SUMMARY AND CONCLUSION
Titanium dioxide (TiO2), known as titanium oxide or titania is naturally occurring oxide of titanium which exists in three forms: rutile, anatase and brookite. There are some differences in physical (crystal structure, stability, hardness and density) and optical (color, luster, brightness and refractive index) properties between them (Markowska – Szczupack et al., 2011).
TiO2 is widely used to provide whiteness in products such as paints, plastic and paper and is also a permitted color in foodstuffs. It is also used in cosmetic and skin care products, particularly in sunscreen, where it helps to protect the skin from ultraviolet (UV) light due to its effective ability to block long-wave UV (Zhang et al., 2012).
Moreover, TiO2 has been proved to be highly efficient in killing antibiotic resistant bacteria by destroying bacterial spores. It was found that the bacterial spore destruction was attributed to the highly oxidizing radicals generated by it (Brunet et al., 2009).
Titanium either pure or in alloys is extensively used for a wide range of implanted medical devices, such as dental implants, joint replacements, cardiovascular stents, and spinal fixation devices, due to its advantageous combination of physico-chemical and biological properties. However, under mechanical stress or altered physiological conditions such as low pH, Titanium – based implants can release large amounts of particle debris, both in the micrometer and nanometer size range (Vamanu et al., 2008).
The objective of the present study was to demonstrate the effect of low and high doe TiO2 exposure on testis of adult male albino rats and the effect of withdrawal of TiO2 those testis.
This work was performed on 40 adult male albino rats.
The animals were divided as follow:
(1) Group I : Control group: (10 animals).
(2) Group II: (low dose group) 10 animals: intraperitoneally injected with 200 mg/kg nanosized TiO2 and equal volume of saline every other day for 5 times. The animals will be sacrified after 10 days (Guo et al., 2009).
(3) Group III: (high dose group) 10 animals: intraperitoneally injected with 500 mg/kg nanosized TiO2 and equal volume of saline every other day for 5 times. The animals will be sacrified after 10 days (Guo et al., 2009).
(4) Group IV: (withdrawal group) 10 animals: intraperitoneally injected with 500 mg/kg nanosized TiO2 and equal volume of saline every other day for 5 times and other 10 days from last injection the animals will receive saline only then sacrificed (Guo et al., 2009).
By the end of the experiment the animals were anesthetized, sacrificed and from each animal the two testes were taken and divided transversely into 2 halves. One half was processed for paraffin sections for L/M examination and the other half was processed for E/M examination.
Testicular tissue samples were stained with hemotoxylin and eosin for histological evaluation. Also immunohistological staining for caspase 3 to detected apoptosis.
Tissue sections were examined by transmission electron microscope (T.E.M).
Histological examination of testicular tissue structure of adult rats revealed the following results:
Control group (Group 1) showed normal structure of testis, S.Ts., spermatogenic cells, sperms, Sertoli cells, Leydig cells, myoid cells and B.M of S.Ts.
Low dose group (Group II) showed apparently normal structure of testis – S.Ts, spermatogenic cells, sperms, sertolicells, leyding cells, myoid cells & basement membrane of S.Ts.
High dose group (Group III) showed severe inflammation, vaculation and degeneration of S.Ts, shedding of their germinal epithelium. The interstitium show marked edema, inflammation and congestion. Microtubular structure of sperms didn't change but their number decrease.
Withdrowal group (group IV) showed improvement of testicular tissue structure. Most S.Ts. were apparently regular in shape and size. There was normal spermatogenic cells, sperms, Sertoli cells, Leydig cells & B.M. of S.Ts. was thin & regular. The vacuolations in group decrease and the cytoplasm of all cells returned to near normal. Spermatic count apparently increased.
In conclusion, in the present study the use of low dose of TiO2 has no testicular toxic effect but the use of high dose of TiO2 has testicular toxicity and this toxic effect marked improved after withdrowal of TiO2.
So low dose of TiO2 NP has no obvious effect on testes but only high dose of TiO2 NP has significant toxic effect on testes.
This effect is reversible after withdrawal of TiO2NP.
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