regulation of Bax expression and up-regulation of Bcl-2 expression.

Acupuncture Therapy ; Animals ; Anti-Bacterial Agents ; toxicity ; Deafness ; chemically induced ; therapy ; Evoked Potentials, Auditory, Brain Stem ; drug effects ; Female ; Gentamicins ; toxicity ; Guinea Pigs ; Male ; Pyrazines ; therapeutic use

We investigated the effect of urinary alkalinization accomplished by intraperitoneal injection of sodium bicarbonate and acetazolamide on gentamicin nephrotoxicity in male Fisher 344rats. Forty rats (body weight 200-300g) were divided into four groups: control (gentamicin 20mg/kg, bid), high sodium load (gentamicin 20mg/kg, 25cc of saline, bid), low bicarbonate (gentamicin 20mg/kg, 25cc of sodium bicarbonate 100mEq/L, 2.5mg of Diamox, bid) and high bicarbonate (gentamicin 20mg/kg, 10cc of sodium bicarbonate 250mEq/L, 2.5mg of Diamox, bid) groups. All drugs and electrolyte solutions as mentioned above were administered intraperitoneally twice a day for seven days and changes in renal functions were studied. While salt loading failed to influence the severity of gentamicin nephrotoxicity, urinary alkalinization induced by bicarbonate and acetazolamide injection showed remarkable ameliorating effects on gentamicin nephrotoxicity. The high bicarbonate group exhibited more beneficial effects than the low bicarbonate group on gentamicin nephrotoxicity. So, urinary alkalinization seems to be an effective method for the prevention of gentamicin nephrotoxicity in rats.
Animal ; Bicarbonates/*administration and dosage ; Carbon Dioxide/urine ; Gentamicins/*toxicity ; Kidney Diseases/chemically induced/*prevention and control ; Male ; Random Allocation ; Rats ; Rats, Inbred F344

To examine the significance of heat shock protein 70 mRNA in ototoxicity resulted from gentamicin (GM), twenty healthy albino guinea pigs (200-250 g) of either sex with a positive Prier reflex were divided into two groups randomly. In GM group the animals received 100 mg/kg GM daily by intraperitoneal injection for 10 d. In saline control group the animals received 2.5 ml/kg saline daily by intraperitoneal injection for 10 d. Auditory brainstem response (ABR) thresholds were recorded in each animal before and 1 d after GM or saline administration. After the second ABR measurement, the expression of HSP70 mRNA in guinea pig cochlea was observed with in situ hybridization and image quantitative analysis system. The results showed that the threshold of ABR in the GM group was significantly higher than that of the saline control (P< 0.001). The expression of HSP70 mRNA was more intensive in stria vascularis, spiral ligament and spiral ganglion cells in the GM group than that of the saline control group. These results suggest that administration of gentamicin can induce the expression of HSP 70 mRNA in guinea pig cochlea, and that this effect may protect hearing function from ototoxicity.
Animals ; Cochlea ; metabolism ; Evoked Potentials, Auditory, Brain Stem ; physiology ; Female ; Gentamicins ; toxicity ; Guinea Pigs ; HSP70 Heat-Shock Proteins ; biosynthesis ; genetics ; Male ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation

AIMTo investigate the preventive effects of the cerebro cellular growth peptide (CCGP) on gentamycin-induced inner ear damage in guinea pigs, and to clarify its mechanism.

METHODSThe hypoacusis severity and enzymatic activity in the cochlear hair cells were examined by brainstem auditory evoked potential (BAEP) and histochemistry, respectively. The damaged hair cells was counted in three groups.

RESULTSCCGP reduced the elevated BAEP reaction thresholds. It protected activities of mitochondrial succinate dehydrogenase and lysosome acid phosphatase in the cochlear hair cells. The number of damaged hair cells in the CCGP group was less than that in the gentamycin (GM) group.

CONCLUSIONCCGP can reduce GM ototoxicity. The mechanism may be associated with the protective activity of mitochondrial enzyme, the maintenance of lysosome intactness, energy metabolism of the cochlear hair cells, and reduction of autolysis of hair cells induced by hydrolase over flowing from lysosome.

