Future avenues in Drosophila mushroom body research.

How does the brain translate sensory information into complex behaviors? With relatively small neuronal numbers, readable behavioral outputs, and an unparalleled genetic toolkit, the Drosophila mushroom body (MB) offers an excellent model to address this question in the context of associative learning and memory. Recent technological breakthroughs, such as the freshly completed full-brain connectome, multiomics approaches, CRISPR-mediated gene editing, and machine learning techniques, led to major advancements in our understanding of the MB circuit at the molecular, structural, physiological, and functional levels. Despite significant progress in individual MB areas, the field still faces the fundamental challenge of resolving how these different levels combine and interact to ultimately control the behavior of an individual fly. In this review, we discuss various aspects of MB research, with a focus on the current knowledge gaps, and an outlook on the future methodological developments required to reach an overall view of the neurobiological basis of learning and memory.

Extended Rotational Coherence of Polar Molecules in an Elliptically Polarized Trap.

We demonstrate long rotational coherence of individual polar molecules in the motional ground state of an optical trap. In the present, previously unexplored regime, the rotational eigenstates of molecules are dominantly quantized by trapping light rather than static fields, and the main source of decoherence is differential light shift. In an optical tweezer array of NaCs molecules, we achieve a three-orders-of-magnitude reduction in differential light shift by changing the trap's polarization from linear to a specific "magic" ellipticity. With spin-echo pulses, we measure a rotational coherence time of 62(3) ms (one pulse) and 250(40) ms (up to 72 pulses), surpassing the projected duration of resonant dipole-dipole entangling gates by orders of magnitude.

Crossed optical cavities with large mode diameters.

We report on a compact, ultrahigh-vacuum compatible optical assembly to create large-scale, two-dimensional optical lattices for use in experiments with ultracold atoms. The assembly consists of an octagon-shaped spacer made from ultra-low-expansion glass, to which we optically contact four fused silica cavity mirrors, making it highly mechanically and thermally stable. The mirror surfaces are nearly plane-parallel, which allows us to create two perpendicular cavity modes with diameters ∼1m m. Such large mode diameters are desirable to increase the optical lattice homogeneity, but lead to strong angular sensitivities of the coplanarity between the two cavity modes. We demonstrate a procedure to precisely position each mirror substrate that achieves a deviation from coplanarity of d=1(5)µm. Creating large optical lattices at arbitrary visible and near-infrared wavelengths requires significant power enhancements to overcome limitations in the available laser power. The cavity mirrors have a customized low-loss mirror coating that enhances the power at a set of relevant visible and near-infrared wavelengths by up to 3 orders of magnitude..

Alcohol-induced aggression in Drosophila.

Alcohol-induced aggression is a destructive and widespread phenomenon associated with violence and sexual assault. However, little is understood concerning its mechanistic origin. We have developed a Drosophila melanogaster model to genetically dissect and understand the phenomenon of sexually dimorphic alcohol-induced aggression. Males with blood alcohol levels of 0.04-mg/ml BAC were less aggressive than alcohol-naive males, but when the BAC had dropped to ~0.015 mg/ml, the alcohol-treated males showed an increase in aggression toward other males. This aggression-promoting treatment is referred to as the post-ethanol aggression (PEA) treatment. Females do not show increased aggression after the same treatment. PEA-treated males also spend less time courting and attempt to copulate earlier than alcohol-naive flies. PEA treatment induces expression of the FruM transcription factor (encoded by a male-specific transcript from the fruitless gene), whereas sedating doses of alcohol reduce FruM expression and reduce male aggression. Transgenic suppression of FruM induction also prevents alcohol-induced aggression. In male flies, alcohol-induced aggression is dependent on the male isoform of the fruitless transcription factor (FruM). Low-dose alcohol induces FruM expression and promotes aggression, whereas higher doses of alcohol suppress FruM and suppress aggression.

Monitoring food preference in Drosophila by oligonucleotide tagging.

Drosophila melanogaster is a powerful model organism for dissecting the neurogenetic basis of appetitive and aversive behaviors. However, some methods used to assay food preference require or cause starvation. This can be problematic for fly ethanol research because it can be difficult to dissociate caloric preference for ethanol from pharmacological preference for the drug. We designed BARCODE, a starvation-independent assay that uses trace levels of oligonucleotide tags to differentially mark food types. In BARCODE, flies feed ad libitum, and relative food preference is monitored by qPCR of the oligonucleotides. Persistence of the ingested oligomers within the fly records the feeding history of the fly over several days. Using BARCODE, we identified a sexually dimorphic preference for ethanol. Females are attracted to ethanol-laden foods, whereas males avoid consuming it. Furthermore, genetically feminizing male mushroom body lobes induces preference for ethanol. In addition, we demonstrate that BARCODE can be used for multiplex diet measurements when animals are presented with more than two food choices.

