Growth factors, feeding regulation and the nervous system

A variety of growth factors and their receptors are present in the nervous system. Growth factors can modulate specific nervous system functions others than those related to growth, development, and tissue repair. The presence of growth factors in the brain and cerebrospinal fluid is the result of local synthesis (by neuronal, glial, vascular, and mononuclear phagocyte components), and uptake from the peripheral blood through the blood-brain barrier (in specific cases) and circumventricular organs. This paper focuses on the effects of a heterogeneous group of growth factors (acidic and basic fibroblast growth factors, insulin-like growth factors, epidermal growth factor, platelet-derived growth factor, interleukin-1 and others) on the central nervous system (CNS), in particular, on feeding regulation. Recent evidence supporting participation of growth factors in the regulation of feeding by a direct action at the level of the CNS is reviewed. Various growth factors have the ability to suppress short- and long-term food intake (FI), whereas others affect only short-term FI, or do not affect FI. Acute and chronic pathological processes stimulate the synthesis and release of growth factors in various cellular systems, and monitoring of growth factors by the CNS could be part of the regulatory signals that induce FI suppression frequently accompanying acute and chronic disease. Thus, it is proposed that a system regulating FI through growth factor-dependent mechanisms may be operative during specific physiological or pathological conditions.