Effect of experimental orchiectomy on hippocampus of adult albino rat and the role of testosterone supplementation: a histological and immunhistochemical study

ABSTRACT

The brain is one of the target organs for the gonadal hormone 'testosterone'. The hippocampus plays a crucial role in learning and memory. It is a sensitive region for the effect of testosterone and hence is vulnerable to gradual age-related decline of testosterone level in men. This work aimed to study the histological changes in rat hippocampus after experimentally induced orchiectomy and assess the possible beneficial role of testosterone replacement. Thirty-five adult male albino rats were divided into control group [group I] and two experimental groups [groups II and III]. Rats in groups II and III were subjected to orchiectomy. The orchiectomized rats in group III were treated daily with testosterone propionate [0.5 mg/kg/day] and both groups were left alone for 30 days. At the end of the experiment, all rats were anaesthetized and their brains were removed and processed. Sections were stained by H and E and immunohistochemically for Bax, BcIe, and glial fibrillary acidic proteins [GFAP]. Further, the serum level of testosterone was measured. The results were statistically analysed. Examination of the hippocampus of orchiectomized rats showed decreased thickness of the pyramidal layer, which contained many apoptotic cells. Minute haemorrhage, cellular infiltration and dilated capillaries were also seen. Immunohistochemically, intense Bax and GFAP with minimal Bcl2 reactions were detected. The hippocampi of orchiectomized rats treated with testosterone were less affected. The pyramidal cell layer thickness was relatively normal. Few nerve cells with dark cytoplasm appeared among the normal ones. Further, minimal Bax and GFAP with moderate BcI2 reaction were detected. Statistically, there was a significant decrease in the level of testosterone in group II compared with group I. The results demonstrated that decrease in the level of testosterone had deleterious histological effects on rat hippocampi. Testosterone replacement ameliorated these histological changes after orchiectomy