Effects of ototoxic antibiotics on gastric secretion and gastric mucosa in rats
Streptomycin was the first clinically effective drug to become available for the
treatment of tuberculosis but many investigators reported labyrinthine and
vestibular dysfunction including vertigo, tinnitus, ataxia and hearing loss in the
course of tuberculosis therapy with this drug.
Thereafter the other aminoglycosides such as neomycin, kanamycin and gentamicin,
and also polypeptides of this series, viomycin and capreomycin, were introduced.
Nevertheless, all of these drugs showed some degree of similar ototoxicity as it
seen in streptomycin. Studies on histopathological changes of inner ear revealed
that these antibiotics produced degeneration of internal and external hair cells,
and spiral ganglion cell in Corti's organ as well as changes of endolymph pressure
in scala media.
Moon (1971) reported the circular movement caused a decrease in gastric secretion
but failed to decrease after labyrinthectomy or streptomycin treatment. Schapiro et
al (1970, 1971) reported visual deprivation or labyrinthectomy caused a marked
depression of gastric secretion and concluded that this might result from reduced
gastric vagal activity and therefore the parietal cells and the chief cells became
Present study was undertaken to observe the effect of various ototoxic
antibiotics on the gastric secretory activity and gastric mucosa.
One hundred and fifty albino rats of both sexes weighing 200 gm around were
divided into two experimental groups.
Experiment 1: The following antibiotics, diluted into 10 ml of saline, was
injected i.p. 30 minutes prior to procedure: Streptomycin 400 mg/kg, neomycin 200
mg/kg, gentamicin 5 mg/kg or viomycin 100 mg/kg. Control animals were administered
either with saline (10 ml/kg) or penicillin(800,000 lU/kg). After ligation of
pylorus (Shay operation of the rat) gastric juice was collected for 6 hours.
Experiment 2 : The following antibiotics was injected daily for 1 week after same
preparation as experiment 1 : Streptomycin 200 mg/kg, neomycin 100 mg/kg,
gentamicin 2.5 mg/kg, capreomycin 200 mg/kg, or viomycin 50 mg/kg. After treatment
the pylorus of the stomach was ligated for 20 hours.
Acidity of gastric juice was determined by consumed amount of NaOH (mEq/L) by
means of Titrator TTT 2b with the end point of pH 3 and pH 8 on free acidity and
total acidity, respectively.
Gastric mucosal changes were observed with stereoscope.
The results obtained are summarized as follows :
1. Gastric secretion was significantly inhibited by the treatment with ototoxic
antibiotics, especially with neomycin and capreomycin. However with gentamicin the
gastric secretion was enhanced.
2. The pH of gastric juice was markedly increased in all groups especially in
neomycin and carpreomycin treated group.
3. The concentration of gastric acid was generally decreased, moreover, the free
acid in capreomycin treated group was only trace amount.
4. The mucosal changes of the stomach after one week treatment with ototoxic
antibiotics were seen on foregut only. The most severe mucosal damage was seen in
gentamicin and kanamycin groups but little damage in capreomycin group.
By these findings it may be suggested that the ototoxic antibiotics affect the
gastric secretion and gastric mucosa greatly and that the more toxic to the ear,
the less amount of gastric secretion and the less damage to the gastric mucosa.