INVESTIGATIVE UROLOGY

Effects of peppermint teas on plasma testosterone, follicle-stimulating hormone, and luteinizing hormone levels and testicular tissue in rats
Akdogan M, Ozguner M, Kocak A, Oncu M, Cicek E
Department of Biochemistry, Department of Histology-Enbriology, Department of Pharmacology, Suleyman Demirel University Medical School, Isparta, Turkey
Urology 2004; 64: 394-8

• Objectives: To justify the effects of Mentha piperita labiatae and Mentha spicata labiatae herbal teas on plasma total testosterone, luteinizing hormone, and follicle-stimulating hormone levels and testicular histologic features. We performed this study because of major complaints in our area from men about the adverse effects of these herbs on male reproductive function.
• Methods: The experimental study included 48 male Wistar albino rats (body weight 200 to 250 g). The rats were randomized into four groups of 12 rats each. The control group was given commercial drinking water, and the experimental groups were given 20 g/L M. piperita tea, 20 g/L M. spicata tea, or 40 g/L M. spicata tea.
• Results: The follicle-stimulating hormone and luteinizing hormone levels had increased and total testosterone levels had decreased in the experimental groups compared with the control group; the differences were statistically significant. Also, the Johnsen testicular biopsy scores were significantly different statistically between the experimental groups and the control group. Although the mean seminiferous tubular diameter of the experimental groups was relatively greater than in the control group, the difference was not statistically significant. The only effects of M. piperita on testicular tissue was segmental maturation arrest in the seminiferous tubules; however, the effects of M. spicata extended from maturation arrest to diffuse germ cell aplasia in relation to the dose.
• Conclusions: Despite the beneficial effects of M. piperita and M. spicata in digestion, we should also be aware of the toxic effects when the herbs are not used in the recommended fashion or at the recommended dose.
  
  
• Editorial Comment
  This is the first report concerning the effects of peppermint tea on plasma total testosterone, LH, and FSH levels and testicular histologic features.
  Peppermint tea is generally considered a safe drink for regular consumption. The authors demonstrate that both M. piperita and M. spicata tea intake decreased plasma testosterone and increased plasma LH and FSH levels in rats. Histologic studies revealed extensive degenerative changes in the germinal epithelium and spermatogenesis arrest when compared to controls.
  Changes in the pituitary-testicular axis may be responsible for the testicular maturation arrest. The statistically significant decrease in both spermatogenesis and plasma total testosterone levels in the experimental groups was associated with an increase in the plasma FSH and LH levels. These observations prompted the authors to consider the pituitary-testicular axis. The plasma total testosterone levels had decreased and plasma FSH and LH levels increased, as expected. Therefore, the mechanism of spermatogenic abnormalities was more likely a result of the direct effect on germinal epithelium, and the hormonal deficit appeared to be a result of Leydig cell dysfunction. The pituitary gland or hypothalamus may also be affected, and the maturation arrest could have been the result of hypothalamic-pituitary-testicular axis deficiency. However, this hypothesis should be elucidated by additional studies focused on the hypophysial or hypothalamic tissues.
  Consumption of M. piperita and M. spicata teas affected spermatogenetic activity at the 20 g/L and 40 g/L dose, respectively, in rats. The authors remember us that despite M. piperita and M. spicata beneficial effects in digestion, people should be aware of their toxic adverse effects when not used in the recommended fashion or at the recommended dose.

Dr. Francisco J.B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, Brazil