Npy egfp

Cre recombinase was targeted to parvalbumin (Gene ID: 19293) expressing cells of the GP and striatum using transgenic knock-in mice that link Cre expression to the parvalbumin locus with an internal ribosome entry site (PV^i-Cre). PV^i-Cre were generated by the Arber lab [45 (link)] and obtained from the Jackson Labs (stock # 008069). Both PV^i-Cre/+ and PV^{i-Cre/ i-Cre} mice were used for experiments. To visualize the full processes of Cre expressing cells, Cre mice were bred to Cre-dependent tdTomato reporter allele (Ai14; Jackson Labs, stock # 007914; referred to as Rosa26^lsl-tdTomato). Striatal cell types were identified by a combination of neuronal morphology and molecular markers, including bacterial artificial chromosome (BAC) transgenes expressing EGFP under the control of the dopamine 2 receptor (Drd2-EGFP; GENSAT founder line S118) and Neuropeptide Y (NPY-EGFP; Jackson Labs, stock # 006417) regulatory sequence. Despite some differences in strains of origin, all transgenic mice were maintained on a predominantly C57BL/6 background. All wild-type mice were C57BL/6 and obtained from Charles River. All experimental manipulations were performed in accordance with protocols approved by the Harvard Standing Committee on Animal Care following guidelines described in the US National Institutes of Health Guide for the Care and Use of Laboratory Animals.

All rodent studies were approved by and performed according to the guidelines of the Institutional Animal Care and Use Committee of the Helmholtz Center Munich, Germany; the University of Cincinnati; or the Augusta University, USA. Wild-type male mice (C57BL/6JRj) were purchased from Janvier (Le Genest-Saint-Isle, France); POMC^eGFP (Stock No: 009593) and NPY^eGFP (Stock No: 006417) male mice were purchased from Jackson Laboratory (Bar Harbor, ME, USA) with the C57BL/6 genetic background. Ten-week-old male Wistar rats were purchased from Charles River (Sulzfeld, Germany). All mice and rats were group housed on a 12 h light, 12 h dark cycle (light from 7:00 to 19:00) at 22 °C, with free access to standard chow diet (LM-485, Teklad) and water before experiments. DIO was induced by HCHF diet purchased from Research Diets (D12331, Research Diets Inc., New Brunswick, NJ, USA). HCHF diet feeding was started at week 8 of age. Body weight and food intake were monitored according to each experimental design. Mice were single-housed after receiving stereotaxic infusions or brain surgeries.