Suppression of food intake by Glp1r/Lepr-coexpressing neurons prevents obesity in mouse models.

The adipose-derived hormone leptin acts via its receptor (LepRb) in the brain to control energy balance. A potentially unidentified population of GABAergic hypothalamic LepRb neurons plays key roles in the restraint of food intake and body weight by leptin. To identify markers for candidate populations of LepRb neurons in an unbiased manner, we performed single-nucleus RNA-Seq of enriched mouse hypothalamic LepRb cells, identifying several previously unrecognized populations of hypothalamic LepRb neurons. Many of these populations displayed strong conservation across species, including GABAergic Glp1r-expressing LepRb (LepRbGlp1r) neurons, which expressed more Lepr than other LepRb cell populations. Ablating Lepr from LepRbGlp1r cells provoked hyperphagic obesity without impairing energy expenditure. Similarly, improvements in energy balance caused by Lepr reactivation in GABA neurons of otherwise Lepr-null mice required Lepr expression in GABAergic Glp1r-expressing neurons. Furthermore, restoration of Glp1r expression in LepRbGlp1r neurons in otherwise Glp1r-null mice enabled food intake suppression by the GLP1R agonist, liraglutide. Thus, the conserved GABAergic LepRbGlp1r neuron population plays crucial roles in the suppression of food intake by leptin and GLP1R agonists.

Maternal and postnatal high-fat diet consumption programs energy balance and hypothalamic melanocortin signaling in nonhuman primate offspring.

Maternal high-fat-diet (HFD) consumption during pregnancy decreased fetal body weight and impacted development of hypothalamic melanocortin neural circuitry in nonhuman primate offspring. We investigated whether these impairments during gestation persisted in juvenile offspring and examined the interaction between maternal and early postnatal HFD consumption. Adult dams consumed either a control diet (CTR; 15% calories from fat) or a high-saturated-fat diet (HFD; 37% calories from fat) during pregnancy. Offspring were weaned onto a CTR or HFD at ~8 mo of age. Offspring from HFD-fed dams displayed early catch-up growth and elevated body weight at 6 and 13 mo of age. Maternal and postnatal HFD exposure reduced the amount of agouti-related peptide fibers in the paraventricular nucleus of the hypothalamus. Postnatal HFD consumption also decreased the amount of agouti-related peptide fibers in the arcuate nucleus of the hypothalamus. Postnatal HFD was associated with decreased food intake and increased activity. These results support and extend our previous findings of maternal diet effects on fetal development and reveal, for the first time in a nonhuman primate model, that maternal HFD-induced disturbances in offspring body weight regulation extended past gestation into the juvenile period. Maternal HFD consumption increases the risk for offspring developing obesity, with the developmental timing of HFD exposure differentially impacting the melanocortin system and energy balance regulation. The present findings provide translational insight into human clinical populations, suggesting that profound health consequences may await individuals later in life following intrauterine and postnatal HFD exposure.

Leptin stimulates neuropeptide Y and cocaine amphetamine-regulated transcript coexpressing neuronal activity in the dorsomedial hypothalamus in diet-induced obese mice.

Neuropeptide Y (NPY) neurons in both the arcuate nucleus of the hypothalamus (ARH) and the dorsomedial hypothalamus (DMH) have been implicated in food intake and obesity. However, while ARH NPY is highly expressed in the lean animal, DMH NPY mRNA expression is observed only after diet-induced obesity (DIO). Furthermore, while ARH NPY neurons are inhibited by leptin, the effect of this adipokine on DMH NPY neurons is unknown. In this study we show that in contrast to the consistent expression in the ARH, DMH NPY mRNA expression was undetectable until after 10 weeks in mice fed a high-fat diet, and peaked at 20 weeks. Surprisingly, electrophysiological experiments demonstrated that leptin directly depolarized and increased the firing rate of DMH NPY neurons in DIO mice. To further differentiate the regulation of DMH and ARH NPY populations, fasting decreased expression of DMH NPY expression, while it increased ARH NPY expression. However, treatment with a leptin receptor antagonist failed to alter DMH NPY expression, indicating that leptin may not be the critical factor regulating mRNA expression. Importantly, we also demonstrated that DMH NPY neurons coexpress cocaine amphetamine-regulated transcript (CART); however, CART mRNA expression in the DMH peaked earlier in the progression of DIO. This study demonstrates novel and important findings. First, NPY and CART are coexpressed in the same neurons within the DMH, and second, leptin stimulates DMH NPY neurons. These studies suggest that during the progression of DIO, there is an unknown signal that drives the expression of the orexigenic NPY signal within the DMH, and that the chronic hyperleptinemia increases the activity of these NPY/CART neurons.