Peripheral and central localization of the nesfatin-1 receptor using autoradiography in rats

Nesfatin-1 was recently identified and introduced as food intake-regulatory hormone. Soon thereafter, mounting evidence indicated a much broader role for nesfatin-1 with an involvement in the regulation of food intake, gastrointestinal motility, glucose homeostasis, blood pressure and stress. Despite the growing knowledge on the physiological regulation and functions of nesfatin-1, the receptor mediating these effects remains to be characterized. Therefore, the aim of this study was to investigate the peripheral and central localization of the nesfatin-1 receptor by autoradiography. Male Sprague-Dawley rats were used and peripheral as well as brain tissue was processed for (125)I-nesfatin-1 autoradiography. In peripheral tissues, an autoradiographic signal was observed in the gastric mucosa of corpus and antrum, in duodenum, jejunum and ileum, while no signal was detected in the colon. Preabsorption of (125)I-nesfatin-1 with non-labeled nesfatin-1 greatly diminished the autoradiographic signal in the stomach indicating specificity (-32%, p < 0.001). A displacement assay showed an effective concentration by which 50% of (125)I-nesfatin-1 bound to the receptor (EC50) in the gastric corpus of 80 pM. Moreover, autoradiography was observed in endocrine tissues including the pituitary, pancreas, adrenal gland, testis and visceral adipose tissue. In addition, also heart, skeletal muscle, lung, liver and kidney showed autoradiographic signals. In the brain, strong (125)I-nesfatin-1 autoradiography was detected in the cortex, paraventricular nucleus of the hypothalamus, area postrema, dorsal motor nucleus of the vagus nerve and cerebellum. Based on the distribution of nesfatin-1 autoradiography, nesfatin-1 is a pleiotropic hormone that is involved in the regulation of several homeostatic functions.