Submitted to: Biochemical and Biophysical Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2002
Publication Date: 11/1/2002
Citation: Czaja, K., Lakomy, M., Sienkiewicz, W., Kaleczyc, J., Pidsudko, Z., Barb, C.R., Rampacek, G.B., Kraeling, R.R. 2002. Distribution of neurons containing leptin receptors in the hypothalamus of the pig. Biochemical and Biophysical Research Communications. Interpretive Summary: Adipose tissue is no longer considered as only a depot to store excess energy in the form of fat. Numerous biologically active substances, which affect appetite, growth and reproduction are produced by adipose tissue. Thus, adipose tissue can be viewed as an endocrine organ. The recently discovered protein, leptin, is secreted by fat tissue and serves as a circulating signal of nutritional status and regulates body weight, energy expenditure, growth and reproduction through a central nervous system action, but specific anatomical sites and pathways responsible for mediating these effects are still unclear. In collaboration with scientists at the University of Warmia and Mazury in Olsztyn, Poland, ARS scientists at the Richard B. Russell Agricultural Research Center systematically examined distribution of neurons containing leptin receptor in the porcine hypothalamus by means of immunohistochemical staining methods. Findings indicate that there are distinct neuronal populations containing leptin receptors in areas of the porcine hypothalamus which are associated with regulation of feeding behavior and neuroendocrine activity. Therefore, understanding the specific anatomical sites and neural pathways by which leptin acts is the foundation for developing new methods to promote efficient growth and accelerate puberty.
Technical Abstract: Leptin, secreted by white adipocytes, has profound feeding, metabolic and neuroendocrine effects. Leptin acts on the brain, but specific anatomical sites and pathways responsible for mediating these effects are still unclear. We have systematically examined the distribution of leptin receptor containing neurons in the porcine hypothalamus by means of immunohistochemical staining methods. Leptin receptor immunoreactivity (OBR-IR) was observed in both the preoptic area and anterior hypothalamic area. No immunoreactive structures were found in the median eminence. Only single, small neurons were observed in the arcuate nucleus. The most abundant OBR-IR cell bodies were located in the supraoptic nucleus. In the paraventricular nucleus, OBR-IR neurons were moderate in number. Single, dispersed neurons were found in the ventromedial nucleus. These findings indicate that there are distinct OBR-IR neuronal populations in the porcine hypothalamus and leptin not only plays an integrative role in feeding behavior, but also in neuroendocrine activity.