The adipose tissue: a new member of the diffuse neuroendocrine system?

Adipose tissue is a sophisticated module, consisting of adipocytes and non-adipocyte cellular elements including stromal, vascular, nerve and immune cells. There is at present evidence that sharing of ligands and their receptors constitutes a molecular language of the human's body, which is also the case for adipose tissue and hypo- thalamus-pituitary gland. Historically, Nikolai Kulchitsky's identification of the entero- chromaffin cell in 1897 formed the basis for the subsequent delineation of the diffuse neuroendocrine system (DNES) by Friedrich Feyrter in 1938. In DNES paradigm, the secretion of hormones, neuropeptides and neurotrophic factors is executed by cells disseminated throughout the body!"for example, Kulchitsky (enterochromaffin) cells, testicular Leydig cells, and hepatic stellate cells. Here we propose that the adipose tis- sue might be a new member of DNES. Today (dnes, in Bulgarian), adipose tissue is "get- ting nervous" indeed: (i) synthesizes neuropeptides, neurotrophic factors, neurotrans- mitters, hypothalamic hormones/releasing factors and their receptors, (ii) like brain expresses endocannabinoids and amyloid precursor protein and, for steroidogenesis, the enzyme aromatase (P450arom), (iii) adipocytes may originate from the neural crest cells, and (iv) adipose-derived stem cells may differentiate into neuronal cells. Further molecular profiling of adipose tissue may provide new biological insights on its neu- roendocrine potential. Overall this may frame a novel field of study, neuroadipobiol- ogy; its development and clinical application may contribute to the improvement of human's health.