Marijuana as a Teratogen
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ideas
heyyy...i just finished doing all my sections...so i hope you guys check them over and make sure they are okay...i did the bottom three sections (tubal pregnancy, how mari crosses the placenta, and the challenges) if you guys think i should do any more just let me know otherwise im just going to look it over on tuesday morning and present my sections...should we just go in order as they are put on the site? also, take a look at the citations....i think they look crowded; should we fix the spacing? -Jenn
hey guys, i have been looking up some information about the effects caused by the use of marijuana while breast feeding. there seems to be some good information out there. I was also going to look up the long-term effects of pre-natal use on the the child, because I've found a couple articles on that, and because Anton's section so far seems to focus on the pre-conceptual and the genetic effects. Let me know what you guys think! Also, I know I haven't put much on the page yet, but I have two tests tomorrow that I am studying for, but I promise that I can work a ton on it tomorrow night. - Beth
http://www.health.gov.au/internet/wcms/publishing.nsf/Content/health-pubs-drug-cannab2-home.htm This is an Australian drug monograph with some information, particularly in chapter 6.5.
http://www.nida.nih.gov/pdf/monographs/monograph59/download59.html An American drug monograph also with information.****
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1651077 A real article.
http://drugsafetysite.com/marijuana Long article.
http://www.annals.edu.sg/pdf200405/V33N3p336.pdf Another study.
[Anton: Emily, your section is a good introduction. Perhaps you could add more details about how marijuana affects the adult brain just for reference? It might not be directly related to fetal development, but it might be good to just have some juicy neurological details in there.]
[Anton: Emily, I have heard and read that marijuana may cause changes to adults' DNA. Perhaps you could include some cited information about these possible mutations in the fertility section? Maybe the changes can be passed on to children who might be more sensitive to them.]
and this one http://search.marchofdimes.com/cgi-bin/MsmGo.exe?grab_id=0&page_id=1212&query=marijuana&hiword=marijuana%20
** ***a subtopic for effects could be effects on pregnant mothers versus the effects through breastfeeding***??? [Anton: I think this is a really good idea; could somebody tackle this topic? It has come up in some articles that I have read, and we need more material for this site of ours.]******
FrontPage
***marijuana education for mothers (or parents in general) could be a topic
***it would be interesting to look up if smoking before pregnancy has an effect***
this site may help http://www.medicinenet.com/script/main/art.asp?articlekey=51663
***a good point could be to compare its effects with other drugs or teratogens
***a thing i noticed about effects is there is a difference between neurological damage versus motor damage: this could be split by two people
***we could have a section for future research
***some withdrawal? http://www.narconon.ca/drugs_babies2.htm
This website is REALLY good with ideas to start thinking about and writting about: http://otispregnancy.org/pdf/marijuana.pdf
THE ACTUAL ASSIGNMENT START
What is Marijuana? pot, weed, mary jane, herb (i thought i would add this as a basis for starting feel free to add anything, i still have to sight it Emily)
Marijuana is a recreational drug that comes from the hemp plant called Cannabis Sativa. The leaves of the plant are dried and then can either be smoked or eaten. It is currently illegal in the United States however this is a highly contested point since marijuana can be used for medicinal purposes. Delta-9-tetrahydrocannabinol or THC is the active ingrediant in marijuana. THC causes an chemical reaction in the brain that causes the user to feel a high form taking the drug. Marijuana is an addictive drug however not everyone reports withdrawal symptoms.
http://www.4therapy.com/consumer/conditions/article/4539/192/What+is+Marijuana%3F
Marijuana and Fertility (Another start, again feel free to add to it- Emily)
Long term uses of marijuana can cause a lower sperm count in men and a lower rate of production of hormones that are associated with pregnancy for women. This does not mean that a woman will not become pregnant if she or her partner injest marijuana, however it could greatly lower their chances. At the same time, it seems that these effects of marijuana on fertility start to diminish once marijuana is no longer being used.
http://otispregnancy.org/pdf/marijuana.pdf
Teratogenic and Neurobiological Effects by Anton, work in progress
There is some evidence that marijuana can have teratogenic and neurological effects at various dosings, based on experimental animal studies and corellational studies of humans. more to come pending a review of the available literature
Marijuana is evidenced to cause reproductive abnormalities at several different junctures. Though not all of its effects are strictly teratogenic, in the sense that they cause developmental abnormalities directly by marijuana's interaction with the unborn child, they nevertheless result in unpleasant consequences.
