HYPOTHALAMIC-LESIONS INCREASE LEVELS OF NEUROPEPTIDE-Y MESSENGER-RNA IN THE ARCUATE NUCLEUS OF MICE

A recent study demonstrated that hypothalamic lesions induced by goldt hioglucose (GTG) in mice produced an increase in neuronal immunoreacti vity for neuropeptide Y (NPY) in the hypothalamic arcuate nucleus. Sin ce NPY is a potent stimulator of feeding, this increase represented a potential explanation for the hyperphagia seen after GTG lesions. To e xamine whether or not this increase in NPY immunoreactivity was accomp anied by an increase in the mRNA for NPY, in situ hybridization histoc hemistry for NPY mRNA in control and in lesioned mice was performed. A 47% increase in NPY mRNA levels in the arcuate nucleus was observed i n lesioned mice compared with controls, suggesting that an increased e xpression of the gene for NPY contributes to elevations in hypothalami c NPY after lesioning. This elevation in NPY may, in turn, relate to m echanisms provoking hyperphagia.