Counterregulation of insulin by leptin as key component of autonomic regulation of body weight

Figure 5 The conceptual model of the autonomic regulation of body weight. Autonomic nervous system regulates the energy flux through the energy conserving actions of insulin that are counterbalanced by the energy expending actions of leptin to match energy intake (EI) and expenditure (EE) and maintain stable body weight (center circle). The counterbalancing is achieved by the upregulation of leptin by the glycolytic energy flux in the WAT stimulated by insulin. Leptin, in turn, inhibits insulin secretion and actions in several organs. If dieting or food scarcity cause weight loss (left arrow), energy conservation is achieved, in part, by reduced Symp activity and EE (EEm). Predominance of Parasymp actions are manifested in reduced fasting insulin and leptin concentrations, increased tissue sensitivities to insulin (Si) and leptin (Sl) along with increased sensitivity in enzymatic nutrient sensing (Se) of energy depletion. In addition, energy is conserved through reduced S activation of metabolism. When overeating and reduced physical activity result in obesity (right arrow), there is a reverse change in fasting insulin and leptin concentrations, tissues become resistant to both hormones as well as to S elicitation of metabolic EE. Due to insulin and leptin resistance, the ineffective compensatory increase in S activity to counteract further body fat, lean body mass, and bone accretion, mainly causes vasoconstriction and hypertension.