Even before conception, marijuana has the potential to affect the pregnancy-- in several ways. In men, chronic marijuana use has been corellated with lower sperm quantity and quality (Bloch, 1983, National Academy of Science, 1982; Wenger et al, 1992). While this may not technically count as a teratogenic effect, a mutant sperm might contribute mutant DNA to the child and cause deformities or other abnormalities in that way. Interestingly, this effect seems to be a result of a dual action on the part of THC (the active ingredient in marijuana): on the testes themselves, which produce the sperm, and on hypothalamic secretions that interact with the testes (Wenger et al, 1992). These effects are especially pronounced for younger users of cannabis, and heavy chronic users with existing reproductive problems (Hollister, 1986). Bloch (1983) is of the opinion that a similar phenomenon occurs in women, also due to hypothalamic effects, resulting in overall lower reproductive function.
The second way in which marijuana may affect future pregnancies is a mugagenic effect. Cannabis smoke "has been ... associated with chromosomal aberrations ... such as hypoploidy, mutagenicity in the Ames test ... " (Bloch, 1983, p413). Smoking marijuana is in fact probably the most common means of consumption; THC must be "activated" by heat before it is in its effective form, and so it is typically smoked. These genetic changes brought on by the smoke may be permanent, and so could be passed on to the sperm, and then to the egg, and so on, resulting in a abnormalities in the early stages of development, which may not be significant to the already developed adult, but very significant for the still-developing conceived child.
Actual teratogenic effects of marijuana are "resorption, growth retardation, and malformations" in mice, rats, rabbits, and hamsters (Bloch, 1983, p406), with resorption and retardation more consistently reported than malformations (Abel, 1985). However, these effects have typically necessitated very large doses of crude marijuana extract. Marijuana has also been found to produce lower birth weights in mammals. This effect however, may not be direct. There are studies with mammals
Undesirable neonatal effects of marijuana that are not mechanically teratogenic include: lowered response to light stimuli, lowered habituation to the same, less "self-quieting" behavior (thumb-sucking, etc.), more tremors and increased startling, and more "cri du chat" (high-pitched cries).
Marijuana and Tubal Pregnancy
The Vanderbilt University Medical Center has experimented with mice and has found that excessive cannabis intake can result in less pregnancies; specifically, these mice had an increased number of tubal pregnancies. CB1 is a cannaboid-receptor which assists muscle contractions that moves the embryo down to the uterus, and when this receptor is blocked, over-stimulated, or not present, tubal pregnancies occur more often in mice (Snyder, 2004). It has not been concluded if these results would occur in humans, but it is advised that women who are trying to become pregnant should avoid marijuana usage. There is also an anti-obesity drug which seems to have the same effect in mice (Snyder, 2004).
How Marijuana Crosses the Placenta
Refer to the diagram above to understand the pathway of marijuana from the mother's blood to the fetus' blood. Some of the fetus' blood vessels are located in the villi of the placenta, and they extend into the wall of the mother's uterus. The mother's blood is traveling through the intervillous space which is separated from the villi by a thin placental membrane. Chemicals from marijuana are able to travel from the mother's blood through the placental membrane into the villi which contain fetal blood vessels. Once the chemicals enter, they travel from the umbilical cord to the fetus (Foley, 2007).
Challenges to Research
A lot of debate exists on whether or not marijuana should be considered a teratogen since it can not ultimately be concluded that marijuana causes birth defects. Anywhere between 5 to 30 percent of mothers reported marijuana use during their pregnancies (Plumbo, n.d.). It is difficult to determine whether developmental abnormalities that occur in infants whose mothers used marijuana are actually caused by the marijuana or by other factors. Researchers cannot separate the use of marijuana from other maternal factors such as lifestyle, previous or multiple drug use, nutrition, and lack of prenatal care (Gurnee & Sylvestri, n.d.). It has also been argued that only excessive marijuana abuse leads to complications in the exposed fetus, and this may not be because of the actual marijuana itself, but rather because of the side effects of the drug on the mother such as malnutrition (Johnson, 1998). In addition, it is possible that mothers who purchase marijuana may not have the resources to provide their baby with proper care because of their socioeconomic status.
