Mitochondrial stress-induced GFRAL signaling controls diurnal food intake and anxiety-like behavior

Growth differentiation factor 15 (GDF15) is a mitochondrial stress-induced cytokine that modulates energy balance in an endocrine manner. However, the importance of its brainstem-restricted receptor GDNF family receptor alpha-like (GFRAL) to mediate endocrine GDF15 signaling to the brain upon mitochondrial dysfunction is still unknown. Using a mouse model with muscle-specific mitochondrial dysfunction, we here show that GFRAL is required for activation of systemic energy metabolism via daytime-restricted anorexia but not responsible for muscle wasting. We further find that muscle mitochondrial stress response involves a GFRAL-dependent induction of hypothalamic corticotropin-releasing hormone, without elevated corticosterone levels. Finally, we identify that GFRAL signaling governs an anxiety-like behavior in male mice with muscle mitochondrial dysfunction, with females showing a less robust GFRAL-dependent anxiety-like phenotype. Together, we here provide novel evidence of a mitochondrial stress-induced muscle–brain crosstalk via the GDF15-GFRAL axis to modulate food intake and anxiogenic behavior

Organization of neural systems expressing melanocortin-3 receptors in the mouse brain: Evidence for sexual dimorphism

The central melanocortin system is fundamentally important for controlling food intake and energy homeostasis. Melanocortin-3 receptor (MC3R) is one of two major receptors of the melanocortin system found in the brain. In contrast to the well-characterized melanocortin-4 receptor (MC4R), little is known regarding the organization of MC3R-expressing neural circuits. To increase our understanding of the intrinsic organization of MC3R neural circuits, identify specific differences between males and females, and gain a neural systems level perspective of this circuitry, we conducted a brain-wide mapping of neurons labeled for MC3R and characterized the distribution of their projections. Analysis revealed MC3R neuronal and terminal labeling in multiple brain regions that control a diverse range of physiological functions and behavioral processes. Notably, dense labeling was observed in the hypothalamus, as well as areas that share considerable connections with the hypothalamus, including the cortex, amygdala, thalamus, and brainstem. Additionally, MC3R neuronal labeling was sexually dimorphic in several areas, including the anteroventral periventricular area, arcuate nucleus, principal nucleus of the bed nucleus of the stria terminalis, and ventral premammillary region. Altogether, anatomical evidence reported here suggests that MC3R has the potential to influence several different classes of motivated behavior that are essential for survival, including ingestive, reproductive, defensive, and arousal behaviors, and is likely to modulate these behaviors differently in males and females.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/174918/1/cne25379.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/174918/2/cne25379_am.pd

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ObjectiveIn adult organisms, a number of receptors have been identified which modulate metabolic processes related to peptides derived from the intestinal tract. These receptors play significant roles in glucose homeostasis, food intake and energy balance. Here we assess these classical metabolic receptors and their expression as well as their potential role in early development of hypothalamic neuronal circuits.MethodsChow-fed C57BL6/N female mice were mated and hypothalamic tissue was collected from offspring across postnatal development (postnatal day 7–21). Subsequent qPCR and Western Blot analyses were used to determine mRNA and protein changes in gut-derived peptide hormone receptors. Correlations to body weight, blood glucose and circulating leptin levels were analyzed.ResultsWe describe the gene expression and dynamic protein regulation of key gut-derived peptide hormone receptors in the early postnatal period of the mouse brain. Specifically, we show changes to Gastric inhibitory polypeptide receptor (GIPR), glucagon-like peptide 1 receptor (GLP1R), and cholecystokinin receptor 2 (CCK2R) in the developing hypothalamus. The changes to GIPR and InsR seem to be strongly negatively correlated with body weight.ConclusionsThis comprehensive analysis underscores the need to understand the roles of maternal-derived circulating gut hormones and their direct effect on offspring brain development.</div

Physiological characteristics across development and insulin receptor expression postnatally.

