Investigating the Effects of Shirazi Thyme Extract on Plasma Levels of Testosterone, Dihydrotestosterone, LH and FSH in Adult Male Wistar Rats: An Experimental Study

Thymus vulgaris contains components that are chemically very different. Some of these components have properties as anticonvulsant, antifungal, antioxidant, anti-inflammatory, anti-infection, anti-diabetics and act as a stimulant to central nervous system, stimulating the production of testosterone hydroxylase. The present study aimed at investigating the effect of intraperitoneal injection of hydroalcoholic extracts of Shirazi Thyme on plasma levels of testosterone, dihydrotestosterone, LH and FSH in adult male Wistar rats, conducting histological studies on testis in this regard. In this study, 48 male Wistar rats, weighing about 190-210 gr were randomly divided into 6 groups (n=8). Control group received nothing. Sham group intraperitoneally received 2/0 distilled water daily. For 28 consecutive days, the experimental groups 1, 2, 3 and 4 intraperitoneally received Shirazi Thymus extract with daily doses of 100, 200, 300 and 400 mg/ kg of body weight. At the end of the day 28, blood samples were taken from the heart. The samples were then collected to measure the hormones LH, FSH, testosterone and dihydrotestosterone. The results were assessed using the tests Anova, Tukey and Duncan. After blood sampling, the testes were removed and studied histologically. The mean body weight, testes weight, and plasma concentrations of FSH and dihydrotestosterone in different experimental groups did not reveal any significant differences compared to the control group. Moreover, the histological changes, with respect to the size, the interstitial space, and tubules structure, were not detected in the seminiferous tubules. In terms of size, density, cytoplasm and nucleus features, the histological changes in spermatogonia, primary spermatocytes, Sertoli cells and Leydig were not recognized in the experimental group compared to the control group. However, the mean plasma concentrations of LH and testosterone in the fourth experimental group taking 400 mg/kg/day showed a significant increase in comparison to the control group. The histological changes in the seminiferous tubules were significant in terms of their number, density of tubules, and spermatozoids density in all experimental groups compared to control group which was also much more detected in more cases while increasing the dose. The use of Shirazi thyme leads to an increase in testosterone, influencing LH concentration through its effect on sympathetic nerves and consequently increasing the number of receptors on Leydig cells. Through inducing P450 (cholesterol desmolase enzyme), Cineole existed in Shirazi Thymus vulgaris extract causes increasing the conversion of cholesterol to pregnenolone in the mitochondria which in turn triggers the increase of synthesis of steroids, including testosterone.