Like any other social drug that may be considered a teratogen, there are certain factors that influence how marijuana effects the fetus. These factors include the amount of marijuana that is used, at which point in development the marijuana is used, the duration of usage, other environmental influences, and the fetus' susceptibility to the drug (Gurnee & Sylvestri, n.d.). It has been claimed that marijuana has minimal effects on a fetus if the mother smokes less than three grams of marijuana per day, which is an extremely high dosage (Johnson, 1998). There are critical periods of prenatal development in which certain aspects of development may be affected more. According to Dr. Richard S. Abram, author of Will It Hurt the Baby?, marijuana usage during the first trimester of pregnancy probably will not lead to defects (Marijuana Passion, n.d.). If a mother is exposed to other teratogens, then it is hard to conclude that marijuana usage is what caused birth defects.
There are other cultural and medical implications involving marijuana usage among pregnant mothers. A medical anthropoligist from the University of Massachusetts, Melanie Dreher, and colleagues conducted research in Jamaica during the 1980s and 1990s and found that many Jamaican pregnant mothers smoked marijuana to relieve nausea associated with morning sickness, to treat depression, to help fatigue, and to promote appetites (1994). Among these women, there were no reports of longitudinal birth defects or behaviorial problems.
Although studies on the effects of marijuana usage during human pregnancy conclude that there are minimal effects, animal studies have had different findings. Studies performed on mice, rats, rabbits, and hamsters indicate that marijuana usage can result in resorption, growth retardation, and malformations in these animals (Johnson, 1998). Although these are reliable findings in animals, no human studies have found similar results. On the other hand, studies have been done specifically on THC and its effects on human genes; it has been found that THC may reduce the body's response to infection. In addition, since THC can pass into the placenta and through breastmilk, it is advised not to use marijuana while pregnant or nursing (Kassuba, 1982). Most studies on this topic are performed on animals since it would be unethical to do human experimental-type studies using a potential teratogen.
Citations: are these supposed to be double spaced...i think each individual citation is supposed to be single spaced with two spaces between...am i wrong? this just looks crowded
Abel, E.L. (1985). Effects of prenatal exposure to cannabinoids. In T.M. Pinkert (ed) Current Research on the Consequences of Maternal
Drug Abuse. National Institute on Drug Abuse Research Monograph No. 59. Rockville, MD: U.S. Department of Health and Human Services.
Bloch, E. (1983). Effects of marijuana and cannabinoids on reproduction, endocrine function, development and chromosomes. In K.O. Fehr and
H. Kalant (eds) Cannabis and Health Hazards. Toronto: Addiction Research Foundation.
Dreher, M., Hudgins, R., & Nugent, K. (1994). Prenatal Marijuana Exposure and Neonatal Outcomes in Jamaica: An Ethnographic Study. Pediatrics, 93:2.
Retrieved September 27, 2007, from http://www.druglibrary.org/SCHAFFER/hemp/medical/can-babies.htm
Foley, M. R. (2007). Drug Use During Pregnancy. Retrieved September 27, 2007, from
http://www.merck.com/mmhe/sec22/ch259/ch259a.html
Gurnee, M.C., & Sylvestri, M.F. (n.d.). Teratogenicity of Drugs. U.S. Pharmacist, 23:9. Retrieved September 24, 2007, from
Hollister, L.E. (1986). Health aspects of cannabis. Pharmacological Reviews, 38, 1-20.
Johnson, L. (1998). The Effects of Marijuana on the Fetus. Health and Psychological Consequences of Cannabis Use. Retrieved September 24, 2007,
from http://www.a1b2c3.com/drugs/wom06.htm
Kassuba, S. L. (1982). Environmental Causes of Birth Defects. Human Fetal Development, VII. Retrieved September 24, 2007, from
Marijuana Passion. (n.d.) The Debate on the Effects of Marijuana Use During Pregnancy. Retrieved September 24, 2007, from
National Academy of Science (1982). Marijuana and Health. Washington, DC: Institute of Medicine, National Academy Press.
Plumbo, P. (n.d.). Marijuana use: Dangerous to baby-to-be? Retrieved September 24, 2007, from
http://parenting.ivillage.com/pregnancy/psafe/0,,midwife_3pcn,00.html
Snyder, B. (2004). Pot smoking could increase tubal pregnancies. The Reporter. Retrieved September 24, 2007, from
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