Undertreatment of women with locoregionally advanced head and neck cancer.

BACKGROUND: It is difficult to predict whether a patient with head and neck cancer (HNC) is more likely to die of the cancer or another comorbidity. Competing event models can help to identify individual patients or groups of patients who may be undertreated or overtreated in clinical practice. METHODS: Patients with HNC (n = 884), aged 18 to 85 years and diagnosed from 2000 to 2015 with stage II to IVB disease according to the seventh edition of the American Joint Committee on Cancer system, were identified. With a generalized competing event (GCE) model that controlled for age, sex, tumor site, surgical treatment, and Charlson Comorbidity Index (CCI), the association between these factors and the relative hazard for cancer mortality was determined. Logistic regression models were used to estimate the odds of receiving platinum-based chemoradiotherapy or a less intensive therapy, with adjustments made for age, sex, tumor site, CCI, stage, smoking, and alcohol abuse history. RESULTS: Compared with men, women had an increased relative hazard ratio for death from HNC versus other causes, which was reported as an adjusted ω+ ratio comparing women with men (ω+ ratio, 1.95; 95% CI, 1.09-3.49), even though they were less likely to receive intensive chemoradiotherapy than men (adjusted odds ratio, 0.69; 95% CI, 0.48-0.99). CONCLUSIONS: These findings indicate that women in this cohort may be undertreated in clinical practice and potentially miss the opportunity for their HNC to be aggressively treated. This study supports the use of GCE models to identify patients who are potentially undertreated and may also help to guide future research in health disparities.

Development of high throughput screening methods for inhibitors of ClpC1P1P2 from Mycobacteria tuberculosis.

Tuberculosis affects about 100 million people worldwide and causes nearly 2 million deaths annually. It has been estimated that one third of all humans is infected with latent Mycobacterium tuberculosis (Mtb). Moreover, Mtb has become increasingly resistant to available antibiotics. Consequently, it is important to identify and characterize new therapeutic targets in Mtb and to synthesize selective inhibitors. ClpP1, ClpP2 and their associated regulatory ATPases, ClpX and ClpC1 are required for the growth of Mtb and for its virulence during murine infection and are highly attractive drug targets, especially since they are not present in the cytosol of mammalian cells, and they differ markedly from the mitochondrial ClpP complex. The importance of these proteins in Mtb is emphasized by the existence of several natural antibiotics targeting this system. In order to find new inhibitors of ClpC1P1P2 system, we developed an assay based on the ATP-dependent degradation of a fluorescent protein substrate. The hits obtained were further characterized with a set of secondary assays to identify precise targets within a complex. A large library of compounds was screened and led to the identification of a ClpC1 ATPase inhibitor demonstrating that this approach can be used in future searches for anti-TB agents.

F654A and K558Q Mutations in NMDA Receptor 1 Affect Ethanol-Induced Behaviors in Drosophila.

BACKGROUND: N-methyl-D-aspartate (NMDA) receptors regulate synaptic plasticity and modulate a wide variety of behaviors. Mammalian NMDA receptors are inhibited by ethanol (EtOH) even at low concentrations. In mice, the F639A mutation in transmembrane domain (TMD) 3 of the NR1 subunit reduces EtOH sensitivity of the receptor and, in some paradigms, reduces behavioral EtOH sensitivity and increases EtOH consumption. We tested the fly equivalent of the F639A and K544Q mutations for effects on EtOH sensitivity. Drosophila shows a high degree of behavioral and mechanistic conservation in its responses to EtOH. METHODS: Homologous recombination and CRISPR/Cas9 genome editing were used to generate amino acid changes in the Drosophila NMDAR1 gene, yielding F654A and K558Q alleles. Animals were tested for the degree of EtOH sensitivity, the ability to acquire tolerance to EtOH, EtOH drinking preference, circadian rhythmicity, learning, and locomotor defects. RESULTS: We observed that mutating the NMDAR1 channel also reduces EtOH sensitivity in adult flies. However, in flies, it was the K558Q mutation (orthologous to K544Q in mice) that reduces EtOH sensitivity in a recovery-from-sedation assay. The effects of the F654A mutation (orthologous to F639A in mice) were substantially different in flies than in mammals. In flies, F654A mutation produces phenotypes opposite those in mammals. In flies, the mutant allele is homozygous viable, does not seem to affect health, and increases EtOH sensitivity. Both mutations increased feeding but did not alter the animal's preference for 5% EtOH food. F654A depressed circadian rhythmicity and the capacity of males to court, but it did not depress the capacity for associative learning. K554Q, on the other hand, has little effect on circadian rhythmicity, only slightly suppresses male courtship, and is a strong learning mutant. CONCLUSIONS: Mutations in TMD 3 and in the extracellular-vestibule calcium-binding site of the NR1 NMDA subunit affect EtOH sensitivity in Drosophila.

