Dapagliflozin, a Sodium-Glucose Co-Transporter 2 Inhibitor, Acutely Reduces Energy Expenditure in BAT via Neural Signals in Mice

Abstract

Selective sodium glucose cotransporter-2 inhibitor (SGLT2i) treatment promotes urinary glucose excretion, thereby reducing blood glucose as well as body weight. However, only limited body weight reductions are achieved with SGLT2i treatment. Hyperphagia is reportedly one of the causes of this limited weight loss. However, the effects of SGLT2i treatment on systemic energy expenditure have not been fully elucidated. Herein, we investigated the acute effects of dapagliflozin, a SGLT2i, on systemic energy expenditure in mice. Eighteen hours after dapagliflozin treatment oxygen consumption and brown adipose tissue (BAT) expression of ucp1, a thermogenesis-related gene, were significantly decreased as compared to those after vehicle treatment. In addition, dapagliflozin significantly suppressed norepinephrine (NE) turnover in BAT and c-fos expression in the rostral raphe pallidus nucleus (rRPa) which contains the sympathetic premotor neurons responsible for thermogenesis. These findings indicate that the dapagliflozin-mediated acute decrease in energy expenditure involves a reduction in BAT thermogenesis via decreased sympathetic nerve activity from the rRPa. Furthermore, common hepatic branch vagotomy abolished the reductions in ucp1 expression and NE contents in BAT and c-fos expression in the rRPa. In addition, alterations in hepatic carbohydrate metabolism, such as decreases in glycogen contents and upregulation of phosphoenolpyruvate carboxykinase, manifested prior to the suppression of BAT thermogenesis, e.g. 6 hours after dapagliflozin treatment. Collectively, these results suggest that SGLT2i treatment acutely suppresses energy expenditure in BAT via regulation of an inter-organ neural network consisting of the common hepatic vagal branch and sympathetic nerves.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Administration of dapagliflozin increased UGE and reduced blood glucose levels.

Timeline of study design (A). Urinary glucose (B) and plasma blood glucose (C) after a single oral dose of dapagliflozin (10mg/kg). Plasma insulin (D), body weight (BW) (E), WAT weight (F) and plasma NEFA (G) in SGLT2i- and control-mice. Values shown are means ±SEM (n = 6–7 per group). Significance as compared to control-mice is indicated (**P

Fig 2. Dapagliflozin acutely suppressed BAT thermogenesis by reducing sympathetic nerve activity.

Oxygen consumption during the 18 hours following dapagliflozin administration (A). Respiratory exchange rate (RER) during the 18 hours following dapagliflozin administration (B). Relative amounts of UCP1 (C) and PGC1α (D) mRNA in BAT. BAT (E) and rectal (F) temperatures 18 hours after dapagliflozin administration. NE turnover in BAT 18 hours after dapagliflozin administration (G). The difference in the NE decline between SGLT2i- and control-mice due to α-methyl-p-tyrosine (α-MT) treatment was statistically analyzed employing two-way ANOVA. Coronal section of the rostral ventromedial medulla before (upper panel) and after (lower panel) microdissection of the rRPa. Py, pyramidal tract (H). Relative amounts of c-fos mRNA in the rRPa 18 hours after dapagliflozin administration (I). Immunohistochemical detection of c-fos protein in the rRPa (J). The number of c-fos positive neurons in the rRPa (K). Plasma leptin levels during the 18 hours following dapagliflozin administration (L). Plasma glucagon (M), NE (N) and epinephrine (E) (O) levels 18 hours after dapagliflozin administration. Values shown are means ±SEM (n = 6–7 per group). Significance as compared to control-mice is indicated (**P < 0.01 and *P < 0.05 and). ND = not detectable.

Fig 3. Dapagliflozin enhances hepatic gluconeogenesis and glycogenolysis.

Hepatic glycogen accumulation (A), and histological findings with periodic acid-Schiff (PAS) staining of the liver 6 hours after dapagliflozin administration (B). Relative amounts of G6Pase (C) and PEPCK (D) mRNA in the liver. Values shown are means ±SEM (n = 5–7 per group). Significance as compared to control-mice is indicated (**P

Fig 4. Common hepatic branch vagotomy attenuated suppression of BAT thermogenesis induced by dapagliflozin administration.

Plasma blood glucose (A) and BW (B) after dapagliflozin administration (n = 6–7 per group). Significance is indicated **(P