Stereotaxic Viral Injections in Mice

Stereotaxic injections were performed as previously described (Krashes et al., 2013 (link)). Mice were anesthetized with isoflurane and placed into a stereotaxic apparatus (Stoelting Just for Mice). For postoperative care, mice were injected intraperitoneally with meloxicam (0.5 mg per kg). After exposing the skull via small incision, a small hole was drilled for injection. A pulled-glass pipette with 20–40 mm tip diameter was inserted into the brain and virus was injected by an air pressure system. A micromanipulator (Grass Technologies, Model S48 Stimulator) was used to control injection speed at 25 nl min⁻¹ and the pipette was withdrawn 5 min after injection. AAV10-CAG-FLEX-ChR2(H134R)-tdTomato (University of Pennsylvania School of Medicine; titer 1.3 × 10¹³ genome copies per ml) was unilaterally injected into the arcuate nucleus of the hypothalamus (ARC; 200–300 nl, bregma: AP: –1.44 mm, DV: −5.70 mm, ML: ±0.25 mm).