Biology subjects

Norris, A. J.

Publications and source records attributed to Norris, A. J..

6 recordsLinked to original sources

bioRxiv2026

A Preoptic Neuronal Population Regulates Energy Expenditure and Balance

Maintaining energy balance requires coordination between food intake and energy expenditure, yet the neural pathways that regulate energy expenditure remain unclear. This study identifies kappa opioid receptor-expressing neurons in the preoptic area of the hypothalamus as a key regulator of whole-body metabolism. Using mouse models combined with fiber photometry, chemogenetic activation and inhibition, and chronic disruption of synaptic output, the results show that activity of these neurons follows daily pattern, are suppressed during feeding, and their inhibition acutely increases energy expenditure, body temperature, and activity levels. Long-term inhibition of this population produces sustained weight loss, selective reduction of white fat, preservation of lean mass and brown fat, and improved glucose tolerance even during high-fat feeding. These findings reveal a previously unrecognized circuit that links metabolic state with daily timing cues and suggest that targeting this neuronal population may offer new strategies for treating obesity and related metabolic disorders.

neuroscience↗

bioRxiv2025

Preoptic activation induces a torpor-like hypothermic and hypometabolic state that is cerebroprotective

Therapeutic hypothermia for stroke has been limited by shivering, increased metabolic demand, and poor patient tolerance. Engaging endogenous thermoregulatory circuits to lower body temperature may overcome these limitations and modulate metabolism, offering an integrated approach to cerebroprotection. Here, we show that chemogenetic activation of neurons in the preoptic area (POA) elicits a torpor-like state in mice, characterized by sustained hypothermia and hypometabolism. In an animal stroke model, this endogenous hypothermic state significantly reduced infarct volume and improved motor outcomes compared to controls, whereas maintaining normothermia attenuated these protective effects. To explore metabolic mechanisms contributing to this state, we performed untargeted metabolomic profiling 30 minutes after POA activation and identified coordinated shifts in nucleotide, phospholipid, and sphingolipid pathways. These rapid, temperature-dependent changes indicate a metabolically reprogrammed state that may enhance neuronal resilience during ischemic stress. Together, our findings suggest that POA-driven hypothermia confers cerebroprotection through specific metabolic adaptations with translational potential.

neuroscience↗

bioRxiv2022

Glutamatergic Supramammillary Nucleus Neurons Promote Active Coping to Stress

Threat-response neural circuits are conserved across species and play roles in normal behavior and psychiatric diseases. Maladaptive changes in these neural circuits contribute to stress, mood, and anxiety disorders. Active coping in response to stressors is a psychosocial factor associated with resilience against stress-induced mood and anxiety disorders. The neural circuitry underlying active coping is poorly understood, but the functioning of these circuits could be key for overcoming anxiety and related disorders. The supramammillary nucleus (SuM) has been suggested to be engaged by threat. SuM has many projections and contains a poorly understood diversity of populations. We identified a unique population of glutamatergic SuM neurons (SuMVGLUT2+::POA) based on projection to the preoptic area of the hypothalamus (POA) and found SuMVGLUT2+::POA neurons have extensive arborizations. SuMVGLUT2+::POA neurons project to brain areas that mediate various features of the stress and threat responses including the paraventricular nucleus thalamus (PVT), periaqueductal gray (PAG), and the habenula (Hb). Thus, SuMVGLUT2+::POA neurons are positioned as a hub, connecting to areas implicated in regulating stress responses. Here we report SuMVGLUT2+::POA neurons are recruited by diverse threatening stressors, and recruitment of SuMVGLUT2+::POA neurons correlated with active coping behaviors. We found that selective photoactivation of the SuMVGLUT2+::POA population drove aversion but not anxiety like behaviors. Activation of SuMVGLUT2+::POA neurons in the absence of acute stressors evoked active coping like behaviors and drove instrumental behavior (selective port activations) (Figure 6). Also, activation of SuMVGLUT2+::POA neurons was sufficient to convert passive coping strategies to active behaviors during acute stress. In contrast, we found activation of GABAergic (VGAT+) SuM neurons (SuMVGAT+) neurons did not alter drive aversion or active coping, but termination of photostimulation was followed by increased mobility in the forced swim test. These findings establish a new node in stress response circuitry that has projections to many brain areas, evokes flexible active coping behaviors, and offers new opportunities for furthering our neurobiological understanding of stress. O_FIG O_LINKSMALLFIG WIDTH=134 HEIGHT=200 SRC="FIGDIR/small/507167v4_fig6.gif" ALT="Figure 6"> View larger version (30K): org.highwire.dtl.DTLVardef@717f84org.highwire.dtl.DTLVardef@16ad323org.highwire.dtl.DTLVardef@4ba5b6org.highwire.dtl.DTLVardef@6c811e_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 6.C_FLOATNO SuMVGLUT2+::POA neurons can drive instrumental action-outcome operant behavior (A) Schematic of injection and implant in VGLUT2+ Cre mice and paradigm of testing in 10-minute trials with four days before a progressive ratio (PR) trial on day five. (B) Illustration of the testing paradigm and set up. 10 Hz photostimulation was applied during the trials. Activation of the active port triggered the house light and paused stimulation for 10 seconds. Also shown is the progressive ratio used with number of required port activations per reward on vertical axis and reward number on the horizontal. (C) Cre+ mice (n=11) activated the active port triggering significantly (****p<0.0001) more pauses in stimulation than Cre- mice (n=11) mice on all four days of testing. (D) Cre+ mice activated the port significantly (****p<0.0001, ***p<0.001) more than the Cre- mice on all four trials. (E) The time to first activation of the active port was significantly (*p=0.046) different during the first trial, and Cre+ mice activated the active port significantly (**p<0.01, **p<0.01, **p=0.034) faster on subsequent trials. (F) On the fifth day after four 10-minute trials, mice were tested for 30 minutes using a progressive ratio. Cre+ performed significantly (****p<0.001) more active port activations than Cre- mice and activated the inactive port significantly more (**p=0.001) times. Cre+ mice also triggered significantly (****p<0.001) more pauses in photostimulation than Cre- mice. (G) Individual data for a representative (n=7) cohort of Cre+ mice showing cumulative active port activations as a function of time during the progressive ratio test show on-going engagement of the active port throughout the 30-minute trial. (H) The cumulative pauses in photostimulation (rewards) earned as a function of time during the progressive ratio trial are shown for individual Cre+ mice. Mice earned between 7 and 11 pause rewards during the trial. All data plotted as means {+/-}SEM. C_FIG

