protective effects of vitamin E versus vitamin C against cisplatin ototoxicity in guinea pigs [histological and audiological study]

The protective effects of both vitamin E and C against cisplatin induced ototoxicity were assessed histologically and audiogically. This was done by quantifying the extent of cochlear damage with the light microscope, scanning electron microscope and with measurement of the Distortion Product Otoacoustic Emissions [DPOAEs]. Twenty-five adult male guinea pigs were used in this study. They were divided into control group, cisplatin group that was injected 8 mg/kg cisplatin intra-peritoneally [i.p.], vitamin E group that was injected 500 mg/kg of vitamin E i.p.30 mm prior to cisplatin injection, and vitamin C group which was given 200 mg/kg of vitamin C i.p. 30 min before cisplatin administration. When administered alone, cisplatin induced loss and vacuolation of outer hair cells [OHCs] as seen by LM examination. Scanning EM revealed fusion, disarrangement and loss of some stereocilia in the remaining OHCs especially in the basal turn. In contrast, inner hair cells resisted cisplatin ototoxicity. Audiological assessment demonstrated reduction in DPOAEs amplitudes and S/N values in all frequencies. Both vitamin E and C reduced cisplatin ototoxicity, with better protection achieved by vitamin C administration. Scanning EM examination showed that OHCs were similar to the control configuration after vitamin C administration while after protection with vitamin E, OHCs of the third row showed fusion and absorption of the stereocilia in some parts. In addition, both DPOAEs amplitudes and S/N ratio were near the control values up to 4 KHz. However, above 4 KHz both vitamins failed to achieve the full protection, with vitamin C showing better performance in these high frequencies. We conclude that both vitamins had protective effects against cisplatin induced ototoxicity, with vitamin C inducing more protection in the used regimen

Histological changes of the contralateral adrenal cortex following unilateral adrenalectomy in male albino rat

Unilateral adrenalectomy [UA] is performed not only to treat adrenal tumors but also as part of radical nephrectomy. The aim of the present study was to detect the effects of UA on the contralateral adrenal cortex, to identify the primary zone that was affected by adrenalectomy and the time at which the gland was histologically stabilized. Forty adult male albino rats with average weight 150-200 gm were used in this study. The animals were divided into 5 groups. Twelve rats were sham-operated and served as control group [group I]. The remaining 28 rats underwent right UA and were sacrificed after 3 days, 1, 2, 3 weeks [groups II, III, IV, and V respectively]. At the planned times, the left adrenal glands were excised and specimens were prepared for light and electron microscopic studies. Morphometric study was done to measure the thickness and the surface area of the cells of the three classical zones of the adrenal cortex. The results showed frequent mitotic figures in the outer zone of zona fasciculata in group II which was not evident in all other groups. In group III, the thickness and the surface area of the cells of zona fasciculata showed highly significant increase. The cells of zona glomerulosa and fasciculata showed marked cytoplasmic vacuolation more in zona fasciculata. Group IV showed gradual decrease in size and vacuolation of the cells which reverted to near normal in group V; three weeks after UA, denoting stabilization of the adrenal cortex. Electron microscopic examination revealed enlarged mitochondria, dilated smooth endoplasmic reticulum and decreased lipid content in group-III, while near normal appearance was achieved in group V. These results suggested that the compensatory growth in the adrenal cortex following UA was due to both hyperplasia and hypertrophy, and that zona fasciculata is the primary zone responsible for this compensatory growth