The Role of Intercalated Cell Nedd4-2 in BP Regulation, Ion Transport, and Transporter Expression.

BackgroundNedd4-2 is an E3 ubiquitin-protein ligase that associates with transport proteins, causing their ubiquitylation, and then internalization and degradation. Previous research has suggested a correlation between Nedd4-2 and BP. In this study, we explored the effect of intercalated cell (IC) Nedd4-2 gene ablation on IC transporter abundance and function and on BP.Methods We generated IC Nedd4-2 knockout mice using Cre-lox technology and produced global pendrin/Nedd4-2 null mice by breeding global Nedd4-2 null (Nedd4-2-/- ) mice with global pendrin null (Slc26a4-/- ) mice. Mice ate a diet with 1%-4% NaCl; BP was measured by tail cuff and radiotelemetry. We measured transepithelial transport of Cl- and total CO2 and transepithelial voltage in cortical collecting ducts perfused in vitro Transporter abundance was detected with immunoblots, immunohistochemistry, and immunogold cytochemistry.Results IC Nedd4-2 gene ablation markedly increased electroneutral Cl-/HCO3- exchange in the cortical collecting duct, although benzamil-, thiazide-, and bafilomycin-sensitive ion flux changed very little. IC Nedd4-2 gene ablation did not increase the abundance of type B IC transporters, such as AE4 (Slc4a9), H+-ATPase, barttin, or the Na+-dependent Cl-/HCO3- exchanger (Slc4a8). However, IC Nedd4-2 gene ablation increased CIC-5 total protein abundance, apical plasma membrane pendrin abundance, and the ratio of pendrin expression on the apical membrane to the cytoplasm. IC Nedd4-2 gene ablation increased BP by approximately 10 mm Hg. Moreover, pendrin gene ablation eliminated the increase in BP observed in global Nedd4-2 knockout mice.Conclusions IC Nedd4-2 regulates Cl-/HCO3- exchange in ICs., Nedd4-2 gene ablation increases BP in part through its action in these cells.

Advance Directive Utilization Is Associated with Less Aggressive End-of-Life Care in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation.

Allogeneic hematopoietic cell transplantation (HCT) is associated with significant morbidity and mortality, making advance care planning (ACP) and management especially important in this patient population. A paucity of data exists on the utilization of ACP among allogeneic HCT recipients and the relationship between ACP and intensity of healthcare utilization in these patients. We performed a retrospective review of patients receiving allogeneic HCT at our institution from 2008 to 2015 who had subsequently died after HCT. Documentation and timing of advance directive (AD) completion were abstracted from the electronic medical record. Outcomes of interest included use of intensive care unit (ICU) level of care at any time point after HCT, within 30 days of death, and within 14 days of death; use of mechanical ventilation at any time after HCT; and location of death. Univariate logistic regression was performed to explore associations between AD completion and each outcome. Of the 1031 patients who received allogeneic HCT during the study period, 422 decedents (41%) were included in the analysis. Forty-four percent had AD documentation prior to death. Most patients (69%) indicated that if terminally ill, they did not wish to be subjected to life-prolonging treatment attempts. Race/ethnicity was significantly associated with AD documentation, with non-Hispanic white patients documenting ADs more frequently (51%) compared with Hispanic (22%) or Asian patients (35%; P = .0007). Patients with ADs were less likely to use the ICU during the transplant course (41% for patients with ADs versus 52% of patients without ADs; P = .03) and also were less likely to receive mechanical ventilation at any point after transplantation (21% versus 37%, P < .001). AD documentation was also associated with decreased ICU use at the end of life; relative to patients without ADs, patients with ADs were more likely to die at home or in hospital as opposed to in the ICU (odds ratio, .44; 95% confidence interval, .27 to .72). ACP remains underused in allogeneic HCT. Adoption of a systematic practice to standardize AD documentation as part of allogeneic HCT planning has the potential to significantly reduce ICU use and mechanical ventilation while improving quality of care at end of life in HCT recipients.

