bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiovascular and renal sympathetic activation by blood-borne TNF-α in rat: the role of central prostaglandins
Authors: Zhang Zhi-Hua , Wei Shun-Guang , Francis Joseph , Felder Robert B.
Published: March 2015

In pathophysiological conditions, increased blood-borne TNF-α induces a broad range of biological effects, including activation of the hypothalamic-pituitary-adrenal axis and sympathetic drive. In urethane-anesthetized adult Sprague-Dawley rats, we examined the mechanisms by which blood-borne TNF-α activates neurons in paraventricular nucleus (PVN) of hypothalamus and rostral ventrolateral medulla (RVLM), two critical brain regions regulating sympathetic drive in normal and pathophysiological conditions. TNF-α (0.5 μg/kg), administered intravenously or into ipsilateral carotid artery (ICA), activated PVN and RLVM neurons and increased sympathetic nerve activity, arterial pressure, and heart rate. Responses to intravenous TNF-α were not affected by vagotomy but were reduced by mid-collicular decerebration. Responses to ICA TNF-α were substantially reduced by injection of the cyclooxygenase inhibitor ketorolac (150 μg) into lateral ventricle. Injection of PGE2 (50 ng) into lateral ventricle or directly into PVN increased PVN or RVLM activity, respectively, and sympathetic drive, with shorter onset latency than blood-borne TNF-α. These findings suggest that blood-borne cytokines stimulate cardiovascular and renal sympathetic responses via a prostaglandin-dependent mechanism operating at the hypothalamic level.
Unequal autonegative feedback by GH models the sexual dimorphism in GH secretory dynamics
Authors: Farhy Leon S. , Straume Martin , Johnson Michael L. , Kovatchev Boris , Veldhuis Johannes D.
Published: March 2015

Growth hormone (GH) secretion, controlled principally by a GH-releasing hormone (GHRH) and GH release-inhibiting hormone [somatostatin (SRIF)] displays vivid sexual dimorphism in many species. We hypothesized that relatively small differences within a dynamic core GH network driven by regulatory interactions among GH, GHRH, and SRIF explain the gender contrast. To investigate this notion, we implemented a minimal biomathematical model based on two coupled oscillators: time-delayed reciprocal interactions between GH and GHRH, which endow high-frequency (40–60 min) GH oscillations, and time-lagged bidirectional GH-SRIF interactions, which mediate low-frequency (occurring every 3.3 h) GH volleys. We show that this basic formulation, sufficient to explain GH dynamics in the male rat [Farhy LS, Straume M, Johnson ML, Kovatchev BP, and Veldhuis JD. Am J Physiol Regulatory Integrative Comp Physiol 281: R38–R51, 2001], emulates the female pattern of GH release, if autofeedback of GH on SRIF is relaxed. Relief of GH-stimulated SRIF release damps the slower volleylike oscillator, allowing emergence of the underlying high-frequency oscillations that are sustained by the GH-GHRH interactions. Concurrently, increasing variability of basal somatostatin outflow introduces quantifiable, sex-specific disorderliness of the release process typical of female GH dynamics. Accordingly, modulation of GH autofeedback on SRIF within the interactive GH-GHRH-SRIF ensemble and heightened basal SRIF variability are sufficient to transform the well-ordered, 3.3-h-interval, multiphasic, volleylike male GH pattern into a femalelike profile with irregular pulses of higher frequency.
Heat acclimation in rats: modulation via lipid polyunsaturation
Authors: Shmeeda Hilary , Kaspler Pavel , Shleyer Judith , Honen Reuma , Horowitz Michal , Barenholz Yechezkel
Published: March 2015

