This study was designed to investigate the effect of administrating a selective AROMATASE INHIBITOR, letrozole, on the parameters of the rat's sperm and testicular histomorphology. A total of 40 male Wistar rats with an age of about 5 months old and an average weight of 190±, 10 g were divided randomly into 4 groups (n=10 each) and treated for 6 weeks. The first group (C) was given normal saline only as a control group. The second (T1), third (T2), and fourth (T3) groups received doses of 0. 5, 1, and 1. 5 mg/animal letrozole, respectively. At the end of the experiment (42 days), all animals were euthanized and the samples were obtained for more evolutions. The results of this study showed a significant increase in sperms quality (P-value≤, 0. 05) while indicating a significant decrease in sperm abnormality in the T1 group, compared to the C group. Moreover, there was a significant difference represented by an increase in sperm quality, and a significant difference represented by a decrease in sperms abnormality in the T2 group, compared to the C group. On the other hand, there was a significant difference represented by an increase in sperm quality, and a significant difference represented by a decrease in sperm abnormality in the T3 group, compared to the T2 group. Normal somniferous tubules with high spermatoscopy counts were shown in histologic sections in the control group, primary and secondary spermatocytes with spermatozoa. In the T1 group, there was adequate spermatogenesis with a thick basement membrane. In the T2 group, there was normal testicular tissue with a significant increase in spermatogenic activity and number. In the T3 group, there was no significant atrophy or other pathology. The results of the current study suggested that letrozole improved spermatogenesis while causing no visible pathological alterations in testis tissue.

Objective: to investigate the effects of administrations of AROMATASE INHIBITOR and anti-estrogens on sex differentiation.Material and Methods: Eggs were divided into five groups of 60, one control group receiving distilled water and four test groups. All groups were placed inside the incubator. Injection of anti-AROMATASEs was performed in fifth day of incubation. First test group received 1mg/egg AROMATASE INHIBITOR (AI), second test group received 1mg/egg Tamoxifen, third test group received 1 mg/egg Clomiphene and forth test group received 1mg/egg GAR79 respectively. Chickens were determined after hatching on first day using Feather Sexing method. Redetermination was performed after 45 days for more insurance. In this study 14-a-hydroxy 3,6,17, androstantrion INHIBITORs with dose of 1 mg/egg were injected.Results: Administration of anti-AROMATASEs into the eggs during incubation period causes production of male fetus about %72 to %84 that in comparison with control group (%52.5 male) showed an increase of %20 to %34 (P³0.05). The sex reversed females have bilateral testes with ability of complete spermatogenesis and also the physical appearance and behavior of normal males.Conclusion: Results showed the significant role of AROMATASE in sex differentiation. Moreover, results showed GAR79 as an anti-AROMATASE could affect AROMATASE activity in sex differentiation.

Background: AROMATASE is an enzyme converts androstenedione and testosterone to estrone and estradiol, respectively. According to the role of testosterone and zinc in reducing anxiety and the relation between androgenic system function and zinc supplementations, in this research, the effect of zinc chloride injection was analysed in rats which AROMATASE enzyme was inhibited by AROMATASE INHIBITOR (letrozole).Materials and Methods: Adult male Wistar rats (weighing 225±25 g) were used. Animals were divided into 12 groups and based on their weight, AROMATASE INHIBITOR (letrozole) was injected (subcutaneously), and 30 minutes later, ZnCl2 or its solvent (saline) was injected intra- peritoneal. Control group was received both solvents (DMSO and saline) respectively. Anxiety levels were tested in the elevated plus maze 30 minutes after the last injection, and thereafter, open field was used for measurement of the locomotors activity of animals.Results: The results showed a significant decrease in the percentage of time spent in open arms in letrozole (1.25 mg/kg) treated group as compared to that of solvent group. The locomotors activity significantly decreased between letrozole (1.25 mg/kg) with the control group. The combined groups received letrozole (2.5 mg/kg) and different amounts of zinc chloride (2.5, 5, 10 mg/kg), significantly reduced (p<0.05) the percentage of time spent in the open arm, comparing to the control group. Groups that received the combination of zinc chloride (2.5 mg/kg) and different amounts of letrozole (1.25, 5, 10 mg/kg), showed no significant difference in the percentage of entry and time spent in the open arms.Conclusion: Totally, the present study suggests that letrozole alone increased anxiety and decreased locomotors activity and could interfere with anxiolytic effect of ZnCl2 as well.