TY - JOUR
T1 - Absence of cannabinoid 1 receptor in beta cells protects against high-fat/high-sugar diet-induced beta cell dysfunction and inflammation in murine islets
AU - González-Mariscal, Isabel
AU - Montoro, Rodrigo A.
AU - Doyle, Máire E.
AU - Liu, Qing Rong
AU - Rouse, Michael
AU - O’Connell, Jennifer F.
AU - Santa-Cruz Calvo, Sara
AU - Krzysik-Walker, Susan M.
AU - Ghosh, Soumita
AU - Carlson, Olga D.
AU - Lehrmann, Elin
AU - Zhang, Yongqing
AU - Becker, Kevin G.
AU - Chia, Chee W.
AU - Ghosh, Paritosh
AU - Egan, Josephine M.
N1 - Publisher Copyright:
© 2018, The Author(s).
PY - 2018/6/1
Y1 - 2018/6/1
N2 - Aims/hypothesis: The cannabinoid 1 receptor (CB1R) regulates insulin sensitivity and glucose metabolism in peripheral tissues. CB1R is expressed on pancreatic beta cells and is coupled to the G protein Gαi, suggesting a negative regulation of endogenous signalling in the beta cell. Deciphering the exact function of CB1R in beta cells has been confounded by the expression of this receptor on multiple tissues involved in regulating metabolism. Thus, in models of global genetic or pharmacological CB1R blockade, it is difficult to distinguish the indirect effects of improved insulin sensitivity in peripheral tissues from the direct effects of inhibiting CB1R in beta cells per se. To assess the direct contribution of beta cell CB1R to metabolism, we designed a mouse model that allows us to determine the role of CB1R specifically in beta cells in the context of whole-body metabolism. Methods: We generated a beta cell specific Cnr1 (CB1R) knockout mouse (β-CB1R−/−) to study the long-term consequences of CB1R ablation on beta cell function in adult mice. We measured beta cell function, proliferation and viability in these mice in response to a high-fat/high-sugar diet and induction of acute insulin resistance with the insulin receptor antagonist S961. Results: β-CB1R−/− mice had increased fasting (153 ± 23% increase at 10 weeks of age) and stimulated insulin secretion and increased intra-islet cAMP levels (217 ± 33% increase at 10 weeks of age), resulting in primary hyperinsulinaemia, as well as increased beta cell viability, proliferation and islet area (1.9-fold increase at 10 weeks of age). Hyperinsulinaemia led to insulin resistance, which was aggravated by a high-fat/high-sugar diet and weight gain, although beta cells maintained their insulin secretory capacity in response to glucose. Strikingly, islets from β-CB1R−/− mice were protected from diet-induced inflammation. Mechanistically, we show that this is a consequence of curtailment of oxidative stress and reduced activation of the NLRP3 inflammasome in beta cells. Conclusions/interpretation: Our data demonstrate CB1R to be a negative regulator of beta cell function and a mediator of islet inflammation under conditions of metabolic stress. Our findings point to beta cell CB1R as a therapeutic target, and broaden its potential to include anti-inflammatory effects in both major forms of diabetes. Data availability: Microarray data have been deposited at GEO (GSE102027).
AB - Aims/hypothesis: The cannabinoid 1 receptor (CB1R) regulates insulin sensitivity and glucose metabolism in peripheral tissues. CB1R is expressed on pancreatic beta cells and is coupled to the G protein Gαi, suggesting a negative regulation of endogenous signalling in the beta cell. Deciphering the exact function of CB1R in beta cells has been confounded by the expression of this receptor on multiple tissues involved in regulating metabolism. Thus, in models of global genetic or pharmacological CB1R blockade, it is difficult to distinguish the indirect effects of improved insulin sensitivity in peripheral tissues from the direct effects of inhibiting CB1R in beta cells per se. To assess the direct contribution of beta cell CB1R to metabolism, we designed a mouse model that allows us to determine the role of CB1R specifically in beta cells in the context of whole-body metabolism. Methods: We generated a beta cell specific Cnr1 (CB1R) knockout mouse (β-CB1R−/−) to study the long-term consequences of CB1R ablation on beta cell function in adult mice. We measured beta cell function, proliferation and viability in these mice in response to a high-fat/high-sugar diet and induction of acute insulin resistance with the insulin receptor antagonist S961. Results: β-CB1R−/− mice had increased fasting (153 ± 23% increase at 10 weeks of age) and stimulated insulin secretion and increased intra-islet cAMP levels (217 ± 33% increase at 10 weeks of age), resulting in primary hyperinsulinaemia, as well as increased beta cell viability, proliferation and islet area (1.9-fold increase at 10 weeks of age). Hyperinsulinaemia led to insulin resistance, which was aggravated by a high-fat/high-sugar diet and weight gain, although beta cells maintained their insulin secretory capacity in response to glucose. Strikingly, islets from β-CB1R−/− mice were protected from diet-induced inflammation. Mechanistically, we show that this is a consequence of curtailment of oxidative stress and reduced activation of the NLRP3 inflammasome in beta cells. Conclusions/interpretation: Our data demonstrate CB1R to be a negative regulator of beta cell function and a mediator of islet inflammation under conditions of metabolic stress. Our findings point to beta cell CB1R as a therapeutic target, and broaden its potential to include anti-inflammatory effects in both major forms of diabetes. Data availability: Microarray data have been deposited at GEO (GSE102027).
KW - Beta cell
KW - Beta cell proliferation
KW - Beta cell viability
KW - Cannabinoid 1 receptor
KW - Diabetes
KW - Inflammation
KW - Insulin
KW - Insulin resistance
KW - Islet of Langerhans
KW - Mouse
UR - http://www.scopus.com/inward/record.url?scp=85044948957&partnerID=8YFLogxK
U2 - 10.1007/s00125-018-4576-4
DO - 10.1007/s00125-018-4576-4
M3 - Article
C2 - 29497784
AN - SCOPUS:85044948957
SN - 0012-186X
VL - 61
SP - 1470
EP - 1483
JO - Diabetologia
JF - Diabetologia
IS - 6
ER -