Researchers at the University of Nevada, Reno
have asked whether taking long courses of antibiotics reduces the sperm count in human males. To test this theory, they conducted research on male scorpions treated with doses of tetracycline.
The research team was led by Jeanne Zeh
and the project was funded by the National Science Foundation, which is investigating factors contributing to low male fertility.
For the research, the scientists examined the pseudoscorpion, [i]Cordylochernes scorpioides[/i]
, a small scorpion-like arachnid, over three generations. In the first generation, 21 families were examined and half of the brothers and sisters were treated with weekly doses of tetracycline from birth to adulthood or and the other-half were untreated controls.
In the University of Nevada research summary
, it was found that the antibiotic had no effect on male or female body size, sperm number or female reproduction. However, the research findings also showed that the scorpions suffered significantly reduced sperm viability and went onto pass this toxic effect on to their untreated male offspring (a so-called "transgenerational effect").
It is theorized that antibiotics alter the expression of genes in male reproductive tissues. Tetracycline was chosen for the study because it is a broad spectrum antibiotic and one commonly used in animal production and for antimicrobial therapy. The medical industry commonly uses Tetracycline antibiotics to fight bacterial infections in the urinary tract and intestines, severe acne, rosacea and chlamydia.
The implications of the research findings are that a similar effect may occur in people.
For reference, the research paper
Jeanne A. Zeh, et al. From father to son: transgenerational effect of tetracycline on sperm viability. Scientific Reports, 2012.