) for measuring NE, the George F. O'Brien Center, University of Alabama (P30DK079337; principal investigator, Anupam Agarwal) for measuring plasma creatinine by LC-MS, the UVA Research Histology Core for their assistance in preparation of histology slides, and the UVA Flow Cytometry Facility for sample analysis using the Luminex 100 IS system and FACS sorting using BD Influx. We also thank Primetech Corp. (Tokyo, Japan) for supplying the iPRECIO microinfusion pump system.

C1 neurons (C1), located in the medulla oblongata, mediate adaptive autonomic responses to physical stressors (e.g. hypotension, hemorrhage, lipopolysaccharide). We describe here a powerful effect of restraint stress mediated by C1: protection against renal ischemia-reperfusion injury (IRI).Restraint stress or optogenetic C1 stimulation (10 min) protected mice from IRI. The protection was reproduced by injecting splenic T-cells pre-incubated with noradrenaline or splenocytes harvested from stressed mice. Stress-induced IRI protection was absent in α7nAChR−/− mice and greatly reduced by destroying or transiently inhibiting C1. The protection conferred by C1 stimulation was eliminated by splenectomy, ganglionic blocker administration, or β2-adrenergic receptor blockade. Although C1 stimulation elevated plasma corticosterone and increased both vagal and sympathetic nerve activity, C1-mediated IRI protection persisted after subdiaphragmatic vagotomy or corticosterone receptor blockade.In conclusion, acute stress attenuates IRI by activating a cholinergic, predominantly sympathetic, anti-inflammatory pathway. C1 neurons are necessary and sufficient to mediate this effect.

The activity of background potassium and sodium channels determines neuronal excitability, but physiological roles for "leak" Na ϩ channels in specific mammalian neurons have not been established. Here, we show that a leak Na ϩ channel, Nalcn, is expressed in the CO 2 /H ϩ -sensitive neurons of the mouse retrotrapezoid nucleus (RTN) that regulate breathing. In RTN neurons, Nalcn expression correlated with higher action potential discharge over a more alkalized range of activity; shRNA-mediated depletion of Nalcn hyperpolarized RTN neurons, and reduced leak Na ϩ current and firing rate. Nalcn depletion also decreased RTN neuron activation by the neuropeptide, substance P, without affecting pH-sensitive background K ϩ currents or activation by a cotransmitter, serotonin. In vivo, RTN-specific knockdown of Nalcn reduced CO 2 -evoked neuronal activation and breathing; hypoxic hyperventilation was unchanged. Thus, Nalcn regulates RTN neuronal excitability and stimulation by CO 2 , independent of direct pH sensing, potentially contributing to respiratory effects of Nalcn mutations; transmitter modulation of Nalcn may underlie state-dependent changes in breathing and respiratory chemosensitivity.

Current understanding of the contribution of C1 neurons to blood pressure (BP) regulation derives predominantly from experiments performed in anesthetized animals or reduced ex vivo preparations. Here, we use ArchaerhodopsinT3.0 (ArchT) loss-of-function optogenetics to explore BP regulation by C1 neurons in intact, unanesthetized rats. Using a lentivirus that expresses ArchT under the Phox2b-activated promoter PRSx8 (PRSx8-ArchT), ϳ65% of transduced neurons were C1 (balance retrotrapezoid nucleus, RTN). Other rats received CaMKII-ArchT3.0 AAV2 (CaMKII-ArchT), which transduced C1 neurons and larger numbers of unidentified glutamatergic and GABAergic cells. Under anesthesia, ArchT photoactivation reduced sympathetic nerve activity and BP and silenced/strongly inhibited most (7/12) putative C1 neurons. In unanesthetized PRSx8-ArchT-treated rats breathing room air, bilateral ArchT photoactivation caused a very small BP reduction that was only slightly larger under hypercapnia (6% FiCO 2 ), but was greatly enhanced during hypoxia (10 and 12% FiO 2 ), after sino-aortic denervation, or during isoflurane anesthesia. The degree of hypotension correlated with percentage of ArchT-transduced C1 neurons. ArchT photoactivation produced similar BP changes in CaMKII-ArchT-treated rats. Photoactivation in PRSX8-ArchT rats reduced breathing frequency (F R ), whereas F R increased in CaMKII-ArchT rats. We conclude that the BP drop elicited by ArchT activation resulted from C1 neuron inhibition and was unrelated to breathing changes. C1 neurons have low activity under normoxia, but their activation is important to BP stability during hypoxia or anesthesia and contributes greatly to the hypertension caused by baroreceptor deafferentation. Finally, C1 neurons are marginally activated by hypercapnia and the large breathing stimulation caused by this stimulus has very little impact on resting BP.

