histomorphometric evaluation of the testis after administration of methionine-loaded zinc oxide nano-particles in mice

With the remarkable progress of nanotechnology in medicine, the use of nano supplements such as methionine in low doses can be a starting point for the optimization and strengthening of the compounds that protect the testes and, subsequently, the improvement of the fertility rate of the population. excessive amounts of methionine, an essential amino acid in mammals, have toxic effects on body organs. the beneficial effects of widely used and inexpensive zinc oxide nanoparticles (zno-nps) with high antioxidant properties have been shown on the male reproductive system. this study was conducted to examine the histopathologic and histomorphometric effects of methionine-loaded zinc oxide nanoparticles on mice testes. adult male mice (n = 50) were assigned to five groups (n = 10 in each group) randomly. the groups included m50 (50 mg/kg methionine), m200 (200 mg/kg methionine), nm50 (50 mg/kg methionine-loaded zinc oxide nanoparticles), nm200 (200 mg/kg methionine-loaded zinc oxide nanoparticles), and control. after 42 days, the left testes of the mice were assessed for johnsen scores, seminiferous tubule epithelium height, seminiferous tubule diameter, meiotic index, rate of spermatogenesis, and histopathological features after euthanasia. the results showed that high doses of methionine (alone and attached to nano zinc oxide particles) have toxic effects on the testes. in comparison to the control group, the histopathological and histomorphometric indicators of the testis in the group receiving methionine at a dose of 50 mg/kg attached to nano zinc oxide particles had some increase (although insignificant), with better status compared to the m50 group. high doses of methionine could have undesirable effects on testes and significantly decrease the mentioned parameters. however, the results indicated that the histomorphometric indices of mice testis may benefit from zinc oxide nanoparticles loaded with methionine.