Figure 1. Hypothalamus has a LAT1-dependent amino acid uptake system that is altered by metabolic states.

(A) Schematic diagram of the procedure for [¹²⁵I]IMT uptake assay. (B and C) Brain tissues from wild-type mice at 8–12 weeks of age were incubated with [¹²⁵I]IMT at 4°C or 37°C for 30 minutes in Hanks’ balanced salt solution (HBSS) buffer (B) (n = 5, ***P < 0.001, 2-tailed Student’s t test) or at 37°C for 30 minutes in HBSS buffer containing 30 μM JPH203 (C) (n = 10 or 11, ***P < 0.001, 2-tailed Student’s t test). (D and E) Quantification of mRNAs encoding LAT family in VMH (D) and ARC (E) of mice fed a normal chow diet (NC) at 8–12 weeks of age (n = 4, *P < 0.05, **P < 0.01, Kruskal-Wallis test post hoc Dunn’s test). TPM, transcripts per million. (F) Quantification of mRNAs encoding LAT family in human hypothalamus (n = 202, ***P < 0.001, Kruskal-Wallis test post hoc Dunn’s test). (G) Brain tissues from WT mice fed an NC or HFD (for 17 weeks, from 7 to 24 weeks of age) at 24 weeks of age were incubated with [¹²⁵I]IMT at 37°C for 30 minutes in HBSS buffer (n = 5, *P < 0.05, 2-tailed Student’s t test). (H) Brain tissues from WT mice and db/db mice at 24 weeks of age were incubated with [¹²⁵I]IMT at 37°C for 30 minutes in HBSS buffer (n = 5, ***P < 0.001, 2-tailed Student’s t test). (I) LAT1-dependent [¹²⁵I]IMT uptake in brain tissues from WT mice and db/db mice at 24 weeks of age (n = 5, **P < 0.01, 2-tailed Student’s t test). (J and K) Quantification of Slc7a5 mRNA in VMH (J) and ARC (K) of mice fed an NC or HFD (from 5–6 to 8–12 weeks of age) at 8–12 weeks of age (n = 4, *P < 0.05, ***P < 0.001, Fisher’s exact test). All the mice used in this study were male. CPM, counts per million.