Animals must respond to various threats to survive. Neurons that express calcitonin gene-related peptide (CGRP) in the parabrachial nucleus (PBN) relay sensory signals that contribute to satiation and pain-induced fear behavior, but it is unknown how they encode these distinct processes. By recording calcium transients in vivo from individual CGRPPBN neurons, we reveal that most neurons are activated by noxious cutaneous (shock, heat, itch) and visceral stimuli (lipopolysaccharide). These same neurons are inhibited during feeding, but become activated during satiation, consistent with evidence that CGRPPBN neurons prevent overeating. CGRPPBN neurons are also activated during consumption of novel food or by an auditory cue that was previously paired with electrical foot shocks. Correspondingly, silencing CGRPPBN neurons attenuates expression of food neophobia and conditioned fear responses. Therefore, in addition to transducing primary sensory danger signals, CGRPPBN neurons promote affective-behavioral states that limit harm in response to potential threats.

SUMMARY The lateral parabrachial nucleus is a conduit for visceral signals that cause anorexia. We previously identified a subset of neurons located in the external lateral parabrachial nucleus (PBel) that express calcitonin gene-related peptide (CGRP) and inhibit feeding when activated by illness mimetics. We report here that in otherwise normal mice, functional inactivation of CGRP neurons markedly increases meal size, with meal frequency being reduced in a compensatory manner, and renders mice insensitive to the anorexic effects of meal-related satiety peptides. Furthermore, CGRP neurons are directly innervated by orexigenic hypothalamic AgRP neurons, and photostimulation of AgRP fibers supplying the PBel delays satiation by inhibiting CGRP neurons, thereby contributing to AgRP-driven hyperphagia. By establishing a role for CGRP neurons in the control of meal termination and as a downstream mediator of feeding elicited by AgRP neurons, these findings identify a node in which hunger and satiety circuits interact to control feeding behavior.

Brain regions that regulate fluid satiation are not well characterized, yet are essential for understanding fluid homeostasis. We found that oxytocin-receptor-expressing neurons in the parabrachial nucleus of mice (OxtrPBN neurons) are key regulators of fluid satiation. Chemogenetic activation of OxtrPBN neurons robustly suppressed noncaloric fluid intake, but did not decrease food intake after fasting or salt intake following salt depletion; inactivation increased saline intake after dehydration and hypertonic saline injection. Under physiological conditions, OxtrPBN neurons were activated by fluid satiation and hypertonic saline injection. OxtrPBN neurons were directly innervated by oxytocin neurons in the paraventricular hypothalamus (OxtPVH neurons), which mildly attenuated fluid intake. Activation of neurons in the nucleus of the solitary tract substantially suppressed fluid intake and activated OxtrPBN neurons. Our results suggest that OxtrPBN neurons act as a key node in the fluid satiation neurocircuitry, which acts to decrease water and/or saline intake to prevent or attenuate hypervolemia and hypernatremia.

SUMMARY Food aversions develop when the taste of a novel food is associated with sickness, which often occurs after food poisoning or chemotherapy treatment. We identified calcitonin gene-related peptide (CGRP) neurons in the parabrachial nucleus (PBN) as sufficient and necessary for establishing a conditioned taste aversion (CTA). Photoactivating projections from CGRPPBN neurons in either the central nucleus of the amygdala or the bed nucleus of the stria terminalis can also induce robust CTA. CGRPPBN neurons undergo plasticity following CTA and inactivation of either Arc or Grin1 (genes involved in memory consolidation), prevents establishment of a strong CTA. Calcium imaging reveals that the food reactivates CGRPPBN neurons after conditioning. Inhibition of these neurons or inactivation of the Gril1 gene after conditioning attenuates CTA expression. Our results indicate that CGRPPBN neurons not only play a key role for learning food aversions, but also contribute to the maintenance and expression of those memories.

Type 2 diabetes mellitus (DM) is a progressive disease characterized by elevated plasma glucose levels. Type 2 DM results from a combination of factors affecting both peripheral tissue insulin sensitivity and β-cell function. A survey of the scientific literature on DM, glucose toxicity, hyperglycemia, nephropathy, neuropathy, reactive oxygen species, and retinopathy cited on PubMed/Medline from January 1975 to May 2011 was conducted. The relevant publications, chosen at the author's discretion, were used to synthesize this narrative review article. Chronic hyperglycemia imposes damage (glucose toxicity) on a number of cell types and is strongly correlated with the myriad of DM-related complications. Tissues most vulnerable to the effects of prolonged elevated plasma glucose levels include pancreatic β cells and vascular endothelial cells. The ensuing β-cell dysfunction promotes decreased insulin synthesis and secretion, further perpetuating the associated hyperglycemia. As for the vascular endothelium, chronic hyperglycemia is strongly correlated with many DM-related microvascular complications, including retinopathy, nephropathy, and neuropathy. The role of hyperglycemia in macrovascular complications is not well defined. Pathophysiologic modifications that arise in response to chronic hyperglycemia persist and may promote DM-related complications that manifest years later, even if plasma glucose levels have been brought under control. Increasing awareness of the mechanisms by which even modest hyperglycemia promotes long-lasting tissue damage highlights the need to achieve early tight glycemic control in patients with DM before substantial disease progression.

Anorexia is a common manifestation of chronic diseases, including cancer. Here we investigate the contribution to cancer anorexia made by calcitonin gene-related peptide (CGRP) neurons in the parabrachial nucleus (PBN) that transmit anorexic signals. We show that CGRPPBN neurons are activated in mice implanted with Lewis lung carcinoma (LLC) cells. Inactivation of CGRPPBN neurons before tumor implantation prevents anorexia and loss of lean mass, and their inhibition after symptom onset reverses anorexia. CGRPPBN neurons are also activated in Apcmin/+ mice that develop intestinal cancer and lose weight despite the absence of reduced food intake. Inactivation of CGRPPBN neurons in Apcmin/+ mice permits hyperphagia that counteracts weight loss, revealing a role for these neurons in a “non-anorexic” cancer model. We also demonstrate that inactivation of CGRPPBN neurons prevents lethargy, anxiety and malaise associated with cancer. These findings establish CGRPPBN neurons as key mediators of cancer-induced appetite suppression and associated behavioral changes.

Objective: To assess differences in psychological outcomes as well as risk and protective factors for these outcomes among several USA ethnic groups and identify correlates of these psychological outcomes among adults with diabetes in the second Diabetes Attitudes, Wishes and Needs (DAWN2*) study.

Hispanics experience a higher rate of diabetes than non-Hispanic whites and tend to have worse glycemic control and a greater risk of diabetes-related complications. Once oral antidiabetic agents become insufficient, insulin plays an important role in achieving glycemic goals. However, many Hispanic patients are resistant to initiating insulin therapy or hesitant to increase doses, as necessary, to control their glucose levels. Barriers to insulin therapy include socioeconomic issues (eg, cost, insurance status), language difficulties, poor health literacy, and cultural beliefs that impact the patient-provider relationship and negatively affect patients' perceptions of diabetes and insulin. Healthcare providers can help overcome these issues and improve patient-provider communication by practicing culturally competent care. Implementation of a simple titration regimen using once-daily basal insulin may enable Hispanic patients to maintain glycemic control and improve outcomes.