neuroscience↗

bioRxiv2022

Enhanced food motivation in obese mice is controlled by D1R expressing spiny projection neurons in the nucleus accumbens.

Obesity is a chronic relapsing disorder that is caused by an excess of caloric intake relative to energy expenditure. In addition to homeostatic feeding mechanisms, there is growing recognition of the involvement of food reward and motivation in the development of obesity. However, it remains unclear how brain circuits that control food reward and motivation are altered in obese animals. Here, we tested the hypothesis that signaling through pro-motivational circuits in the core of the nucleus accumbens (NAc) is enhanced in the obese state, leading to invigoration of food seeking. Using a novel behavioral assay that quantifies physical work during food seeking, we confirmed that obese mice work harder than lean mice to obtain food, consistent with an increase in the relative reinforcing value of food in the obese state. To explain this behavioral finding, we recorded neural activity in the NAc core with both in vivo electrophysiology and cell-type specific calcium fiber photometry. Here we observed greater activation of D1-receptor expressing NAc spiny projection neurons (NAc D1SPNs) during food seeking in obese mice relative to lean mice. With ex vivo slice physiology we identified both pre- and post-synaptic mechanisms that contribute to this enhancement in NAc D1SPN activity in obese mice. Finally, blocking synaptic transmission from D1SPNs decreased physical work during food seeking and attenuated high-fat diet-induced weight gain. These experiments demonstrate that obesity is associated with a selective increase in the activity of D1SPNs during food seeking, which enhances the vigor of food seeking. This work also establishes the necessity of D1SPNs in the development of diet-induced obesity, establishing these neurons as a potential therapeutic target for preventing obesity.

neuroscience↗

bioRxiv2021

BCN057, a Modulator of GSK3b Induces KRAS G12D Mutant Pancreatic Cancer Cell Death

Effective treatment for Pancreatic Cancer remains a major challenge due to its resistance to radiation/chemotherapy and poor drug permeability. Moreover, treatment induced normal tissue toxicity, mainly to the duodenum and gastrointestinal epithelium, is common and is a dose limiting event, while toxicity to the pancreas is relatively rare1-3. Gastrointestinal toxicity, however, often results in interruption, reduction or premature withdrawal of anti-cancer therapy which is a very significant factor impacting the overall survival of patients being treated. Therefore, development of a therapeutic strategy to selectively sensitize tumor tissue without inducing normal tissue toxicity is important. In this manuscript, we show that the novel small molecule BCN057 can modulate chemo-sensitivity of oncogenic RAS pancreatic cancer cells while conversely protecting normal intestinal epithelium from off target toxicity. In particular, BCN 057 protects Lgr5 positive intestinal stem cells, thereby preserving barrier function. Further, it is demonstrated that BCN057 inhibits GSK3{beta} and thereby induces a pro-apoptotic phosphorylation pattern on c-Jun in KRAS G12D mutant pancreatic cancer cells (Panc-1) leading to the restoration of PTEN expression and consequent apoptosis. This appears to be a new mechanistic observation for the oncogenic RAS phenotype. Lastly, concurrent with its GSK3{beta} inhibition, BCN057 is a small molecule inhibitor of PD-1 expression on human T-lymphocytes co-cultured with human pancreatic cancer cells. In summary, BCN057 can promote synthetic lethality specifically to malignant cells and therefore should be considered to improve the therapeutic ratio in pancreatic and epithelial cancer treatment in conjunction with chemotherapy and radiation.

cancer biology↗

bioRxiv2020

Parabrachial Opioidergic Projections to Preoptic Hypothalamus Mediate Behavioral and Physiological Thermal Defenses

Maintaining stable body temperature through environmental thermal stressors requires detection of temperature changes, relay of information, and coordination of physiological and behavioral responses. Studies have implicated areas in the preoptic hypothalamic area (POA) and the parabrachial nucleus (PBN) as nodes in the thermosensory neural circuitry and indicate the opioid system within the POA is vital in regulating body temperate. In the present study we identify neurons projecting to the POA from PBN expressing the opioid peptides Dynorphin (Dyn) and Enkephalin (Enk). We determine that warm-activated PBN neuronal populations overlap with both Dyn and Enk expressing PBN populations. We demonstrate that Dyn and Enk expressing neurons are partially overlapping subsets of a glutamatergic population in the PBN. Using optogenetic approaches we selectively activate projections in the POA from PBN Dyn, Enk, and VGLUT2 expressing neurons. Our findings demonstrate that Dyn, Enk, and VGLUT2 expressing PBN neurons are critical for physiological and behavioral heat defense.

neuroscience↗