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The high prevalence of obesity is associated with increased mortality because of various comorbidities evoked by an increase in adiposity. Type II diabetes and cardiovascular disease are major medical conditions commonly linked to alterations in the homeostatic pathways that regulate energy homeostasis. As a master regulator of energy balance, the brain integrates peripheral signals and, in turn, modulates feeding behavior and the activity of the autonomic nervous system. The hypothalamus acts as the main hub that receives and integrates peripheral signals.

Mohamed Rouabhi, Deng-Fu Guo, Donald A. Morgan, Zhiyong Zhu, ... Kamal Rahmouni

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BBSome ablation in SF1 neurons causes obesity without comorbidities

Mohamed Rouabhi, Deng-Fu Guo, Donald A. Morgan, Zhiyong Zhu, ... Kamal Rahmouni

Objectives

The hypothalamic ventromedial nucleus (VMH) plays a major role in metabolic control, but the molecular mechanisms involved remain poorly defined. We analyzed the relevance of the BBSome, a protein complex composed of 8 Bardet–Biedl syndrome (BBS) proteins including BBS1, in VMH steroidogenic factor 1 (SF1) neurons for the control of energy homeostasis and related physiological processes.

Methods

We generated mice bearing selective BBSome disruption, through Bbs1 gene deletion, in SF1 neurons (SF1Cre/Bbs1fl/fl). We analyzed the consequence on body weight, glucose homeostasis, and cardiovascular autonomic function of BBSome loss in SF1 neurons.

Results

SF1Cre/Bbs1fl/fl mice had increased body weight and adiposity under normal chow conditions. Food intake, energy absorption, and digestive efficiency were not altered by Bbs1 gene deletion in SF1 neurons. SF1Cre/Bbs1fl/fl mice exhibited lower energy expenditure, particularly during the dark cycle. Consistent with this finding, SF1Cre/Bbs1fl/fl mice displayed reduced sympathetic nerve traffic and expression of markers of thermogenesis in brown adipose tissue. SF1Cre/Bbs1fl/fl mice also had lower sympathetic nerve activity to subcutaneous white adipose tissue that was associated with a protein expression profile that promotes lipid accumulation. Notably, despite obesity and hyperinsulinemia, SF1Cre/Bbs1fl/fl mice did not exhibit significant changes in glucose metabolism, insulin sensitivity, blood pressure, and baroreflex sensitivity.

Conclusions

Our findings demonstrate that the SF1 neuron BBSome is necessary for the regulation of energy homeostasis through modulation of the activity of the sympathetic nervous system and that the SF1 neuron BBSome is required for the development of obesity-related comorbidities.

BBSome ablation in SF1 neurons causes obesity without comorbidities

Mohamed Rouabhi, Deng-Fu Guo, Donald A. Morgan, Zhiyong Zhu, ... Kamal Rahmouni

Objectives

The hypothalamic ventromedial nucleus (VMH) plays a major role in metabolic control, but the molecular mechanisms involved remain poorly defined. We analyzed the relevance of the BBSome, a protein complex composed of 8 Bardet–Biedl syndrome (BBS) proteins including BBS1, in VMH steroidogenic factor 1 (SF1) neurons for the control of energy homeostasis and related physiological processes.

Methods

We generated mice bearing selective BBSome disruption, through Bbs1 gene deletion, in SF1 neurons (SF1Cre/Bbs1fl/fl). We analyzed the consequence on body weight, glucose homeostasis, and cardiovascular autonomic function of BBSome loss in SF1 neurons.

Results

SF1Cre/Bbs1fl/fl mice had increased body weight and adiposity under normal chow conditions. Food intake, energy absorption, and digestive efficiency were not altered by Bbs1 gene deletion in SF1 neurons. SF1Cre/Bbs1fl/fl mice exhibited lower energy expenditure, particularly during the dark cycle. Consistent with this finding, SF1Cre/Bbs1fl/fl mice displayed reduced sympathetic nerve traffic and expression of markers of thermogenesis in brown adipose tissue. SF1Cre/Bbs1fl/fl mice also had lower sympathetic nerve activity to subcutaneous white adipose tissue that was associated with a protein expression profile that promotes lipid accumulation. Notably, despite obesity and hyperinsulinemia, SF1Cre/Bbs1fl/fl mice did not exhibit significant changes in glucose metabolism, insulin sensitivity, blood pressure, and baroreflex sensitivity.

Conclusions

Our findings demonstrate that the SF1 neuron BBSome is necessary for the regulation of energy homeostasis through modulation of the activity of the sympathetic nervous system and that the SF1 neuron BBSome is required for the development of obesity-related comorbidities.

The 60 Second Metabolist

In this section authors briefly report on their work recently published in Molecular Metabolism.

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