A Hypothalamic Circuit that Modulates Feeding and Parenting Behaviors.

Across mammalian species, new mothers undergo considerable behavioral changes to nurture their offspring and meet the caloric demands of milk production. While many neural circuits underlying feeding and parenting behaviors are well characterized, it is unclear how these different circuits interact and adapt during lactation. Here, we characterized the transcriptomic changes in the arcuate nucleus (ARC) and the medial preoptic area (MPOA) of the mouse hypothalamus in response to lactation and hunger.

Housing mice near vs. below thermoneutrality affects drug-induced weight loss but does not improve prediction of efficacy in humans.

Evaluation of weight loss drugs is usually performed in diet-induced obese mice housed at ∼22°C. This is a cold stress that increases energy expenditure by ∼35% compared to thermoneutrality (∼30°C), which may overestimate drug-induced weight loss. We investigated five anti-obesity mechanisms that have been in clinical development, comparing weight loss in mice housed at 22°C vs.

Network-level encoding of local neurotransmitters in cortical astrocytes.

Astrocytes, the most abundant non-neuronal cell type in the mammalian brain, are crucial circuit components that respond to and modulate neuronal activity through calcium (Ca) signalling. Astrocyte Ca activity is highly heterogeneous and occurs across multiple spatiotemporal scales-from fast, subcellular activity to slow, synchronized activity across connected astrocyte networks-to influence many processes. However, the inputs that drive astrocyte network dynamics remain unclear.

Network-level encoding of local neurotransmitters in cortical astrocytes.

Astrocytes-the most abundant non-neuronal cell type in the mammalian brain-are crucial circuit components that respond to and modulate neuronal activity via calcium (Ca ) signaling . Astrocyte Ca activity is highly heterogeneous and occurs across multiple spatiotemporal scales: from fast, subcellular activity to slow, synchronized activity that travels across connected astrocyte networks . Furthermore, astrocyte network activity has been shown to influence a wide range of processes .

Loss of Otopetrin 1 affects thermoregulation during fasting in mice.

Objective: Otopetrin 1 (OTOP1) is a proton channel that is highly expressed in brown adipose tissue. We examined the physiology of Otop1-/- mice, which lack functional OTOP1.

Methods: Mice were studied by indirect calorimetry and telemetric ambulatory body temperature monitoring.

Norepinephrine links astrocytic activity to regulation of cortical state.

Cortical state, defined by population-level neuronal activity patterns, determines sensory perception. While arousal-associated neuromodulators-including norepinephrine (NE)-reduce cortical synchrony, how the cortex resynchronizes remains unknown. Furthermore, general mechanisms regulating cortical synchrony in the wake state are poorly understood.

The metabolic cost of physical activity in mice using a physiology-based model of energy expenditure.

Objective: Physical activity is a major component of total energy expenditure (TEE) that exhibits extreme variability in mice. Our objective was to construct a general, physiology-based model of TEE to accurately quantify the energy cost of physical activity.

Methods: Spontaneous home cage physical activity, body temperature, TEE, and energy intake were measured with frequent sampling.

In vivo phenotypic validation of adenosine receptor-dependent activity of non-adenosine drugs.

Some non-adenosinergic drugs are reported to also act through adenosine receptors (ARs). We used mouse hypothermia, which can be induced by agonism at any of the four ARs, as an in vivo screen for adenosinergic effects. An AR contribution was identified when a drug caused hypothermia in wild type mice that was diminished in mice lacking all four ARs (quadruple knockout, QKO).

Dopamine activates astrocytes in prefrontal cortex via α1-adrenergic receptors.

The prefrontal cortex (PFC) is a hub for cognitive control, and dopamine profoundly influences its functions. In other brain regions, astrocytes sense diverse neurotransmitters and neuromodulators and, in turn, orchestrate regulation of neuroactive substances. However, basic physiology of PFC astrocytes, including which neuromodulatory signals they respond to and how they contribute to PFC function, is unclear.

Finding a sweet spot for leptin.

Non-alcoholic fatty liver disease (NAFLD) is a growing public health problem that progresses to serious liver disease in some patients and for which there are no FDA-approved therapies. In this issue of Med, Akinci et al. present encouraging preliminary data showing that treatment with recombinant leptin has beneficial effects on NAFLD.

