Submitted to: Biochemical and Biophysical Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2002
Publication Date: 5/10/2002
Citation: Czaja, K., Lakomy, M., Kaleczyc, J., Barb, C.R., Rampacek, G.B., Kraeling, R.R. 2002. Leptin receptors, npy and tyrosine hydroxylase in autonomic neurons supplying fat depots in 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, such as leptin,, which affect appetite, growth and reproduction are produced by adipose tissue. Thus, adipose tissue can be viewed as an endocrine organ. The factors that regulate fat cell function and leptin secretion are not well defined. Adipose tissue is well supplied by nerve fibers. Adipose tissue function and leptin secretion is controlled by nutrition and nervous system activity. In collaboration with scientists at the University of Warmia and Mazury in Olsztyn, Poland, ARS scientists at the Richard B. Russell Agricultural Research Center determined the immunohistochemical characteristics of peripheral neurons innervating adipose tissue in the pig. Leptin receptors were present in the nerve fibers that innervate fat tissue. These results indicate that, in addition to acting in the brain to influence appetite and pituitary gland secretion, leptin may affect peripheral tissues by acting on receptors located in the nerve fibers that innervate adipose tissue itself.
Technical Abstract: The goal of this study was to determine the immunohistochemical characteristics of peripheral adrenergic OBR- immunoreactive (OBR-IR) neurons innervating adipose tissue in the pig. The retrograde tracer, Fast Blue (FB), was injected into either the subcutaneous, perirenal or mesentery fat tissue depots of 3 male and 3 female pigs each approximately 50 kg body weight. Sections containing FB+ neurons were stained for OBR, tyrosine hydroxylase (TH) or neuropeptide Y (NPY) using a double labeling immunofluorescence method. OBR, TH and NPY immunoreactivity was present in the thoracic (T) and lumbar (L) ganglia of the sympathetic chain, as well as in the coeliac superior mesenteric ganglion (CSMG), inferior mesenteric ganglion (IMG), intermesenteric ganglia (adrenal- ADG, aorticorenal- ARG and ovarian- OG or testicular- TG ganglion). These results indicate that, in addition to neuroendocrine functions, leptin may affect peripheral tissues by acting on receptors located in sympathetic ganglion neurons.