Role of the CRH system in the regulation of energy balance

The corticotropin-releasing hormone (CRH) system has emerged in recent years as one of the neuronal systems most susceptible of pla)ring a genuine role in the regulation of energy balance, The CRH system whose most recognized action is the control of the pituitary-adrenal axis, has also been implicated in the control of food intake and energy expenditure. CRH has been reported to be involved in the anorectic effects of treadmill running, restraint stress, estradiol, and caffeine, as well as in the thermogenic actions of serotoninergic agonists and some cytokines. It appears more and more evident that some of the various components of the CRH system could be sites of action for leptin, insulin and corticosteroids, three hormones whose plasma variations could signal the brain as to the status of energy reserves. Finally, evidence is accumulating which suggests that the tone of the CRH system could be reduced in obesity and perhaps more generally in conditions promoting energy deposition. Indeed, recent data have shown chat both obesity and food deprivation could reduce the levels of the CRH type 2 receptor in the ventromedial hypothalamic nucleus and increase the expression of the CRH-binding protein in the preoptic area, two adaptations susceptible of reducing the activity of the CRH system.