An Antibacterial ß-Lactone Kills Mycobacterium tuberculosis by Disrupting Mycolic Acid Biosynthesis.

The spread of antibiotic resistance is a major challenge for the treatment of Mycobacterium tuberculosis infections. In addition, the efficacy of drugs is often limited by the restricted permeability of the mycomembrane. Frontline antibiotics inhibit mycomembrane biosynthesis, leading to rapid cell death. Inspired by this mechanism, we exploited ß-lactones as putative mycolic acid mimics to block serine hydrolases involved in their biosynthesis. Among a collection of ß-lactones, we found one hit with potent anti-mycobacterial and bactericidal activity. Chemical proteomics using an alkynylated probe identified Pks13 and Ag85 serine hydrolases as major targets. Validation through enzyme assays and customized 13 C metabolite profiling showed that both targets are functionally impaired by the ß-lactone. Co-administration with front-line antibiotics enhanced the potency against M. tuberculosis by more than 100-fold, thus demonstrating the therapeutic potential of targeting mycomembrane biosynthesis serine hydrolases.

Cleavage Specificity of Mycobacterium tuberculosis ClpP1P2 Protease and Identification of Novel Peptide Substrates and Boronate Inhibitors with Anti-bacterial Activity.

The ClpP1P2 protease complex is essential for viability in Mycobacteria tuberculosis and is an attractive drug target. Using a fluorogenic tripeptide library (Ac-X3X2X1-aminomethylcoumarin) and by determining specificity constants (kcat/Km), we show that ClpP1P2 prefers Met ≫ Leu > Phe > Ala in the X1 position, basic residues or Trp in the X2 position, and Pro ≫ Ala > Trp in the X3 position. We identified peptide substrates that are hydrolyzed up to 1000 times faster than the standard ClpP substrate. These positional preferences were consistent with cleavage sites in the protein GFPssrA by ClpXP1P2. Studies of ClpP1P2 with inactive ClpP1 or ClpP2 indicated that ClpP1 was responsible for nearly all the peptidase activity, whereas both ClpP1 and ClpP2 contributed to protein degradation. Substrate-based peptide boronates were synthesized that inhibit ClpP1P2 peptidase activity in the submicromolar range. Some of them inhibited the growth of Mtb cells in the low micromolar range indicating that cleavage specificity of Mtb ClpP1P2 can be used to design novel anti-bacterial agents.

Post-translational regulation via Clp protease is critical for survival of Mycobacterium tuberculosis.

Unlike most bacterial species, Mycobacterium tuberculosis depends on the Clp proteolysis system for survival even in in vitro conditions. We hypothesized that Clp is required for the physiologic turnover of mycobacterial proteins whose accumulation is deleterious to bacterial growth and survival. To identify cellular substrates, we employed quantitative proteomics and transcriptomics to identify the set of proteins that accumulated upon the loss of functional Clp protease. Among the set of potential Clp substrates uncovered, we were able to unambiguously identify WhiB1, an essential transcriptional repressor capable of auto-repression, as a substrate of the mycobacterial Clp protease. Dysregulation of WhiB1 turnover had a toxic effect that was not rescued by repression of whiB1 transcription. Thus, under normal growth conditions, Clp protease is the predominant regulatory check on the levels of potentially toxic cellular proteins. Our findings add to the growing evidence of how post-translational regulation plays a critical role in the regulation of bacterial physiology.

Pendrin localizes to the adrenal medulla and modulates catecholamine release.

