RESUMO
Dynamic changes in adipose tissue blood flow (ATBF) with nutritional status play a role in the regulation of metabolic and endocrine functions. Activation of the sympathetic nervous system via β-adrenergic receptors (β-AR) contributes to the control of postprandial enhancement of ATBF. Herein, we sought to identify the role of each β-AR subtype in the regulation of ATBF in mice. We monitored the changes in visceral epididymal ATBF (VAT BF), induced by local infusion of dobutamine, salbutamol, and CL316,243 (a selective β1-, β2-, and β3-AR agonist, respectively) into VAT of lean CD-1 mice and global adipose triglyceride lipase (ATGL) knockout (KO) mice, using laser Doppler flowmetry. Administration of CL316,243, known to promote lipolysis in adipocytes, significantly increased VAT BF of CD-1 mice to a greater extent compared to that of the vehicle, whereas administration of dobutamine or salbutamol did not produce significant differences in VAT BF. The increase in VAT BF induced by β3-AR stimulation disappeared in ATGL KO mice as opposed to their wild-type (WT) littermates, implying a role of ATGL-mediated lipolysis in the regulation of VAT BF. Different vascular reactivities occurred despite no significant differences in vessel density and adiposity between the groups. Additionally, the expression levels of the angiogenesis-related genes were significantly higher in VAT of ATGL KO mice than in that of WT, implicating an association of ATBF responsiveness with angiogenic activity in VAT. Our findings suggest a potential role of β3-AR signaling in the regulation of VAT BF via ATGL-mediated lipolysis in mice.
RESUMO
Taste sensation is the gatekeeper for direct decisions on feeding behavior and evaluating the quality of food. Nutritious and beneficial substances such as sugars and amino acids are represented by sweet and umami tastes, respectively, whereas noxious substances and toxins by bitter or sour tastes. Essential electrolytes including Na+ and other ions are recognized by the salty taste. Gustatory information is initially generated by taste buds in the oral cavity, projected into the central nervous system, and finally processed to provide input signals for food recognition, regulation of metabolism and physiology, and higher-order brain functions such as learning and memory, emotion, and reward. Therefore, understanding the peripheral taste system is fundamental for the development of technologies to regulate the endocrine system and improve whole-body metabolism. In this review article, we introduce previous widely-accepted views on the physiology and genetics of peripheral taste cells and primary gustatory neurons, and discuss key findings from the past decade that have raised novel questions or solved previously raised questions.
RESUMO
Dynamic changes in adipose tissue blood flow (ATBF) with nutritional status play a role in the regulation of metabolic and endocrine functions. Activation of the sympathetic nervous system via β-adrenergic receptors (β-AR) contributes to the control of postprandial enhancement of ATBF. Herein, we sought to identify the role of each β-AR subtype in the regulation of ATBF in mice. We monitored the changes in visceral epididymal ATBF (VAT BF), induced by local infusion of dobutamine, salbutamol, and CL316,243 (a selective β1-, β2-, and β3-AR agonist, respectively) into VAT of lean CD-1 mice and global adipose triglyceride lipase (ATGL) knockout (KO) mice, using laser Doppler flowmetry. Administration of CL316,243, known to promote lipolysis in adipocytes, significantly increased VAT BF of CD-1 mice to a greater extent compared to that of the vehicle, whereas administration of dobutamine or salbutamol did not produce significant differences in VAT BF. The increase in VAT BF induced by β3-AR stimulation disappeared in ATGL KO mice as opposed to their wild-type (WT) littermates, implying a role of ATGL-mediated lipolysis in the regulation of VAT BF. Different vascular reactivities occurred despite no significant differences in vessel density and adiposity between the groups. Additionally, the expression levels of the angiogenesis-related genes were significantly higher in VAT of ATGL KO mice than in that of WT, implicating an association of ATBF responsiveness with angiogenic activity in VAT. Our findings suggest a potential role of β3-AR signaling in the regulation of VAT BF via ATGL-mediated lipolysis in mice.
RESUMO
Taste sensation is the gatekeeper for direct decisions on feeding behavior and evaluating the quality of food. Nutritious and beneficial substances such as sugars and amino acids are represented by sweet and umami tastes, respectively, whereas noxious substances and toxins by bitter or sour tastes. Essential electrolytes including Na+ and other ions are recognized by the salty taste. Gustatory information is initially generated by taste buds in the oral cavity, projected into the central nervous system, and finally processed to provide input signals for food recognition, regulation of metabolism and physiology, and higher-order brain functions such as learning and memory, emotion, and reward. Therefore, understanding the peripheral taste system is fundamental for the development of technologies to regulate the endocrine system and improve whole-body metabolism. In this review article, we introduce previous widely-accepted views on the physiology and genetics of peripheral taste cells and primary gustatory neurons, and discuss key findings from the past decade that have raised novel questions or solved previously raised questions.