Dietary fat intake effects on mice
MC4R Neuron-specific OPA1 knockout mice were free fed soybean oil to examine its effect.
Image Credit: Osaka Metropolitan University
Scientific Frontline: Extended "At a Glance" Summary: Mitochondrial Protein OPA1 and Dietary Fat Intake
The Core Concept: Optic atrophy-1 (OPA1) is a mitochondrial fusion protein found in hypothalamic MC4R neurons that plays a critical role in regulating appetite and body weight in response to dietary fat intake.
Key Distinction/Mechanism: While high-fat food consumption is often viewed as a digestive or willpower issue, this research highlights its neurological basis, demonstrating that the presence and function of OPA1 in specific brain neurons directly influence the drive to consume fat and the resulting weight gain, with distinct variations between sexes.
Major Frameworks/Components:
- OPA1 Protein: A mitochondrial fusion protein essential for maintaining mitochondrial function and energy metabolism in neurons.
- MC4R Neurons: Hypothalamic neurons involved in appetite control.
- Sex-Specific Responses: Soybean oil intake increased OPA1 expression in male wild-type mice, but not in females.
- Impact of OPA1 Deficiency: Mice lacking OPA1 in MC4R neurons exhibited increased food intake, greater consumption of dietary fat (soybean oil), age-related weight gain, and obesity, with more pronounced effects in females.
- Setmelanotide Efficacy: The appetite-suppressing effect of the anti-obesity drug setmelanotide (an MC4R agonist) was significantly reduced in OPA1-deficient female mice, though it remained effective in males.
Branch of Science: Neuroscience, Cellular Biology, Endocrinology.
Future Application: The development of targeted, personalized obesity treatments and medications that account for sex-specific neurological responses and energy metabolism in the brain.
Why It Matters: Obesity is a global health crisis linked to numerous metabolic disorders. Understanding the precise neural mechanisms that drive high-fat food consumption provides crucial insights for treating obesity at its neurological source, rather than just treating the symptoms.
Obesity is a global health concern that can contribute to diabetes, cardiovascular disease, and other metabolic disorders. Though many health conditions can lead to obesity, an increasingly worrying cause is found right on grocery store shelves: high-fat foods. These foods are notoriously difficult to resist and can promote overeating. While many mistake this for a gastrointestinal issue, research demonstrates that appetite regulation is neurologically based. Despite this knowledge, the neural mechanisms linking dietary fat intake to the regulation of appetite and body weight remain unclear.
Building on this premise, a research group led by Professor Shigenobu Matsumura of Osaka Metropolitan University’s Graduate School of Human Life and Ecology investigated the role of optic atrophy 1 (OPA1), a mitochondrial fusion protein located in hypothalamic MC4R neurons that helps maintain mitochondrial function and energy metabolism. Using wild-type and MC4R neuron–specific OPA1-knockout mice, the team examined the regulatory effects of OPA1 on appetite control and body weight via the ad libitum feeding of soybean oil as a dietary fat source.
The researchers found that soybean oil increased OPA1 expression in wild-type male mice, but not in females. Mice lacking OPA1 exhibited increased food intake, age-related weight gain, and the development of obesity. When given ad libitum access to both standard chow and soybean oil, the mice consumed more fat and gained weight, with these effects being particularly pronounced in females.
The team also examined the effects of setmelanotide, an anti-obesity MC4R agonist. While the drug effectively suppressed appetite in both control and OPA1-deficient male mice, its appetite-suppressing effect was significantly reduced in OPA1-deficient females.
“Our findings provide key insights into the mechanisms underlying obesity from the perspective of neuronal energy metabolism,” said Professor Matsumura. “The sex differences observed in OPA1 responses and obesity susceptibility may help inform the development of obesity treatments that account for these variations, as well as future personalized medicine approaches.”
Funding: This study was supported by the Public Foundation of Tojuro Iijima Foundation for Food Science and Technology and JSPS KAKENHI (grant numbers 23H02164 and 26K01702).
Disclaimer: The funding bodies had no role in the study design; the collection, analysis, and interpretation of data; the writing of the report; or the decision to submit the paper for publication.
Published in journal: FASEB Journal
Title: OPA1 in MC4R Neurons Regulates Dietary Fat Intake and Body Weight in Mice
Authors: Shigenobu Matsumura, Mizuki Fujiwara, Soyoka Horie, Miona Marutani, Eri Nousou, Nanase Iki, Yuka Yamato, Yui Otonashi, Tsutomu Sasaki, Mina Fujitani, and Teppei Fujikawa
Source/Credit: Osaka Metropolitan University
Edited by: Scientific Frontline
Reference Number: ns081626_01
