Reciprocally, maintenance of a group of obese rats on a laboratory chow diet for an extended period, during which the rats maintained obese body weights, does not restore leptin responsiveness, i.e., the group remains leptin resistant. This would suggest that obesity induces leptin resistance as a result of its effect on leptin levels. Results showed elevated levels of phosphorylated STAT-3 in the brains of HF rats, which could not be further stimulated when the rats were injected with leptin. Finally, the question of the availability of human data on the issue of leptin resistance was addressed. Impaired transport of leptin across the blood-brain barrier in obesity.
Obesity is associated with a decreased leptin transport across the blood-brain barrier in rats.
Two defects contribute to hypothalamic leptin resistance in mice with diet-induced obesity. Madiehe, AM, Schaffhauser, AO, Braymer, DH, Bray, GA and York. 589-593, May, 1996. Widdowson, PS, Upton, R, Buckingham, R, Arch, J and Williams, G. Inhibition of food response to intracerebroventricular injection of leptin is attenuated in rats with diet-induced obesity. In the case of leptin resistance, diet palatability can indirectly create a state of leptin resistance as a result of its effects on caloric intake and nutrient partitioning, if these effects result in obesity and elevated leptin levels.