“우울증, 비만 치료제 남성에게 효과 없어” Scientists Uncover a Difference Between the Sexes

美 연구진, 엔도카나비노이드 분비 조절 치료제 

암수 쥐에 투여 수컷 쥐에는 효과 없어

source socgen.ucla.edu

edited by kcontents 

케이콘텐츠 편집

지도를 보는 일은 남성이 강하고, 냉장고에서 물건을 찾는 일에는 여성이 강하다.  ‘화성에서 온 남자 금성에서 온 여자’라는 말이 나온 것처럼 남녀 사이에는 선천적인 차이가 존재한다. 미국 연구진이 남성과 여성의 뇌는 생각뿐 아니라 약물에 대한 반응도 다르다는 사실을 알아냈다.   캐서린 울리 미국 노스웨스턴대 신경생물학과 교수팀은 뇌에서 쾌감을 느끼게 하는 신경전달물질인 ‘엔도카나비노이드’ 조절 약물이 남성에게는 효과가 없다는 연구결과를 학술지 ‘신경과학저널(Journal of Neuroscience)’ 12일자에 밝혔다.   엔도카나비노이드는 스트레스나 통증을 느끼면 분비되는 신경전달물질로 고통과 긴장감을 해소하는 역할을 한다. 화학 성분이 대마초와 흡사해 ‘천연마약’이라고도 불리며 분비되면 평소보다 입맛이 좋아지기 때문에 비만의 원인으로 꼽히기도 한다.   연구진은 암컷과 수컷 쥐를 대상으로 엔도카나비노이드의 분비를 조절하는 우울증·비만 치료제인 ‘URB-597’의 효능을 평가했다. 그 결과 암컷 쥐의 경우 URB-597를 투여하면 엔도카나비노이드의 분비가 줄었지만, 수컷쥐의 경우 약을 투여해도 변화가 없다는 사실을 발견했다.   엔도카나비노이드는 기억, 자극, 식욕 등에 관여하는 뇌 부위에서 분비되는 물질이다. 이번 연구로 연구진은 뇌신경계에 관여하는 약물의 효능도 남녀 차이가 존재한다는 사실을 처음 알아낸 것이다. 하지만 연구팀은 이번 연구가 쥐를 대상으로 진행됐기 때문에 사람에서도 동일한 결과를 나타낼지에 대해서는 추가 연구가 필요하다고 밝혔다.   울리 교수는 “신경과학분야 기초연구 중 85%가 수컷 동물을 활용해 진행되고 있다”면서 “신약의 부작용을 줄이기 위해 개발 과정에서부터 양성을 모두 사용한 연구를 진행할 필요가 있다”고 말했다. 동아사이언스 권예슬 기자 yskwon@donga.com

Scientists Uncover a Difference Between the Sexes

Sex does matter: key molecular process in brain is different in males and females 

by Megan Fellman

EVANSTON, Ill. --- Male and female brains operate differently at a molecular level, a Northwestern University research team reports in a new study of a brain region involved in learning and memory, responses to stress and epilepsy.

Catherine Woolley

Many brain disorders vary between the sexes, but how biology and culture contribute to these differences has been unclear. Now Northwestern neuroscientists have found an intrinsic biological difference between males and females in the molecular regulation of synapses in the hippocampus. This provides a scientific reason to believe that female and male brains may respond differently to drugs targeting certain synaptic pathways. 

“The importance of studying sex differences in the brain is about making biology and medicine relevant to everyone, to both men and women,” said Catherine S. Woolley, senior author of the study. “It is not about things such as who is better at reading a map or why more men than women choose to enter certain professions.”

Among their findings, the scientists found that a drug called URB-597, which regulates a molecule important in neurotransmitter release, had an effect in females that it did not have in males. While the study was done in rats, it has broad implications for humans because this drug and others like it are currently being tested in clinical trials in humans.

“Our study starts to put some specifics on what types of molecular differences there are in male and female brains,” Woolley said. 

Woolley is the William Deering Chair in Biological Sciences, professor of neurobiology in the Weinberg College of Arts and Sciences and a member of the Women’s Health Research Institute at Northwestern University Feinberg School of Medicine.

The study of inhibitory synapses and endocannabinoids, which regulate neurotransmitters, was published today (Aug. 12) in The Journal of Neuroscience. It is the first study to detail where males and females differ in a key molecular pathway in the brain. 

“We don’t know whether this finding will translate to humans or not,” Woolley said, “but right now people who are investigating endocannabinoids in humans probably are not aware that manipulating these molecules could have different effects in males and females.”

Specifically, Woolley and her research team found that in female brains the drug URB-597 increased the inhibitory effect of a key endocannabinoid in the brain, called anandamide, causing a decrease in the release of neurotransmitters. In male brains, the drug had no effect. (The difference is not related to circulating reproductive hormones.)

The subject of many clinical trials, endocannabinoids are molecules that help regulate the amount of certain neurotransmitters released at synapses, the gap between neurons. These molecules are involved in a variety of physiological processes including memory, motivational state, appetite and pain as well as in epilepsy, a neurological disorder. (Their name comes from the fact that endocannabinoids activate the same neural receptors as the active ingredient in marijuana.)

Understanding what controls the synthesis, release and breakdown of endocannabinoids has broad implications both for normal and pathological brain function, Woolley said. This study contributes an important piece of knowledge.

For 20 years, Woolley actively avoided studying sex differences in the brain until her own data showed her that differences between females and males were real. Her discovery, reported in 2012, that estrogens decreased inhibitory synaptic transmission in the brains of female rats but not in males, changed her thinking. 

“Being a scientist is about changing your mind in the face of new evidence,” Woolley said. “I had to change my mind in the face of this evidence.”

Building on these earlier findings, Woolley and her team used a series of electrophysiological and biochemical studies to pinpoint what causes this effect. The researchers found the difference between males and females lies in the interaction between the molecules ERalpha and mGluR1. Details of the molecular pathway are reported in the new study.

To find out what is the same and what is different between males and females, scientists need to study both sexes, Woolley maintains. Currently, about 85 percent of basic neuroscience studies are done in male animals, tissues or cells. 

“We are not doing women -- and specifically women’s health -- any favors by pretending that things are the same if they are not,” Woolley said. “If the results of research would be different in female animals, tissues and cells, then we need to know. This is essential so that we can find appropriate diagnoses, treatments and, ultimately, cures for disease in both sexes.”

The National Institutes of Health (grant R01 NS037324) and the NIH Office for Research on Women’s Health supported the research.

The paper is titled “Sex Differences in Molecular Signaling at Inhibitory Synapses in the Hippocampus.” 

In addition to Woolley, other authors of the paper are Nino Tabatadze (first author), Guangzhe Huang, Renee M. May and Anant Jain, all of Northwestern.

http://www.northwestern.edu/newscenter/stories/2015/08/scientists-uncover-a-difference-between-the-sexes.html

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