It is well
understood that cocaine use, besides for concentrating in the brain,
concentrates at high levels in the testes.57 Cocaine binds to
spermatozoa and impair spermatogenesis, causing tails of sperm to separate from
their heads. Cocaine may pass to a fertilized ovum after binding to sperm.56
Cocaine has also been implicated in causing epigenetic changes through sperm
and causing intergenerational genetic modifications.
have shown that paternal preconception exposures to cocaine can cause decreased
cerebral volume and decreased weight in offspring and shortened attention spans
in male offspring. Learning deficits in female offspring are also observed.44
Male progeny of
male mice that self-administered cocaine had decreased levels of cocaine intake
as adults. It is hypothesized that this may be due to impairments in the reward
and motivational circuits of the offspring brain, which decreases their ability
to self-administer cocaine.44 This finding is at odds with human
epidemiological data that indicates that cocaine addiction is passed on through
The impacts of
cocaine may be due to its ability to bind to sperm and pass into the mother,
resulting in a direct maternal exposure. However, some epigenetic mechanisms of
action have been proposed. Mice that self-administered cocaine had decreased
levels of DNA methyltransferase 1 in the seminiferous tubes of the testis. DNA
methyltransferase helps maintain imprinted genes in germ cells, and without it
genetic expression may be altered.44 Additionally, cocaine use may
change histone 3 acetylation which results in chromatin remodeling and altered
gene transcription.44 Further epidemiological and epigenetic studies
on paternal preconception cocaine use must be done.
There are many
other drugs that may cause damage to offspring after paternal preconception
exposure. For example, some research has been done on opioid use, like
morphine. Male rats who were administered morphine during adolescences produced
smaller litters with modified endocrine function. Parental exposure to opioids
also leads to increased sensitivity to opioids and blunted response to dopamine
agonists in offspring. This may indicate an increased risk of opioid use in
offspring.57 Determining the epigenetic factors that may cause
susceptibility to opioid abuse is a timely task. Currently, the United States,
as well as other countries, is experiencing an opioid epidemic, with millions
dying due to opioid overdose.
the intergenerational harmful effects and priming of offspring for drug use may
be important to stopping drug epidemics.
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