A) Hypothalamic samples were collected at timepoints across development for analysis. B) Body weight and C) blood glucose levels of male and female offspring were analyzed. InsR protein expression in D) males and E) females across early postnatal development. Open circles (males) or squares (females) represent individual data points. Data is plotted as Mean ± SEM * = p<0.05, ** = p<0.01.</p

Trizol composition.

ObjectiveIn adult organisms, a number of receptors have been identified which modulate metabolic processes related to peptides derived from the intestinal tract. These receptors play significant roles in glucose homeostasis, food intake and energy balance. Here we assess these classical metabolic receptors and their expression as well as their potential role in early development of hypothalamic neuronal circuits.MethodsChow-fed C57BL6/N female mice were mated and hypothalamic tissue was collected from offspring across postnatal development (postnatal day 7–21). Subsequent qPCR and Western Blot analyses were used to determine mRNA and protein changes in gut-derived peptide hormone receptors. Correlations to body weight, blood glucose and circulating leptin levels were analyzed.ResultsWe describe the gene expression and dynamic protein regulation of key gut-derived peptide hormone receptors in the early postnatal period of the mouse brain. Specifically, we show changes to Gastric inhibitory polypeptide receptor (GIPR), glucagon-like peptide 1 receptor (GLP1R), and cholecystokinin receptor 2 (CCK2R) in the developing hypothalamus. The changes to GIPR and InsR seem to be strongly negatively correlated with body weight.ConclusionsThis comprehensive analysis underscores the need to understand the roles of maternal-derived circulating gut hormones and their direct effect on offspring brain development.</div

Protein expression correlations with glucose levels and body weight.

INSR (A), CCK2R (B), GLP1R (C) and GIPR (D) protein expression across development in both sexes correlated with glucose (mg/dL) levels. INSR (E), CCK2R (F), GLP1R (G) and GIPR (H) protein expression across development in both sexes correlated with body weight. Circles (males) or squares (females) represent individual data points, color-coded by age.</p

qPCR data.

Raw qPCR data of Glp1r, Gipr, Cckbr and Gapdh across the 4 postnatal time-points in both males and females are shown, together with the analysis of their expression using the 2(-ΔΔCT) method. (XLSX)</p

Primary antibodies used for Western blot.

ObjectiveIn adult organisms, a number of receptors have been identified which modulate metabolic processes related to peptides derived from the intestinal tract. These receptors play significant roles in glucose homeostasis, food intake and energy balance. Here we assess these classical metabolic receptors and their expression as well as their potential role in early development of hypothalamic neuronal circuits.MethodsChow-fed C57BL6/N female mice were mated and hypothalamic tissue was collected from offspring across postnatal development (postnatal day 7–21). Subsequent qPCR and Western Blot analyses were used to determine mRNA and protein changes in gut-derived peptide hormone receptors. Correlations to body weight, blood glucose and circulating leptin levels were analyzed.ResultsWe describe the gene expression and dynamic protein regulation of key gut-derived peptide hormone receptors in the early postnatal period of the mouse brain. Specifically, we show changes to Gastric inhibitory polypeptide receptor (GIPR), glucagon-like peptide 1 receptor (GLP1R), and cholecystokinin receptor 2 (CCK2R) in the developing hypothalamus. The changes to GIPR and InsR seem to be strongly negatively correlated with body weight.ConclusionsThis comprehensive analysis underscores the need to understand the roles of maternal-derived circulating gut hormones and their direct effect on offspring brain development.</div

Cholecystokinin 2 receptor, glucagon-like peptide receptor and Gastric inhibitory polypeptide receptor expression in postnatal development.

Cckbr mRNA expression across postnatal days in A) males and D) female animals. CCK2R protein expression in G) males and J) females across early postnatal development. Glp1r mRNA expression across postnatal days in B) males and E) female animals. GLP1R protein expression in H) males and K) females across early postnatal development. Gipr mRNA expression across postnatal days in C) males and F) female animals. GIPR protein expression in I) males and L) females across early postnatal development. Open circles (males) or squares (females) represent individual data points. Representative blots are shown for each protein assessed. Data is plotted as Mean ± SEM * = p<0.05, ** = p<0.01, *** = p<0.001, **** = p<0.0001.</p