GDF15 Injection at Standard and Thermoneutral Housing Temperatures.

For mouse studies 1 and 2 (MS1 and MS2), human recombinant GDF15 (Cat# 4570, BioVision Inc.) was prepared in saline and administered via subcutaneous (s.c.) injection as a single dose in the morning (9 AM). For mouse studies, 12 to 14 human recombinant GDF15 (Cat# Qk017, Qkine) was administrated via s.c. injection as a single dose in the morning (9 AM). At 1 h and/or 4 h posthuman recombinant GDF15 treatment, mice were killed by CO₂ inhalation and blood was collected via cardiac puncture. Blood was collected in EDTA tubes (Becton Dickinson and Company) and centrifuged to collect plasma, which was stored at −80 °C until analysis. For MS1 and MS2, plasma human GDF15 was measured using the human GDF15 Quantikine ELISA (R&D Systems) and plasma mouse corticosterone was measured using the mouse corticosterone ELISA (Cat# 55-CORMS-E01, ALPCO) as per manufacturer instructions. For MS12 to MS14, GDF15 was measured using the human GDF15 ELISA (Cat#DY957, R&D Systems, BioTechne) and plasma mouse corticosterone was measured using the mouse corticosterone EIA (Cat# AC14F1, IDS). Plasma leptin was measured using a Meso Scale Discovery two-plex mouse metabolic immunoassay kit (Cat# K15124C, Meso Scale Diagnostics).