Obesity and downregulated hypothalamic leptin receptors in male metallothionein-3-null mice

► Metallothionein-3 (Mt3) null male mice develop obesity. ► The cause for obesity may involve decreased metabolic rates. ► In the hypothalamus, Mt3 null mice show reduced Lepr expression. ► Mt3 may modulate energy expenditure via modulating Lepr signaling in a hypothalamus.