Pendrin (Slc26a4) is a Cl(-)/HCO3 (-) exchanger expressed in renal intercalated cells and mediates renal Cl(-) absorption. With pendrin gene ablation, blood pressure and vascular volume fall, which increases plasma renin concentration. However, serum aldosterone does not significantly increase in pendrin-null mice, suggesting that pendrin regulates adrenal zona glomerulosa aldosterone production. Therefore, we examined pendrin expression in the adrenal gland using PCR, immunoblots, and immunohistochemistry. Pendrin protein was detected in adrenal lysates from wild-type but not pendrin-null mice. However, immunohistochemistry and qPCR of microdissected adrenal zones showed that pendrin was expressed in the adrenal medulla, rather than in cortex. Within the adrenal medulla, pendrin localizes to both epinephrine- and norepinephrine-producing chromaffin cells. Therefore, we examined plasma catecholamine concentration and blood pressure in wild-type and pendrin-null mice under basal conditions and then after 5 and 20 min of immobilization stress. Under basal conditions, blood pressure was lower in the mutant than in the wild-type mice, although epinephrine and norepinephrine concentrations were similar. Catecholamine concentration and blood pressure increased markedly in both groups with stress. With 20 min of immobilization stress, epinephrine and norepinephrine concentrations increased more in pendrin-null than in wild-type mice, although stress produced a similar increase in blood pressure in both groups. We conclude that pendrin is expressed in the adrenal medulla, where it blunts stress-induced catecholamine release.

Leukemic infiltration of the optic nerve in chronic lymphocytic leukemia: A case report and review of literature.

Ophthalmic and neurologic involvement are rare complications of CLL, with few cases reported in the literature. We report a case of CLL with leukemic infiltration of the optic nerve and review of literature focusing on management and outcomes. A patient with heavily pretreated CLL presented to our hospital with progressive eye pain and was found to have infiltrative optic neuritis. CSF analysis confirmed involvement with CLL. After systemic treatment with R-CHOP and high-dose methotrexate, along with intrathecal cytarabine and hydrocortisone, she experienced significant improvement and was discharged home. Given the rarity of ophthalmic involvement in CLL, we reviewed all 15 previously reported cases of CLL with optic neuropathy as the first manifestation of CNS involvement and discussed the range of treatment options used and their respective outcomes.

Gliotransmission of D-serine promotes thirst-directed behaviors in Drosophila.

Thirst emerges from a range of cellular changes that ultimately motivate an animal to consume water. Although thirst-responsive neuronal signals have been reported, the full complement of brain responses is unclear. Here, we identify molecular and cellular adaptations in the brain using single-cell sequencing of water-deprived Drosophila. Water deficiency primarily altered the glial transcriptome. Screening the regulated genes revealed astrocytic expression of the astray-encoded phosphoserine phosphatase to bi-directionally regulate water consumption. Astray synthesizes the gliotransmitter D-serine, and vesicular release from astrocytes is required for drinking. Moreover, dietary D-serine rescues aay-dependent drinking deficits while facilitating water consumption and expression of water-seeking memory. D-serine action requires binding to neuronal NMDA-type glutamate receptors. Fly astrocytes contribute processes to tripartite synapses, and the proportion of astrocytes that are themselves activated by glutamate increases with water deprivation. We propose that thirst elevates astrocytic D-serine release, which awakens quiescent glutamatergic circuits to enhance water procurement.

A phase II trial of gemcitabine and erlotinib followed by ChemoProton therapy plus capecitabine and oxaliplatin for locally advanced pancreatic cancer.

Background: Epidermal growth factor receptor (EGFR) is overexpressed in pancreatic cancer. EGFR expression plays a potentially important role in modulation of tumor sensitivity to either chemotherapy or radiotherapy. Erlotinib is a receptor tyrosine kinase inhibitor with specificity for EGFR/HER1. A phase II trial was conducted to explore the efficacy of a regimen utilizing erlotinib and proton therapy. Methods: Patients with unresectable or borderline resectable non-metastatic adenocarcinoma of the pancreas were included. Patients received 8-week systemic treatment with gemcitabine 1,000 mg/m2 and erlotinib 100 mg (GE). If there was no evidence of metastatic disease after GE, then patients preceded with proton therapy to 50.4 Gy in 28 fractions with concurrent capecitabine 825 mg/m2 (CPT). This was followed with oxaliplatin 130 mg/m2 and capecitabine 1,000 mg/m2 (CapOx) for 4 cycles. The primary study objective was 1-year overall survival (OS). The benchmark was 43% 1-year survival as demonstrated in RTOG/NRG 98-12. The Kaplan-Meier method was used to estimate the one-year OS and the median OS and progression-free survival (PFS). Results: The study enrolled 9 patients ages 47-81 years old (median 62) between January 2013 and March 2016, when the trial was closed due to low patient accrual. The 1-year OS rate was 55.6% (95% CI: 31% to 99%). The median OS was 14.1 months (95% CI: 11.4-NE) and the median PFS was 10.8 months (95% CI: 7.44-NE). A majority of patients completed CPT and GE, but only 33.3% completed the four cycles of CapOx. A third of patients experienced grade 3 toxicities, which were all hepatic along with one patient who also had grade 3 diarrhea. There were no grade 4 or 5 toxicities. Four patients were enrolled with borderline resectable disease, three of which were eligible for pancreaticoduodenectomy after GE and CPT treatment. One of two patients who underwent resection had a negative margin. Conclusions: This regimen for locally advanced pancreatic cancer (LAPC) exceeded the pre-specified benchmark and was safe and well tolerated. Additional investigations utilizing more current systemic treatment regimens with proton therapy are warranted. Trial Registration: ClinicalTrials.gov identifier (NCTNCT01683422).

