COEXPRESSION OF LEPTIN RECEPTOR AND PREPRONEUROPEPTIDE-Y MESSENGER-RNA IN ARCUATE NUCLEUS OF MOUSE HYPOTHALAMUS

Leptin, the protein product of the adipose tissue-specific ob (obese) gene (1), reduces the body weight, adiposity and food intake of obese ob/ob mice on peripheral or central injection (2, 3, 4), [I-125]leptin binding has been detected in mouse choroid plexus (5), from which a l eptin receptor gene was expression cloned (5). The gene has at least 6 splice variants (6, 7), Leptin receptor mRNA was localized in the hyp othalamus by in situ hybridization being particularly abundantly expre ssed in the arcuate nucleus (8), There is evidence linking the physiol ogical effects of injected leptin with hypothalamic neuropeptide Y (9, 10) (NPY), which has potent central effects on food intake and energy balance (11), and is also expressed in the arcuate nucleus. Here we r eport dual in situ hybridization studies for leptin receptor and NPY g ene expression in the mouse arcuate nucleus, where the majority of cel ls examined expressed both genes. This provides the first direct evide nce that leptin acts on cells that express NPY mRNA.