Monosodium glutamate (MSG) is one of the most widely spread food additives that might cause male
infertility. However, Nigella sativa L. seeds (NSS) could provide a solution. This study was designed
to investigate the potential effects of NSS on rats ingesting MSG. To achieve this aim, adult male
albino rats were randomly equally assigned into three groups for 21 days: control group received no
treatment, MSG group received MSG as 30 g/kg feed, and MSG + NSS group received MSG as 30 g/kg
and NSS as 30 g/kg feed. Testis histomorphometry showed marked deterioration by MSG as atrophic
seminiferous tubules with degeneration of their lining cells, damaged Leydig cells and decreased
germ cells number. Periodic Acid Schiff stain indicated irregular interrupted basement membranes.
Glutathione reductase, superoxide dismutase 2 (SOD2), and caspase‑3 immuno‑expressions increased
in testicular cells. Testosterone levels were significantly decreased in MSG challenged rats along with
significant increase in luteinizing hormone levels, whereas NSS normalized this hormonal profile.
MSG exposure also caused significantly increased lipid peroxides (LPO), glutathione‑S‑transferase,
and total antioxidant capacity (TAC) whereas nitric oxide and SOD2 were significantly decreased.
NSS succeeded in rebalance LPO and TAC and ameliorated the histoarchitectural disturbances. NSS
mitigated MSG‑induced testicular impairment by its antioxidant and cytoprotective activities.