Histological changes of the adult albino rats entorhinal cortex under the effect of tramadol administration: Histological and morphometric study

Abstract

Background: Tramadol is a centrally acting synthetic analgesic agent with opioid activity. Tramadol is used to treat moderate to severe pain. The entorhinal cortex has initially attracted attention because of its strong reciprocal connections with the hippocampal formation and its involvement in certain brain disorders.

Aim of work: The present study was designed to assess the deleterious effects of tramadol on the entorhinal cortex of the adult male albino rats.

Materials and methods: The study was carried out on 40 adult male rats. The rats were divided equally into two groups: control group, received 1 ml normal saline 0.9% intraperitoneally for 4 weeks. Treated group received 50 mg/kg/day of tramadol intraperitoneally for 4 weeks. All animals were anaesthetized by ether inhalation and perfused by normal saline. The brains were extracted from the skulls. For light microscopy, the brains of 10 animals in each group were processed for paraffin sections and stained by Gallocyanine stain. For electron microscopy, the entorhinal cortex was dissected in 10 brains of each group and processed. Semithin sections were prepared and stained with toluidine blue. Morphometric and statistical studies were performed.

Results: By light microscopy, the treated groups showed neuronal cells disorganization. Apoptotic cells were detected. In addition, diffuse chromatolysis of nuclear chromatin, absence of nucleoli, multinuclear cells, intercellular edema and a congested blood capillary were noticed. By electron microscopy, the treated groups of both lateral and medial entorhinal areas showed granular and pyramidal apoptotic cells. The morphometric and statistical studies showed significant increase of apoptotic index % in treated group as compared with control group.

Conclusion: Tramadol had degenerative effects on both lateral and medial entorhinal areas. Light as well as electron microscopic examination of entorhinal areas came to prove these effects. Tramadol abuse should be avoided without medical description due to its toxic effects.

Keywords: Tramadol; Entorhinal cortex; Rats