新研究表明:大麻或改編精子基因

We already know that cannabis lowers sperm count, but new research suggests that the drug actually causes changes to the sperm itself - which might have implications for the health of a potential baby.

我們都知道大麻會降低精子數量，但新研究表明，大麻實際上或導致精子本身發生變化--可能對即將出生的寶寶的健康產生影響。

For a study published today in the journal Epigenetics, scientists at Duke University compared the sperm of two groups of rats: those who had been given tetrahydrocannabinol (THC), the psychoactive ingredient in cannabis, and those who had not. Then they compared the sperm of 24 human men who smoked marijuana weekly versus a control group who used marijuana no more than 10 times in their life and not at all in the past half-year. In both cases - rats and humans - marijuana changed how genes work in sperm cells.

《表觀遺傳學》期刊今日發表了一篇研究：杜克大學的科學家將兩組大鼠的精子進行了對比：一組大鼠被注射了四氫大麻醇（THC，大麻中的精神活性成分），另一組沒有。之後，他們比對了每週吸食大麻的24位男性的精子與一生中使用大麻不超過10次的男性對照組（過去半年從未吸過）的精子。在這兩種情況下--大鼠和人類--大麻都改變了基因在精子細胞中的作用。

Think of your DNA as a list of instructions for making proteins, and genes as small subsets of that list. Our body has little chemical tags (called methyl groups) that get added to the DNA at specific regions, explains Susan Kay Murphy, a professor of gynecology at Duke and co-author of the study. These chemicals don't mutate the genes themselves, but they do affect how they're used, like deciding which instructions are followed and which aren't.

將DNA視爲產生蛋白質的指令列表，並將基因看作列表中的子集。我們的身體幾乎沒有可以在特定區域添加到DNA中的化學標籤（稱爲甲基），杜克大學的婦科學教授以及本研究的共同作者蘇珊·凱·墨菲解釋道。這些化學物本身不會改變基因，但它們會影響基本的使用方式，例如：哪些指令該遵循，哪些不該遵循。

In both rats and humans, the cannabis affected many different genes involved in two different pathways. (Think of pathways as another set of instructions, this time for regulating various bodily functions.) One is important for organs to reach full size, and one plays a role in cancer and suppressing tumors. "That just blows my mind," says Murphy. "How do you even reconcile that, biologically, an entire pathway is going to be affected by these changes?"

在大鼠和人類的實驗中，大麻影響了涉及兩種不同途徑的許多不同基因。（將途徑視作另一組指令，用於調節身體各種功能的指令。）一個對於器官達到完整尺寸十分重要，另一個在癌症和抑制腫瘤中發揮作用。"這一發現令我大吃一驚，"墨菲說道。"從生物學角度來看，我們又該如何協調這一變化，整個途徑將會受到這些變化的影響嗎？"

This doesn't mean that smoking cannabis will lead future children to be more vulnerable to cancer. Murphy is very clear that this is a pilot study originally intended to see if cannabis even has any effect of this kind on sperm. The sample size is small, and they didn't control for the concentration of THC the human recruits smoked. The scientists did, however, measure THC in the urine and noted that more THC in the urine correlated with more changes.

這並不是說，吸食大麻會導致將要出生的寶寶更易患癌症。墨菲表達的非常清楚：這是一項試點研究，旨在研究大麻是否會對精子產生影響。而且研究的取樣很少，他們並沒有控制受試者吸食大麻的四氫大麻醇濃度。然而，科學家的確測量了尿液中的四氫大麻醇含量，並指出尿液中四氫大麻醇越多與更大的變化相關。