Animals ; Evoked Potentials, Auditory, Brain Stem ; Female ; Gentamicins ; toxicity ; Guinea Pigs ; Hair Cells, Auditory ; drug effects ; physiology ; Male ; Nerve Growth Factor ; pharmacology

AIMTo study the antagonistic action of acanthopanax senticosus injection (ASS) on gentamicin ototoxicity.

METHODSGuinea pigs were randomly divided into control group, GM group, ASS group, and ASS + GM group. The changes of hearing threshold, cochlear morphology, expression of caspases-3 were determined by ABR, TEM, and Western blot, respectively.

RESULTSThe ABR threshold in GM group increased markedly. There was no significant difference in ABR threshold between ASS group and control group, but the ABR threshold in ASS group was much lower than that both in GM group and ASS + GM group. Severely injured hair cells with morphological characteristics of apoptosis were found under TEM in GM group, and the hair cells were less injured in ASS + GM group. The results of Western blot showed that the expression of caspase-3 increased markedly in GM group, but it increased slightly in ASS + GM group.

CONCLUSIONASS may antagonize the GM ototoxicity by inhibiting the expression of caspases-3.

Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Eleutherococcus ; Gentamicins ; toxicity ; Guinea Pigs ; Hair Cells, Auditory ; cytology ; drug effects ; Plant Extracts ; pharmacology

AIMTo investigate the effects of injectio Salvia Miltiorrhiza (SM) on gentamicin (GM)-induced free radical formation in guinea pig cochlea, and to explore possible mechanisms on GM-induced ototoxicity.

METHODSBiochemical assays of superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in guinea pig cochlea, combined with auditory brainstem response (ABR) measurement and transmission electron microscopic observation were used in this investigation.

RESULTSSOD activity was significantly declined while MDA content was distinctly increased in cochlear tissues after GM injection (P < 0.01). Moreover, they were well correlated with auditory function damage (|r| > 0.7). Co-treatment with SM evidently enhanced SOD activity and decreased MDA content (P < 0.01, P < 0.05). Furthermore, auditory function was markedly ameliorated. Morphological changes of cochlea were consistent with those of hearing function.

CONCLUSIONLipid peroxidation elicited by free radical was involved in GM-induced cochleotoxicity. SM might enhance SOD activity and prevent lipid peroxidation. As the result it might alleviate GM ototoxicity, and improve auditory function.

Animals ; Cochlea ; drug effects ; metabolism ; Free Radicals ; metabolism ; Gentamicins ; toxicity ; Guinea Pigs ; Lipid Peroxidation ; Malondialdehyde ; analysis ; Salvia miltiorrhiza ; Superoxide Dismutase ; metabolism

OBJECTIVETo explore the effect of acupuncture at "Neitinggong" drug-induced deafness.

METHODSGuinea pig deafness model was prepared by injection of gentamicin (GM). Acupuncture was respectively given at the points "Neitinggong" "Tinggong" (SI 19) and non-acupoints on the auricle in the experimental animals in different groups and the effects of different points on the auditory brainstem response and cochlear hair cells were observed.

RESULTSThere was a significant difference between GM group and Neitinggong group, and between GM group and Tinggong group. There was no significant difference between GM group and the auricle group, and between Neitinggong group and Tinggong group.

CONCLUSIONAcupuncture at "Neitinggong" can strength the function of the internal ear, and relieve the injury of cochlear hair cells caused by gentamicin, which is an effective acupoint for treatment of drug-induced deafness.

Acupuncture Points ; Acupuncture Therapy ; Animals ; Anti-Bacterial Agents ; toxicity ; Cochlea ; drug effects ; pathology ; Deafness ; chemically induced ; prevention & control ; Evoked Potentials, Auditory, Brain Stem ; drug effects ; Female ; Gentamicins ; toxicity ; Guinea Pigs ; Hair Cells, Auditory ; drug effects ; pathology ; Male