Background

Cadmium (Cd) is an important cause of infertility among occupational workers.

Thymoquinone (TQ) is a medical extract from Nigella sativa (NS) and is used as a natural remedy for many diseases because of its antioxidant and anti-inflammatory properties.

Aim of the work

The aim of the study was to study the histological, immunohistochemical, and biochemical effects of TQ on Cd-induced toxicity of Leydig cells in adult male albino rats.

Materials and methods

Forty adult male rats were included in the study and were divided equally into four

groups: group I, group II, group III, and group IV. Group I was the control group.

Group II received a daily oral dose of Cd at 0.5 mg/kg by means of a gastric tube for

6 weeks. Group III received a daily oral dose of TQ at 100 mg/kg through a gastric

tube for 6 weeks. Group IV received TQ, followed by Cd, at the same dose for 6

weeks. Specimens of the right testis were taken and processed for light microscopy

(stained with H&E) and electron microscopy (stained with toluidine blue for semithin

sections) to evaluate the structure of Leydig cells. Morphometric study of Leydig

cells stained immunohistochemically by testosterone Ab-1 was carried out, and

biochemical measurements of serum total testosterone and luteinizing hormone were

taken, followed by statistical analysis.

Results

Microscopic study of group II showed apoptotic shrunken Leydig cells with deeply

acidophilic cytoplasm and deeply stained nuclei, whereas electron microscopic

results showed few mitochondria, few Smooth endoplasmic reticulum (sER),

large cytoplasmic vacuoles, and heterochromatin margination. This was confirmed

immunohistochemically by significant decrease in the area% of testosterone Ab-1

and biochemically by significant decrease in serum total testosterone and significant

increase in serum luteinizing hormone. Group III showed similar results to group

I, whereas group IV showed improvement in the histological, morphometric, and

biochemical changes described for group II.

Conclusion

TQ has a protective effect on Cd toxicity-induced Leydig cell damage as it has

antioxidant and anti-inflammatory activities. It is suggested that workers dealing with

Cd consume a diet rich in TQ, such as Nigella sativa.