CD38 and obesity due to melanocortin 4 receptor deficiency: The latest mechanistic data show that SFA activate the salvage pathway for NAD+ in astrocytes (NAMPT–NAD+–CD38); inhibition of CD38 suppresses hypothalamic inflammation and alleviates obesity in HFD-fed mice, establishing the NAMPT–NAD+–CD38 axis as an important regulator of astrocyte reactivity under fat excess [89].