Diet high in fat could potentially affect the body's internal clock in rats
In a recent study, researchers have discovered that a crucial region in the brainstem, known as the nucleus of the solitary tract (NTS), plays a significant role in the development of obesity due to high-fat diets (HFDs) [1][3].
The NTS, a key integrative center, processes visceral sensory information that influences feeding behavior and energy homeostasis, processes that are regulated by circadian rhythms and metabolic states [2]. It receives and integrates sensory inputs that affect autonomic and metabolic regulation.
Regarding its connection with circadian rhythms, high-fat diets, and obesity in humans, the NTS acts as a crucial hub for visceral sensory input that affects feeding behavior and energy homeostasis [2]. High fat diets impact the activity of brainstem and hypothalamic circuits controlling appetite and energy balance. NTS neurons receive signals reflecting metabolic state, such as hormonal cues, which are altered by high fat diets. This input influences autonomic regulation of food intake and energy expenditure, contributing to the development of obesity.
The study, conducted on rats, revealed that HFD rats initially reduced the amount they ate but still consumed more calories than the other group [6]. As the study progressed, the two groups became more divergent, with the HFD rodents increasing their nighttime food intake and later beginning to consume excess calories during the day [6]. The HFD rats also changed their feeding behavior, eating 24 hours a day and snacking during their inactive phase (daytime) [4].
Interestingly, the brainstem clock disturbances were found to be a cause, rather than a result, of obesity in HFD rats [5]. The HFD rats showed a trend toward higher body weight, but the weight gain did not occur before the changes in circadian feeding activity [6]. This suggests that the brainstem clock doesn't need the master clock in the hypothalamus to generate its rhythmicity [7].
The researchers used immunohistochemical and electrophysiological approaches to investigate these independent oscillators in more detail [7]. In the HFD rats, orexin neuron activity was reduced during the day, likely due to continued eating [7]. Although the master clock is driven primarily by exposure to light, other oscillators are influenced by food consumption.
In summary, the NTS is a robust circadian oscillator that links visceral sensory information to brain circuits controlling metabolism and circadian feeding behaviors [1][3][5]. While the NTS itself is not the primary circadian clock, it is a key integrative center that plays an important role in how high-fat diets can lead to obesity in humans. Detailed mechanistic studies in humans remain active fields of research, highlighting the NTS's integrative and modulatory roles rather than being a primary circadian regulator.
References: [1] Brainstem neuroanatomy emphasizing the NTS role in survival functions and sensory processing. [3] Vagus nerve sensory fibers converge on NTS in the medulla, essential for visceral sensory integration. [5] Hypothalamic circuits connected to metabolic regulation and feeding behavior impact NTS function in relation to diet and energy balance. [6] A new study has mapped a region of the rodent brain, the nucleus of the solitary tract, that exhibits robust day-night changes in activity and functions as a "circadian oscillator." [7] The study suggests that the brainstem clock doesn't need the master clock in the hypothalamus to generate its rhythmicity.
- The study reveals that high-fat diets can influence the activity of the brainstem and hypothalamic circuits controlling appetite and energy balance, which might contribute to the development of obesity and other nutrition-related medical conditions.
- In relation to high-fat diets and obesity, the nucleus of the solitary tract (NTS) acts as a crucial hub for visceral sensory input that affects feeding behavior and energy homeostasis, thus playing a significant role in health-and-wellness and fitness-and-exercise.
- The NTS, a key integrative center, processes visceral sensory information that influences circadian feeding activity, which might impact mental-health by altering feeding behavior and energy balance.
- Detailed mechanistic studies in humans on the NTS's integrative and modulatory roles are active fields of research, aiming to understand its effects on nutrition and overall health, including obesity and related medical conditions.
