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Abstract
Radiation therapy is widely used, because there is often no other choice for the treatment of a number of cancers in children and adults. Infertility is one of the side effects, frequently occurs in men treated for cancer with radiotherapy. Therefore, the prevention of gonadal damage during radiotherapy is a major concern. Shielding the testis offers only poor protection to spermatogenesis. At the same time, hormonal treatment given prior to irradiation compromises the patient health, due to the waiting period before radiotherapy can be started. Hence, the concurrent study aimed at studying the effects of low dose gamma irradiation on rat testis, and whether administration of testosterone immediately following irradiation could reverse these determined effects, or not.
Thirty six adult male albino rats, of the Sprague-Dawely strain, aging from four to six month, were subjected to doses of 3.5 Gy or 6 Gy gamma irradiation. Following irradiation, the rats were treated with testosterone propionate, administered in a single dose of 10 mg/kg body weight, by intramuscular injection. The rats were sacrificed after four and eight weeks following exposure to irradiation.
The rats were divided into 6 groups, each group formed of six rats.
Group ?: control group.
Group ?: irradiated group with 3.5 Gy whole body gamma irradiation for four and eight weeks.
Group ?: irradiated group with 6 Gy whole body gamma irradiation for four and eight weeks.
Group ?V: Testosterone treated group for four and eight weeks.
Group V: irradiated group with 3.5 Gy whole body gamma irradiation, followed by testosterone treatment for four and eight weeks.
Group V?: irradiated group with 6 Gy whole body gamma irradiation, followed by testosterone treatment for four and eight weeks.
At the end of each experimental period, the rats were anesthetized using ether inhalation. The abdomen was opened for exposure of the testis, which were extracted and dried. The specimens were taken from both testis, and processed for paraffin and semithin sections. The sections were examined by using light microscope.
The histological examination of the testis of irradiated rats (Groups ??, ?) showed, marked testicular damage. Most of the seminiferous tubules appeared depleted from spermatogenic cells, leading to the presence of variable degrees of vacoulation among different layers of spermatogenic cells. Some seminiferous tubules appeared shrunken, and occupied with hyaline material, while other tubules showed degeneration of the spermatogenic cells. However, after eight weeks from irradiation, some tubules of the rats irradiated with 3.5 Gy gamma irradiation (Group ?b), showed spontaneous recovery, indicated by repopulation of the tubules with different spermatogenic cells, while the seminiferous tubules of rats irradiated with 6 Gy gamma irradiation (Group ?), showed no signs of recovery. No morphological abnormalities could be detected in either Sertoli cells or Leydig cells.
Examination of rat testis treated with testosterone following exposure to 3.5 Gy gamma irradiation (Group V) revealed complete process of spermatogenesis, indicated by repopulation of the seminiferous tubules with different types of spermatogenic cells, with the presence of well developed sperms in the lumen of the tubules. Recovery was more prominent with increasing the time after testosterone administration from four to eight weeks. On the other hand, when testosterone was administrated following exposure of rats to a dose of 6 Gy gamma irradiation (Group VI), some of the seminiferous tubules appeared repopulated with different types of spermatogenic cells, while other tubules still showed depletion of spermatogenic cells, with the presence of multiple vacuoles replacing the depleted cells. So, it was difficult to deduce from these observations whether there was recovery of spermatogenesis, or not.
In conclusion, exogenous testosterone administration to rats following exposure to low therapeutic doses of whole body gamma irradiation aids in the recovery of spermatogenesis. So, it is recommended to be used in patients rendered azospermic by irradiation, or by other cytotoxic treatments, with focusing on using the most effective and safe dose of testosterone to obtain optimal results in human.