北卡罗来纳大学运动甚至可以燃烧骨髓中的脂肪

Exercise can even burn off fat in bone marrow

 

运动不仅可以燃烧内脏脂肪,还可以燃烧骨髓里面的脂肪

 

一项最新研究表明,锻炼可以燃烧骨髓中的脂肪。这项在老鼠身上进行的研究提供了证据,证明这一过程改善了骨骼质量,并在几周内增加了骨骼的数量。

这项发表在《骨骼与矿物质研究杂志》上的研究还表明,经常骨质质量较差的肥胖者可能比瘦人从锻炼中获得更大的骨骼健康益处。

“这项研究的主要临床意义之一是,锻炼不仅有益,而且对骨骼健康有惊人的益处,”研究报告的第一作者、北卡罗来纳大学教堂山分校(University of North Carolina at Chapel Hill)内分泌和新陈代谢学助理教授、内科医生玛雅·斯特纳(Maya Styner)说。“在很短的一段时间内,我们发现跑步在老鼠身上显著地增加了骨骼。”

“在很短的一段时间内,我们发现跑步在老鼠身上显著地增加了骨骼。”

 

虽然在小鼠身上的研究不能直接转化为人类的状况,但在小鼠身上产生骨骼和脂肪的干细胞种类与在人类身上产生骨骼和脂肪的干细胞种类相同。

除了对肥胖和骨骼健康的影响外,斯特纳说,这项研究还有助于阐明与糖尿病、关节炎、厌食症以及使用类固醇药物等病症相关的骨骼退化背后的一些因素。

斯特纳说:“我见过很多骨骼健康状况不佳的病人,我总是跟他们谈论运动对骨骼的巨大影响,不管导致骨骼状况的原因是什么。”“对于肥胖来说,你似乎可以通过锻炼获得更多的骨骼形成。”我们对骨骼生物力学的研究表明,随着锻炼的进行,骨骼的质量和强度显著提高,尤其是在肥胖者中。

神秘的骨髓

骨髓协调骨骼和软骨的形成,同时产生血细胞、免疫细胞和癌细胞。

骨髓也会产生脂肪,但骨髓脂肪在人体中的生理作用——甚至是对健康有益还是有害——仍然有些神秘。

身体细胞都源自骨髓干细胞

 

一般来说,骨髓脂肪被认为是由一种特殊的脂肪储备组成的,它在运动过程中不会像在运动过程中其他脂肪储存在全身一样被用来提供能量。新的研究提供了相反的证据。

斯特纳的研究还提供了关于骨髓脂肪如何形成及其对骨骼健康影响的基本见解。先前的研究表明,骨髓脂肪的增加会增加骨折和其他问题的风险。

锻炼的另一个原因:它可以帮助你的视力

“人们对骨髓脂肪有着浓厚的兴趣,因为它与低骨密度状态密切相关,但科学家们仍未理解其生理目的,”斯特纳说。“我们知道运动对身体其他部位的脂肪有深远的影响,我们想用运动作为了解骨髓脂肪的工具。”

胖老鼠,瘦老鼠

研究人员在两组老鼠身上进行了实验。一组喂食正常饮食(瘦老鼠),另一组在出生一个月后开始喂食高脂肪饮食(胖老鼠)。当他们四个月大的时候,每组中有一半的老鼠在接下来的六个星期里都有一个可以随时使用的转轮。因为老鼠喜欢跑步,有轮子的那一组往往会花很多时间锻炼。

研究人员分析了动物的身体组成、骨髓脂肪和不同部位的骨量。可以预见的是,肥胖老鼠的骨髓中有更多的脂肪细胞和更大的脂肪细胞。经过6周的锻炼,肥胖和瘦老鼠都显示出脂肪细胞的整体大小和骨髓中脂肪的总含量有了显著的降低。在这些方面,运动过的肥胖老鼠的骨髓脂肪与瘦老鼠的骨髓脂肪,甚至那些运动过的老鼠的骨髓脂肪,看起来几乎相同。

也许更令人惊讶的是骨髓中脂肪细胞数量的巨大差异,瘦老鼠没有变化,但与久坐不动的肥胖老鼠相比,运动的肥胖老鼠减少了一半以上。测试还显示,运动可以改善骨骼的厚度,这种效果在肥胖的老鼠身上尤为明显。

斯特纳认为,所有这些都表明,骨髓脂肪可以通过锻炼燃烧掉,这一过程对骨骼有益。

“肥胖似乎会增加骨骼中的脂肪堆积,而这个堆积就像腹部和其他脂肪堆积一样。”斯特纳说。“锻炼可以减少脂肪堆积的体积,并将其作为燃料燃烧,同时还能使骨骼更强壮、更大。”

下一个阶段

这项研究留下了一些挥之不去的谜团。一个很重要的问题是弄清楚燃烧骨髓脂肪和建造更好的骨骼之间的确切关系。可能是当脂肪细胞在运动中被燃烧时,骨髓利用释放的能量制造更多的骨头。或者,因为脂肪和骨细胞都来自于被称为间充质干细胞的母细胞,运动可能会以某种方式刺激这些干细胞产生更多的骨细胞而不是更少的脂肪细胞(注明,另一个证实了这个猜测)。

需要更多的研究来分析这个问题。“我们能说的是,有很多证据表明骨髓脂肪被用作制造更多骨骼的燃料,而不是干细胞向骨骼转移的增加,”斯特纳说。

这项研究的共同作者来自UNC和纽约州立大学石溪分校。美国国立卫生研究院资助了这项研究。

Exercise can even burn off fat in bone marrow

Exercise can burn the fat found within bone marrow, according to new research. The work, conducted with mice, offers evidence that this process improves bone quality and increases the amount of bone in a matter of weeks.

