Anorexia nervosa (AN) is a debilitating, often lethal, restrictive-type eating disorder without an effective cure. The underlying neural basis of AN has remained elusive without an animal model that h Show more
Anorexia nervosa (AN) is a debilitating, often lethal, restrictive-type eating disorder without an effective cure. The underlying neural basis of AN has remained elusive without an animal model that has represented all typical AN symptoms. Here we show that aberrant activation of mediobasal hypothalamic (MBH) glutamatergic neurons led to lethal self-starvation, hyperactivity, anhedonia, social phobia, and increased anxiety, all of which represent typical symptoms of AN. These symptoms were selectively exhibited by targeted activation of MBH neurons expressing steroidogenic factor (SF1) and estrogen receptor alpha (ERa). Moreover, the elicited AN symptoms by activation of MBH glutamatergic or SF1/ERa neurons were rescued by removing release of glutamate or brain-derived neurotrophic factor (BDNF) from these neurons. Importantly, BDNF overexpression in SF1/ERa neurons promoted typical AN symptoms, which were suppressed by removing glutamate release. Thus, our findings identify aberrantly enhanced BDNF and consequent augmented glutamate release from SF1/ERa neurons as a neural basis underlying AN. Show less
The melanocortin pathway is well established to be critical for body-weight regulation in both rodents and humans. Despite extensive studies focusing on this pathway, the downstream brain sites that m Show more
The melanocortin pathway is well established to be critical for body-weight regulation in both rodents and humans. Despite extensive studies focusing on this pathway, the downstream brain sites that mediate its action are not clear. Here, we found that, among the known paraventricular hypothalamic (PVH) neuron groups, those expressing melanocortin receptors 4 (PVH Show less
The melanocortin action is well perceived for its ability to regulate body weight bidirectionally with its gain of function reducing body weight and loss of function promoting obesity. However, this n Show more
The melanocortin action is well perceived for its ability to regulate body weight bidirectionally with its gain of function reducing body weight and loss of function promoting obesity. However, this notion cannot explain the difficulty in identifying effective therapeutics toward treating general obesity via activation of the melanocortin action. Here, we provide evidence that altered melanocortin action is only able to cause one-directional obesity development. We demonstrate that chronic inhibition of arcuate neurons expressing proopiomelanocortin (POMC) or paraventricular hypothalamic neurons expressing melanocortin receptor 4 (MC4R) causes massive obesity. However, chronic activation of these neuronal populations failed to reduce body weight. Furthermore, gain of function of the melanocortin action through overexpression of MC4R, POMC or its derived peptides had little effect on obesity prevention or reversal. These results reveal a bias of the melanocortin action towards protection of weight loss and provide a neural basis behind the well-known, but mechanistically ill-defined, predisposition to obesity development. Show less