Sweet enhancing effect of ANG II is mediated by CB1
Endocannabinoids such as anandamide [N-arachidonoylethanolamine (AEA)] and 2-arachidonoyl glycerol (2-AG) are known as orexigenic mediators that act via cannabinoid receptor 1 (CB1) in the hypothalamus and limbic forebrain to induce appetite and stimulate food intake 79 and 80. It is also shown that endocannabinoids enhance sweet taste sensitivity of T1r3 positive taste cells via CB1 [52]. Moreover, It is reported that CB1 is transactivated by AT1 in Chinese hamster ovary cells [81], or significant up-regulation of AT1-CB1 heteromers and enhancement of ANG II-mediated signalling as compared with control [82]. These results raised the possibility that the transactivation of CB1 by AT1 in sweet taste cells would enhance sweet taste sensitivity by administration of ANG II. To assess this possibility, the effects of ANG II on taste responses were examined using CB1-knockout (KO) mice [83]. As observed in B6 control mice, the CT nerve responses to NaCl in CB1-KO mice were significantly decreased after administration of ANG II. However, ANG II had no effect on responses to sweeteners in CB1-KO mice. These results suggest that ANG II acts to modulate sweet taste responses via CB1 receptors in T1r3 expressing sweet taste cells independently of αENaC expressing taste cells [48]. The physiological significance of the sweet enhancing effect of ANG II may lead to increase calorie intake, which may play a role in regulating glucose homeostasis in addition to sodium one. This hypothesis may be supported by a study comparing the effect of the AT1 receptor blockers (e.g. valsartan, losartan) versus placebo on the development of diabetes in patients with impaired glucose tolerance and cardiovascular risk factors or disease. The incidence of diabetes was modestly but significantly lower in the valsartan-treated group compared to the placebo group [84].
เพิ่มผลของ II อ่างทองหวานเป็น mediated โดย CB1Endocannabinoids such as anandamide [N-arachidonoylethanolamine (AEA)] and 2-arachidonoyl glycerol (2-AG) are known as orexigenic mediators that act via cannabinoid receptor 1 (CB1) in the hypothalamus and limbic forebrain to induce appetite and stimulate food intake 79 and 80. It is also shown that endocannabinoids enhance sweet taste sensitivity of T1r3 positive taste cells via CB1 [52]. Moreover, It is reported that CB1 is transactivated by AT1 in Chinese hamster ovary cells [81], or significant up-regulation of AT1-CB1 heteromers and enhancement of ANG II-mediated signalling as compared with control [82]. These results raised the possibility that the transactivation of CB1 by AT1 in sweet taste cells would enhance sweet taste sensitivity by administration of ANG II. To assess this possibility, the effects of ANG II on taste responses were examined using CB1-knockout (KO) mice [83]. As observed in B6 control mice, the CT nerve responses to NaCl in CB1-KO mice were significantly decreased after administration of ANG II. However, ANG II had no effect on responses to sweeteners in CB1-KO mice. These results suggest that ANG II acts to modulate sweet taste responses via CB1 receptors in T1r3 expressing sweet taste cells independently of αENaC expressing taste cells [48]. The physiological significance of the sweet enhancing effect of ANG II may lead to increase calorie intake, which may play a role in regulating glucose homeostasis in addition to sodium one. This hypothesis may be supported by a study comparing the effect of the AT1 receptor blockers (e.g. valsartan, losartan) versus placebo on the development of diabetes in patients with impaired glucose tolerance and cardiovascular risk factors or disease. The incidence of diabetes was modestly but significantly lower in the valsartan-treated group compared to the placebo group [84].
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