Effects of Sodium Salicylate on Auditory Cortex of Adult Albino Rats and Possible Recovery after Its Withdrawal: Comprehensive Cytoarchitectural, Ultrastructural, Immunohistochemical and Morphometric Investigations

Objective: Sodium salicylate (SS) is frequently used in clinics to treat inflammation, headaches, and fevers. It has antiviral, anticancer, and antidiabetic effects, in addition to their analgesic and antipyretic properties. The present study was designed to throw a light on the effect of SS on the adult auditory cortex in the albino rat and to detect the possibility of recovery following its withdrawal through a comprehensive cytoarchitectural, ultrastructural, immunohistochemical and morphometric investigations. Methods: A total of 45 three-month-old male Albino rats were used in the present work. The animals were divided into 3 groups (each group consisted of 15 rats): control group received saline twice daily for 14 days, salicylate group received SS 200 mg/kg twice daily for 14 consecutive days and salicylate withdrawal group received SS at the same dose and period like salicylate group then accompanied with 14 days recovery period. The brains of all rats were prepared for histological, ultrastructural, immunohistochemical and morphometric investigations. Results indicate that SS exposure led to disrupt the structure of auditory cortex (AC) represented by reduction in the cell number and the thickness of AC. The stellate cells appeared darkly stained nuclei, microglial cells appeared with dilated perineuronal spaces around them, many pyramidal cells appeared destructed and poorly stained vacuolated neuropil was noticed. The cytoplasm of the cells had damaged mitochondria, numerous vacuoles, dilated rough endoplasmic reticulum cisterna, and vacuolations. There was extensive loss of synaptic vesicles. There was an apparent increase in positive glial fibrillary acidic protein (GFAP) immunoreactivity in the astrocytes. After the recovery period, the histological structure of AC has improved. Conclusions: SS induced deleterious changes in AC of adult rats. These changes were reversible after SS withdrawal.