Alcohol potentiates a pheromone signal in flies.

For decades, numerous researchers have documented the presence of the fruit fly or Drosophila melanogaster on alcohol-containing food sources. Although fruit flies are a common laboratory model organism of choice, there is relatively little understood about the ethological relationship between flies and ethanol. In this study, we find that when male flies inhabit ethanol-containing food substrates they become more aggressive. We identify a possible mechanism for this behavior. The odor of ethanol potentiates the activity of sensory neurons in response to an aggression-promoting pheromone. Finally, we observed that the odor of ethanol also promotes attraction to a food-related citrus odor. Understanding how flies interact with the complex natural environment they inhabit can provide valuable insight into how different natural stimuli are integrated to promote fundamental behaviors.

Glycemic Control in Adult Surgical Patients Receiving Regular Insulin Added to Parenteral Nutrition vs Insulin Glargine: A Retrospective Chart Review.

BACKGROUND: Hyperglycemia is a frequent complication in patients receiving parenteral nutrition (PN) and has been associated with an increased risk of mortality. Treatment of hyperglycemia requires insulin therapy; however, the optimal dose and route have not been established. This study aimed to compare regular insulin added to PN (RI-in-PN) with subcutaneous insulin glargine for the management of hyperglycemia in patients receiving PN. METHODS: This retrospective study was conducted at a tertiary medical center and reviewed 113 adult, non-critically ill surgical patient admissions receiving PN over a 5-year period. The primary outcome was achievement of glycemic control. Secondary outcomes were time to glycemic control, hypoglycemic events, hospital length of stay, and 1-year mortality. RESULTS: The RI-in-PN group had a significantly higher percentage of patient admissions who achieved glycemic control compared with the insulin glargine group (71.8% vs 48.6%, P = 0.017). There was no difference in time to glycemic control, hypoglycemic events, hospital length of stay, or 1-year mortality between groups. Among patients with diabetes mellitus (DM), however, the insulin glargine group had a significantly higher percentage of admissions with at least 1 hypoglycemic event (45.5% vs 20%, P = 0.035). CONCLUSIONS: RI-in-PN is recommended over insulin glargine because of the higher likelihood of achieving glycemic control and, in patients with DM, lower risk of hypoglycemic events. Large, randomized controlled trials are needed to further guide prescribing practice.

Blood collection in unstressed, conscious, and freely moving mice through implantation of catheters in the jugular vein: a new simplified protocol.

The mouse has become the most common mammalian animal model used in biomedical research. However, laboratory techniques used previously in rats and other larger animals to sample blood had to be adapted in mice due to their lower mouse plasma volume. Sampling is further confounded by the variability in plasma hormone and metabolite concentrations that can occur from the stress or the anesthesia that accompanies the collection. In this article, we describe in detail a protocol we developed for blood sampling in conscious, unrestrained mice. Our protocol implements the use of chronic indwelling catheters in the right external jugular vein, allowing the mice to recover fully in their home cages, untethered until the time of blood sampling. This protocol employs catheters that remain patent for days and does not require the purchase of expensive equipment. We validated this protocol by measuring the time course of plasma norepinephrine (NE) concentration during and after the relief of acute immobilization stress in wild type (WT) and pendrin knockout (KO) mice and compared these results with our previously published values. We found that following relief from immobilization stress, it takes longer for plasma NE concentration to return to basal levels in the pendrin KO than in the wild type mice. These results highlight the potential utility of this protocol and the potential role of pendrin in the neuroendocrine response to acute stress.