The study, published in the Journal of Bone and Mineral Research, also suggests obese individuals—who often have worse bone quality—may derive even greater bone health benefits from exercising than their lean counterparts.

“One of the main clinical implications of this research is that exercise is not just good, but amazing for bone health,” says lead author Maya Styner, a physician and assistant professor of endocrinology and metabolism at the University of North Carolina at Chapel Hill. “In just a very short period of time, we saw that running was building bone significantly in mice.”

Hear Maya Styner explain the findings:

Although research in mice is not directly translatable to the human condition, the kinds of stem cells that produce bone and fat in mice are the same kind as those that produce bone and fat in humans.

In addition to its implications for obesity and bone health, Styner says the research also could help illuminate some of the factors behind bone degradation associated with conditions like diabetes, arthritis, anorexia, and the use of steroid medications.

“I see a lot of patients with poor bone health, and I always talk to them about what a dramatic effect exercise can have on bones, regardless of what the cause of their bone condition is,” says Styner. “With obesity, it seems that you get even more bone formation from exercise. Our studies of bone biomechanics show that the quality and the strength of the bone is significantly increased with exercise and even more so in the obese exercisers.”

Mysterious marrow

Bone marrow coordinates the formation of bone and cartilage while simultaneously churning out blood cells, immune cells, and cancerous cells.

Marrow also produces fat, but the physiological role of bone marrow fat in the body—and even whether it is beneficial or harmful for one’s health—has remained somewhat mysterious.

Generally, marrow fat has been thought to comprise a special fat reserve that is not used to fuel energy during exercise in the same way other fat stores are used throughout the body during exercise. The new study offers evidence to the contrary.

Styner’s work also offers fundamental insights on how marrow fat forms and the impact it has on bone health. Previous studies have suggested that a higher amount of marrow fat increases the risk of fractures and other problems.

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“There’s been intense interest in marrow fat because it’s highly associated with states of low bone density, but scientists still haven’t understood its physiologic purpose,” says Styner. “We know that exercise has a profound effect on fat elsewhere in the body, and we wanted to use exercise as a tool to understand the fat in the marrow.”

Fat mice, thin mice

The researchers performed their experiments in two groups of mice. One group was fed a normal diet (lean mice) and the other received a high-fat diet (obese mice) starting a month after birth. When they were four months old, half the mice in each group were given a running wheel to use whenever they liked for the next six weeks. Because mice like to run, the group with access to a wheel tended to spend a lot of time exercising.

The researchers analyzed the animals’ body composition, marrow fat, and bone quantity at various points. Predictably, the obese mice started with more fat cells and larger fat cells in their marrow. After exercising for six weeks, both obese and lean mice showed a significant reduction in the overall size of fat cells and the overall amount fat in the marrow. In these respects, the marrow fat of exercising obese mice looked virtually identical to the marrow fat of lean mice, even those that exercised.

Perhaps more surprising was the dramatic difference in the number of fat cells present in the marrow, which showed no change in lean mice but dropped by more than half in obese mice that exercised compared to obese mice that were sedentary. The tests also revealed that exercise improved the thickness of bone, and that this effect was particularly pronounced in obese mice.

According to Styner, all of this points to the conclusion that marrow fat can be burned off through exercise and that this process is good for bones.

“Obesity appears to increase a fat depot in the bone, and this depot behaves very much like abdominal and other fat depots,” says Styner. “Exercise is able to reduce the size of this fat depot and burn it for fuel and at the same time build stronger, larger bones.”

Next stages

The research leaves a few lingering mysteries. A big one is figuring out the exact relationship between burning marrow fat and building better bone. It could be that when fat cells are burned during exercise, the marrow uses the released energy to make more bone. Or, because both fat and bone cells come from parent cells known as mesenchymal stem cells, it could be that exercise somehow stimulates these stem cells to churn out more bone cells and less fat cells.

More research will be needed to parse this out. “What we can say is there’s a lot of evidence suggesting that marrow fat is being used as fuel to make more bone, rather than there being an increase in the diversion of stem cells into bone,” says Styner.

Coauthors of the study are from UNC and State University of New York, Stony Brook. The National Institutes of Health Funded this research.

Source: UNC-Chapel Hill

Original Study DOI: 10.1002/jbmr.3159

Exercise can even burn off fat in bone marrow - Futurity  https://www.futurity.org/bone-marrow-fat-exercise-1435062-2/