Neurosecretory Protein GL, a Hypothalamic Small Secretory Protein, Participates in Energy Homeostasis in Male Mice

Abstract

We have recently identified from the avian hypothalamus a complementary DNA encoding a small secretory protein termed neurosecretory protein GL (NPGL). In chicks, NPGL increases body weight gain without affecting food intake. A database search reveals that NPGL is conserved throughout vertebrates. However, the central distribution and functional role of NPGL remains to be elucidated in mammals. In this study, we identified the precursor complementary DNA encoding NPGL from the mouse hypothalamus. Quantitative reverse transcription polymerase chain reaction and morphological analyses revealed that NPGL precursor messenger RNA is robustly expressed in the mediobasal hypothalamus with NPGL neurons specifically localized to the lateroposterior part of the arcuate nucleus in the hypothalamus. NPGL-immunoreactive fibers were observed in close anatomical contact with pro-opiomelanocortin neurons in the rostral region of the arcuate nucleus. NPGL messenger RNA expression was elevated by 24-hour fasting and reduced by feeding of a high-fat diet for 5 weeks. Furthermore, intracerebroventricular injection of mature NPGL increased food intake, pointing to an important role in feeding. Taken together, these findings report on the distribution of NPGL in the mammalian brain and point to an important role for this neuropeptide in energy homeostasis.