Gossypol is a natural compound extracted from the seeds of some species of cotton plants (Gossypium species). Gossypol displays various drug properties, including male antifertility, anti- proliferative activity on tumor cells (leukemia, prostate, adrenal, etc.) and endometriosis.
Recently, the action of gossypol has been thought to induce apoptosis in the target cells especially male testicular tissue. The current study was planned to evaluate the effect of oral intake of gossypol on the expression of anti-apoptotic Bcl-2 gene in the interstitial cells of Leydig and primary spermatocyte cells of adult rabbit.
Thirty adult male rabbits were used, subdivided into 5 equal groups. Group1 represented control group, groups 2, 3, and 4 represented rabbits intubated with 1.05mg/day gossypol suspended in 1ml. olive oil for 3,6 and 9 weeks respectively. Group5 rabbits were subjected to gossypol oral intake in the same manner for 9weeks and were left for another 9weeks as recovery periods.
All rabbits were sacrificed after 24hrs from last dose except group5 rabbits, testes were extracted fixed in neutral buffered formol and histologically processed for 5um paraffin sections. Detection of Bcl-2 protein was done by using labeled streptavidin biotin technique with the monoclonal Bcl-2 antibody.
The evaluation of Bcl-2 expression in the interstitial cells of Leydig and primary spermatocyte cells, as an optical density, were done by the aid of image analysis system. The obtained data were statistically analyzed by using student t-test.
The study showed that there was a positive Bcl-2 expression in the interstitial cells of Leydig in all study groups, and there were statistically significant increase in the Bcl-2 expression in groups 2, 3 and 4 in comparison to control rabbits values (p<0.001). The recovery group rabbits showed a statistically significant decrease in the Bcl-2 expression (p<0.001) in comparison to control rabbits values.
The primary spermatocyte cells showed a very weak Bcl-2 expression in control group rabbits and rabbits of groups 2 and 3.
After 9weeks gossypol administration there was a positive Bcl-2 expression in some primary spermatocyte cells (p<0.001) and the overexpression of Bcl-2 was continued in the recovery group rabbits (p<0.001).
The study concluded that gossypol may trigger Bcl-2 expression in interstitial cells of Leydig, which started after 2weeks of oral administration and this effect is diminished after cessation of oral intake. Also there was an increase in Bcl-2 protein expression in primary spermatocyte cells after 9weeks of oral gossypol intake and that increase persisted even after cessation of gossypol.
The study recommends further study about the role of gossypol on the relation between apoptosis inducing gene and apoptosis inhibiting gene in the testicular tissues.