Led driver

For bulk calcium imaging, we used a Doric Lenses fibre photometry system. In the experiment, 465 nm and 405 nm LED light sources (Doric LED driver) were delivered continuously through a rotary joint (Doric Lenses, FRJ_1×1_PT-400/430/LWMJ-0.57_1m) connected to the patch cord (Doric Lenses, MFP_400/430/1100-0.57_1m), and the GCaMP6 signal was collected back through the same fibre into the photodetector (Doric Lenses). For single-cell calcium imaging, we used nVoke (Inscopix).

For fiber photometry studies in the arcuate nucleus, the set-up of the photometry recorder^{72 (link)} consisted of an RZ5P real-time processor (Tucker-Davis Technologies) connected to a light source driver (LED Driver; Doric Lenses). The LED Driver constantly delivered excitation light at 405 nm (control) and 465 nm (NOPLight) wavelengths. The light sources were filtered by a four-port fluorescence minicube (FMC_AE(405)_E1(460–490)_F1(500–550)_S, Doric Lenses) before reaching the animal. The fluorescence signals were collected from the same fiber using a photoreceiver (Model 2151, New Focus), sent back to the RZ5P processor, and gathered by Synapse software (v.95–43718P, Tucker-Davis Technologies).

Fibre photometry was performed using an RZ5P real-time processor (Tucker-Davis Technologies). RZ5P outputs were connected to an LED Driver (Doric Lenses) for external modulation of the light sources. Light from connected 405-nm (isosbestic control) and 465-nm (GCaMP6) light-emitting diodes (P/N CLED_405, P/N CLED_465) was passed through a four-port fluorescence minicube (FMC_AE(405)_E1(460-490)_F1(500-550)_S, Doric Lenses) and collected with a photoreceiver (Model 2151, New Focus).
A fibre optic cable was attached to the implanted fibre optic canula. IR^mKate2 AgRP^GCaMP6 and IR^∆Tan AgRP^GCaMP6 mouse groups were acclimatized to the set-up 3 weeks post surgery and 1 week before recordings. For the measurement, mice were placed in a regular type 2 cage at room temperature. Water and food were removed during the recordings and introduced only if the experimental settings allowed. The location of the fibre tip was identified post hoc using histology. Mice with missed injections or wrong fibre placement were excluded from the analysis.