One Friday afternoon, not long after Oregon made cannabis legal in 2015, some lab researchers in the state embarked on a quirky experiment.

The team worked with a type of tiny nematode worm called Caenorhabditis elegans, smaller than a human eyelash, to understand its food preferences and, on a whim, decided to soak the worms in cannabinoids — the active substances found in weed.

It turned out the worms did respond, and cannabinoids made them hungrier for their favored foods and less hungry for their non-favored food. The research ultimately revealed that the worms, like humans, engage in hedonic feeding — a phenomenon more commonly known as the munchies. “The very fact of hedonic feeding in nematodes was surprising. The munchies in a worm. Really?” said Shawn Lockery, a professor at the Institute of Neuroscience at the University of Oregon in Eugene and coauthor of a study that published last week in the scientific journal Current Biology. Previously cannabinoids were only known to affect humans and other mammals — making them want to eat more and crave the tastiest, most high-calorie foods.

The worms, however, weren’t tearing through a pile of junk food. They fed on different types of bacteria.

By measuring the swallowing rate of the worms, Lockery and his team determined that the cannabinoids were increasing how much of a particular bacteria blend the worms ate, making them hungrier. They showed the worms craved the food they found more palatable by putting them in a T-shaped maze that was baited with a preferred bacteria blend and less preferred food. The worms were also genetically engineered so that certain neurons and muscles glowed fluorescent, with green dots showing neurons that respond to cannabinoids.

Lockery added that the active ingredients in cannabis caused the worms’ “olfactory neurons to be more sensitive to preferred food and less sensitive to less preferred food,” but why this happened was “quite a mystery” so he planned to follow up on it.

In humans and other animals, cannabinoids act by binding to cannabinoid receptors in the brain, nervous system and other parts of the body, Lockery said. Those receptors normally respond to related molecules that are naturally present in the body, known as endocannabinoids. The endocannabinoid system plays important roles in eating, anxiety, learning and memory, reproduction and metabolism. At the molecular level, the cannabinoid system in these worms looks a lot like that in people and other animals.

Lockery said the research had the potential to accelerate the discovery of new medications for metabolic disorders, including obesity.

Words to Learn 相关词汇

【大麻】dàmá weed marijuana

【垃圾食品】lājī shípǐn junk food food that is high in calories but low in nutritional content

2015年一个周五下午，俄勒冈州将大麻合法化后不久，该州某实验室研究人员开展了一项古怪的实验。

该团队用秀丽隐杆线虫做实验，这种微小线虫比人类睫毛还细小。为了解它的食物偏好，研究人员一时兴起将它们浸泡在大麻素中 —— 大麻素是大麻中发现的活性物质。

事实证明，虫子确实作出了反应，大麻素使它们更想吃喜欢的食物，对不喜欢的食物没胃口。研究表明，线虫和人类一样，会因为嘴馋吃东西，也就是吃零食。

俄勒冈大学尤金分校神经科学研究所的教授肖恩•洛克里说：“线虫享受吃东西这一点令人惊讶。线虫爱吃零食是真的吗？” 洛克里是研究的合著者，论文上周发表在《当代生物学》杂志上。以前人们只知道大麻素会影响人类和其他哺乳动物，让他们吃得更多，渴望最美味、最高热量的食物。当然，虫子不会扯开零食袋狂吃垃圾食品，他们以不同类型的细菌为食。

通过测量线虫的吞咽率，洛克里和团队确定大麻素增加了线虫吃某些细菌的数量，让它们感觉更饿。他们把线虫放在一个T形迷宫中，两端分别放着它们喜欢和不那么喜欢的细菌，结果线虫明显渴望喜欢吃的细菌。

这些线虫经过基因工程改造，某些神经元和肌肉会发出荧光，绿色亮点标记对大麻素有反应的神经元。

洛克里补充说，大麻中的活性成分导致蠕虫的“嗅觉神经元对偏好食物更敏感，对不太喜欢的食物不敏感”，但为什么会这样是“一个谜”，所以他计划跟进研究。

洛克里说，在人类和其他动物中，大麻素通过与大脑，神经系统和身体其他部位的大麻素受体结合起作用。这些受体通常对体内天然存在的相关分子做出反应，称为内源性大麻素。内源性大麻素在进食、焦虑、学习和记忆、生殖以及新陈代谢方面起着重要作用。在分子水平上，这些线虫体内和人或其他动物体内的大麻素系统看起来很相似。

洛克里说，这项研究有可能帮助我们研发新药，治疗代谢紊乱疾病，例如肥胖症。(SD-Agencies)