Engineering living and regenerative fungal-bacterial biocomposite structures.

Engineered living materials could have the capacity to self-repair and self-replicate, sense local and distant disturbances in their environment, and respond with functionalities for reporting, actuation or remediation. However, few engineered living materials are capable of both responsivity and use in macroscopic structures. Here we describe the development, characterization and engineering of a fungal-bacterial biocomposite grown on lignocellulosic feedstocks that can form mouldable, foldable and regenerative living structures.

The effects of housing density on mouse thermal physiology depend on sex and ambient temperature.

Objective: To improve understanding of mouse energy homeostasis and its applicability to humans, we quantitated the effects of housing density on mouse thermal physiology in both sexes.

Methods: Littermate wild type and Brs3-null mice were single- or group- (three per cage) housed and studied by indirect calorimetry with continuous measurement of core body temperature, energy expenditure, physical activity, and food intake.

Results: At 23 °C, below thermoneutrality, single-housed males had a lower body temperature and unchanged metabolic rate compared to group-housed controls.

Adenosine A receptor is dispensable for hepatocyte glucose metabolism and insulin sensitivity.

Hepatic insulin resistance (IR) and enhanced hepatic glucose production (HGP) are key features of type 2 diabetes (T2D), contributing to fasting hyperglycemia. Adenosine receptors (ARs) are G protein-coupled and expressed in hepatocytes. Here, we explored the role of hepatic G-coupled AAR on insulin resistance and glucose fluxes associated with obesity.

Cre Recombinase Driver Mice Reveal Lineage-Dependent and -Independent Expression of Brs3 in the Mouse Brain.

Bombesin receptor subtype-3 (BRS3) is an orphan receptor that regulates energy homeostasis. We compared driver mice with constitutive or inducible Cre recombinase activity. The constitutive BRS3-Cre mice show a reporter signal (Cre-dependent tdTomato) in the adult brain because of lineage tracing in the dentate gyrus, striatal patches, and indusium griseum, in addition to sites previously identified in the inducible BRS3-Cre mice (including hypothalamic and amygdala subregions, and parabrachial nucleus).

Preoptic BRS3 neurons increase body temperature and heart rate via multiple pathways.

The preoptic area (POA) is a key brain region for regulation of body temperature (Tb), dictating thermogenic, cardiovascular, and behavioral responses that control Tb. Previously characterized POA neuronal populations all reduced Tb when activated. Using mice, we now identify POA neurons expressing bombesin-like receptor 3 (POA) as a population whose activation increased Tb; inversely, acute inhibition of these neurons reduced Tb.

Cortical astrocytes independently regulate sleep depth and duration via separate GPCR pathways.

Non-rapid eye movement (NREM) sleep, characterized by slow-wave electrophysiological activity, underlies several critical functions, including learning and memory. However, NREM sleep is heterogeneous, varying in duration, depth, and spatially across the cortex. While these NREM sleep features are thought to be largely independently regulated, there is also evidence that they are mechanistically coupled.

How does obesity promote breast cancer tumor growth?

Obesity is a risk factor for many cancers. Maguire et al. (2021) found increased creatine synthesis by the adipocytes adjacent to breast cancers in obese mice.

Adenosine A3 agonists reverse neuropathic pain via T cell-mediated production of IL-10.

The A3 adenosine receptor (A3AR) has emerged as a therapeutic target with A3AR agonists to tackle the global challenge of neuropathic pain, and investigation into its mode of action is essential for ongoing clinical development. Immune cell A3ARs, and their activation during pathology, modulate cytokine release. Thus, the use of immune cells as a cellular substrate for the pharmacological action of A3AR agonists is enticing, but unknown.

Activation of neuronal adenosine A1 receptors causes hypothermia through central and peripheral mechanisms.

Extracellular adenosine, a danger signal, can cause hypothermia. We generated mice lacking neuronal adenosine A1 receptors (A1AR, encoded by the Adora1 gene) to examine the contribution of these receptors to hypothermia. Intracerebroventricular injection of the selective A1AR agonist (Cl-ENBA, 5'-chloro-5'-deoxy-N6-endo-norbornyladenosine) produced hypothermia, which was reduced in mice with deletion of A1AR in neurons.