Figure 3 – Neither extended fasting nor oral glucose challenge worsens glucose tolerance in Trem2−/− mice.

Male Trem2−/− and WT mice were fed HFD diet for 16 weeks. A) ipGTT was performed after 6 and 12 weeks on HFD diet after a 5h fast. Another ipGTT was conducted at 16 weeks on HFD diet after a 15 h fast. B) Fasting glucose, NEFA, and C) plasma insulin concentrations were measured throughout diet feeding after either a 5 h of 15 h fast. D) oral glucose tolerance test (OGTT) was performed in male and female mice after 12 weeks on HFD diet and a 5 h fast. E) Insulin tolerance test (ITT) was performed after 10 weeks of HFD feeding in WT versus Trem2−/− mice. Following a 4 h fast and basleine glucose measurement, insulin was injected i.p. (0.75 U/kg body weight) and glucose readings were collected frequently for 30 minutes. F) Insulin and glycerol response to a glucose challenge. After 8 weeks of HFD, mice were fasted for 5 h and gavaged with glucose (3.5g/kg FFM) to determine physiological suppression of plasma glycerol (a proxy for lipolysis). Blood was sampled from a carotid artery catheter. Two way repeated measures ANOVA with time and genotype as factors were conducted for panels A, B, C, and D (n=6–9/condition). Multiple comparisons were assessed using Tukey post hoc testing. Two-way ANOVA with genotype and sex as factors was conducted for panel E with Tukey adjusted pairwise comparisons (n=6–8/group). In panels A, B, and C Trem2−/− mice were purchased directly from JAX and age-matched C57BL/6J mice were used as controls. Blood was collected from the tail for these experiments. Animal housing and experiments were conducted at room temperature (21–23°C). In panels D-F, mice are littermates. Graphics were generated using BioRender.com. Data are presented as mean ± SD. HFD< high fat diet; OGTT, oral glucose tolerance test; FFM, fat free mass. *p<0.05, **p<0.01