Marijuana Use may hit fertility in men
A new study published in the journal Epigenetics has reported that the use of Marijuana may impact fertility in men as it may trigger structural and regulatory changes in the DNA of users’ sperm.
The report has revealed that the active ingredient present in marijuana, tetrahydrocannabinol (THC), could impact the sperm of men in their child-bearing years and possibly the children they conceive during periods when they have been using the drug.
The Duke research has shown that THC also affects epigenetics much like tobacco smoke, pesticides, flame retardants, and even obesity. Epigenetic modifications to the genome, including DNA methylation, play an essential role in regulating gene activity over the life course and have been implicated as a potential mechanism underlying the heritable effects of pre-conception cannabis exposure.
“What we have found is that the effects of cannabis use on males and their reproductive health are not completely null, in that there’s something about cannabis use that affects the genetic profile in sperm,” said Scott Kollins, Ph.D., professor in psychiatry and behavioral sciences at Duke and senior author of the study.
Experiments in rats and a study with 24 men found that THC appears to target genes in two major cellular pathways and alters DNA methylation, a process essential to normal development. One of the pathways is involved in helping bodily organs reach their full size; the other involves a large number of genes that regulate growth during development. Both pathways can become dysregulated in some cancers.
The study defined regular users as those who smoked marijuana at least weekly for the previous six months. Their sperm was compared to those who had not used marijuana in the past six months and not more than 10 times in their lifetimes.
The investigators found that the higher the concentration of THC in the men’s urine, the more pronounced the genetic changes to their sperm were.
“THC appeared to impact hundreds of different genes in rats and humans, but many of the genes did have something in common -- they were associated with two of the same major cellular pathways, “said lead author Susan K. Murphy, Ph.D., associate professor and chief of the Division of Reproductive Sciences in obstetrics and gynecology at Duke.
“In terms of what it means for the developing child, we just don’t know,” Murphy said. It’s unknown whether sperm affected by THC could be healthy enough to even fertilize an egg and continue its development into an embryo, she said.
At present, it is still unclear whether DNA methylation changes identified in sperm as a result of environmental exposures are capable of being passed on to the next generation. Recent reports indicate that a great deal more sperm DNA methylation is retained and not erased, as previously thought, during post-fertilization epigenetic reprogramming.
The researchers plan to continue its research with larger groups to evaluate the functional significance of the present findings, especially in light of evidence supporting intergenerational effects. If there is evidence that the epigenetic changes observed in this study are maintained post-fertilization, such findings should be considered with regard to cannabis use policy decisions worldwide.