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| Source: Vander et al.: Human Physiology: The Mechanism of Body Function, Eighth Edition. |
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it is developed a physiologically-based mathematical model for leptin. Leptin is a master hormone in the body that controls hunger and feelings of satiety, however it is a key hormone for controlling metabolism regarding energy expenditure. Leptin is secreted mainly by adipose (fat) tissue, white tissues, so the more overweight a person is, typically, the higher his leptin levels. Leptin does not change just with fat mass, other factors can influence.
In the following scheme we can see the interplay between adipocytes, brain (mainly hypothalamus), and the central nervous system. In essence, the higher the fat tissue mass, the more it is produced leptin, the central nervous system is activated meaning that we have energy on board. This loop might seem unstable, but it can reach equilibrium from two perspectives: when eating balance energy expenditure or when other hormones interferes such as insulin or ghrelin.
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The hormonal control system created by leptin.
Source: Youtube, 2014. |
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| Source: Youtube, 2014. |
Energy Homeostasis, or energy balance, is an aspect of bioenergetics concerning
the energy flow through living systems; metabolic regulation in human terms covers the means by which we take in nutrients in discrete meals, and deliver energy as required, varying from moment to moment and from tissue to tissue, in a pattern which may have no relationship at all to the pattern of intake, by metabolism Frayn (2010). Energy homeostasis
involves the human body using chemical and neural signals to adjust the amount
of energy flows; and to regulate caloric intake by signaling the brain to
regulate the sensation of hunger.
"This controversy underscores the
fact that, despite the impressive progress made over the past few decades in
unraveling many of the molecular pathways involved in energy regulation, we still
have a rather murky understanding of
how all the pieces fit together to function as an integrated system. Most previous mathematical models
of metabolic energy regulation have not explicitly modeled the neuroendocrine
feedback system that maintains energy
homeostasis. In order to address this
deficiency, we have developed a mathematical model that simulates the
physiological system that regulates energy
metabolism."
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Simulation deficient-leptin mouse against a normal one.
Source: own work. |
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Simulation of a food-control.
Source: own work. |
Paper reviewed:
Tam, J.; Fukumura,
D.; Jain, R. K.; A mathematical model of
murine metabolic regulation by leptin: energy balance and defense of a stable
body weight. Cell Metab. 2009 January 7; 9(1): 52–63. doi:10.1016/j.cmet.2008.11.005.
Further
Uluseker,
C.; Mathematical Model for Leptin Dynamics. Master
of Science Thesis, MathMods Erasmus Mundus M.Sc. Programme, Mathematical
Models in Life and Social Sciences. Department
of Information Engineering, Computer Science and Mathematics. University of L'Aquila:
Italy:
2014.
Carla Eduarda Machado Romero; Angelina Zanesco. O papel dos hormônios leptina e grelina na gênese da obesidade. Rev. Nutr. vol.19 no.1 Campinas Jan./Feb. 2006.
References mentioned
Keith N. Frayn, Metabolic Regulation A Human Perspective. Third Edition. wiley-blackwell, 2010.