A new bacterial copolyester of 3-hydroxyhexanoate (HH), 3-hydroxyoctanoate (HO), 3-hydroxy-6-chlorohexanoate (HCH), and 3-hydroxy-8-chlorooctanoate (HCO) units was synthesized in Pseudomonas oleovorans by using octane and 1-chlorooctane as the carbon sources. The copolyester (Mn = 87 000, Mw = 201 000) was shown to have a random sequence distribution of four different monomeric units by analysis of the 125-MHz 13C NMR spectrum.

Exposure to a hypergravity environment induces acute transient hypophagia, which is partially restored by a vestibular lesion (VL), suggesting that the vestibular system is involved in the afferent pathway of hypergravity-induced hypophagia. When rats were placed in a 3-G environment for 14 days, Fos-containing cells increased in the paraventricular hypothalamic nucleus, the central nucleus of the amygdala, the medial vestibular nucleus, the raphe nucleus, the nucleus of the solitary tract, and the area postrema. The increase in Fos expression was completely abolished or significantly suppressed by VL. Therefore, these regions may be critical for the initiation and integration of hypophagia. Because the vestibular nucleus contains serotonergic neurons and because serotonin (5-HT) is a key neurotransmitter in hypophagia, with possible involvement in motion sickness, we hypothesized that central 5-HT increases during hypergravity and induces hypophagia. To examine this proposition, the 5-HT concentrations in the cerebrospinal fluid were measured when rats were reared in a 3-G environment for 14 days. The 5-HT concentrations increased in the hypergravity environment, and these increases were completely abolished in rats with VL. Furthermore, a 5-HT(2A) antagonist (ketanserin) significantly reduced 3-G (120 min) load-induced Fos expression in the medial vestibular nucleus, and chronically administered ketanserin ameliorated hypergravity-induced hypophagia. These results indicate that hypergravity induces an increase in central 5-HT via the vestibular input and that this increase plays a significant role in hypergravity-induced hypophagia. The 5-HT(2A) receptor is involved in the signal transduction of hypergravity stress in the vestibular nucleus.

Acute kidney injury is highly prevalent and associated with high morbidity and mortality, and there are no approved drugs for its prevention and treatment. Vagus nerve stimulation (VNS) alleviates inflammatory diseases including kidney disease; however, neural circuits involved in VNS-induced tissue protection remain poorly understood. The vagus nerve, a heterogeneous group of neural fibers, innervates numerous organs. VNS broadly stimulates these fibers without specificity. We used optogenetics to selectively stimulate vagus efferent or afferent fibers. Anterograde efferent fiber stimulation or anterograde (centripetal) sensory afferent fiber stimulation both conferred kidney protection from ischemia–reperfusion injury. We identified the C1 neurons–sympathetic nervous system–splenic nerve–spleen–kidney axis as the downstream pathway of vagus afferent fiber stimulation. Our study provides a map of the neural circuits important for kidney protection induced by VNS, which is critical for the safe and effective clinical application of VNS for protection from acute kidney injury.

To elucidate the pure impact of microgravity on small mammals despite uncontrolled factors that exist in the International Space Station, it is necessary to construct a 1 g environment in space. The Japan Aerospace Exploration Agency has developed a novel mouse habitat cage unit that can be installed in the Cell Biology Experiment Facility in the Kibo module of the International Space Station. The Cell Biology Experiment Facility has a short-arm centrifuge to produce artificial 1 g gravity in space for mouse experiments. However, the gravitational gradient formed inside the rearing cage is larger when the radius of gyration is shorter; this may have some impact on mice. Accordingly, biological responses to hypergravity induced by a short-arm centrifuge were examined and compared with those induced by a long-arm centrifuge. Hypergravity induced a significant Fos expression in the central nervous system, a suppression of body mass growth, an acute and transient reduction in food intake, and impaired vestibulomotor coordination. There was no difference in these responses between mice raised in a short-arm centrifuge and those in a long-arm centrifuge. These results demonstrate the feasibility of using a short-arm centrifuge for mouse experiments.