Abstract

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.