Heat acclimation of rats has been shown to enhance endurance of rat hearts to ischemic insult and acute heat stress. Common protective features have been shown to be operative during both these stress-inducing conditions. To explore the role of membrane lipid composition in the adaptive response, we analyzed two major parameters that impact membrane dynamics and order, the nonesterified cholesterol levels and the acyl chain composition of phospholipids, in rat heart and salivary glands, both major thermoregulatory organs, in short- and long-term heat-acclimated rats. Before exposure to heat, control salivary gland tissue has a higher cholesterol-to-phospholipid mole ratio (0.32 ± 0.02) than heart (0.14 ± 0.01), and the acyl chains of its phospholipids are 50% more saturated. The remodeling strategies of the tissues after exposure to heat differed. Heart cholesterol levels increased after short-term heat acclimation (∼50%), whereas salivary gland cholesterol levels decreased in acute heat stress and long-term heat acclimation (∼32%). Remodeling of phospholipid acyl chains, particularly an increase in docosahexaenoic acid, was a protective strategy in both tissues (57% in heart and >100% in salivary glands). Modifying membrane lipid composition by treating rats with liposomes composed of egg phosphatidylcholine (PC) before exposure to heat resulted in a 38% increase in endurance to thermal stress. The density and affinity of muscarinic receptors of submaxillary salivary glands, involved in the acclimation response, were measured in control and PC liposome-treated rats, and then both groups were subjected to short-term heat acclimation. After PC treatment the well-established compensatory upregulation of the muscarinic receptors and concomitant decrease in their affinity was blunted. The substantial increase in the thermal endurance of heat-challenged intact rats after treatment with PC liposomes (600 vs. 200 min) suggests that membrane lipid composition plays a role in the ability of these tissues to respond to heat stress.
Trefoil peptide expression and goblet cell number in rat intestine: effects of KGF and fasting-refeeding
Authors: Fernández-Estívariz Concepción , Gu Li H. , Gu Liang , Jonas Carolyn R. , Wallace Timothy M. , Pascal Robert R. , Devaney Kathryn L. , Farrell Catherine L. , Jones Dean P. , Podolsky Daniel K. , Ziegler Thomas R.
Published: March 2015

The trefoil factor family peptides TFF1, TFF2, and TFF3 are important for gut mucosal protection and restitution. Keratinocyte growth factor (KGF) stimulates proliferation and differentiation of epithelial cells with potent effects on goblet cells. To investigate interactions between food intake and KGF, rats were fed ad libitum (control), fasted for 72 h, or fasted for 72 h and then refed for 72 h with or without KGF (3 mg · kg−1· day−1). With fasting, goblet cell number in duodenum increased, TFF3 mRNA in duodenum and jejunum decreased, and TFF3 protein did not change or increased. KGF during fasting stimulated colonic growth, normalized TFF3 mRNA in duodenum and jejunum, and broadly upregulated gut goblet cell number and TFF3 protein expression. With fasting-refeeding, KGF increased small bowel and colonic mucosal growth, goblet cell number, and TFF3 protein but had variable effects on TFF3 mRNA. KGF induced TFF2 mRNA and protein in duodenum and jejunum with both nutritional regimens. We conclude that nutrient availability modifies rat intestinal goblet cell number, TFF3 mRNA, and the gut-trophic effects of KGF in a region-specific manner. KGF enhances TFF2 expression in proximal small bowel and increases goblet cell number and TFF3 protein content throughout the intestine independent of food intake.
Neuropeptide Y effects on vasorelaxation and intestinal contraction in the Atlantic cod Gadus morhua
Authors: Shahbazi Fatemeh , Holmgren Susanne , Larhammar Dan , Jensen Jörgen
Published: March 2015

Neuropeptide Y (NPY) has prominent cardiovascular effects in mammals and sharks, but no such effect has previously been demonstrated in any teleost fish. In the Atlantic cod, we found that cod NPY (10−10–10−6 M) relaxed celiac arteries precontracted with epinephrine, and weak contractions were elicited in intestinal ring preparations. A few NPY-immunoreactive nerve fibers were present along small gut arteries. The results suggest that cod NPY produces vasorelaxation both by a direct action on smooth muscle and by release of prostaglandins, but with no involvement of nitric oxide, leukotrienes, or endothelium-derived relaxing factors. An additional indirect effect involving another neurotransmitter may occur. Cod NPY (10−7 M) and human NPY (10−7 M) had identical effects on the vessels. Small differences only in the effects of porcine [Leu31,Pro34]NPY, NPY-(13–36), and cod NPY suggest the presence of a Y1 subfamily receptor, similar to the zebrafish Ya receptor. A physiological role for NPY in teleost vasculature is concluded, but surprisingly the effect, a vasodilation, is opposite to that in mammals and is mediated by prostaglandins.
Urocortin in the hypothalamic PVN increases leptin and affects uncoupling proteins-1 and -3 in rats
Authors: Kotz Catherine M. , Wang Chuanfeng , Levine Allen S. , Billington Charles J.
Published: March 2015

The hypothalamic paraventricular nucleus (PVN) plays a primary role in energy homeostasis, and urocortin (UCN) decreases feeding after injection into the PVN. Peripheral uncoupling proteins (UCPs) may influence energy metabolism. The effect of UCN administered into the PVN on UCPs is unknown. We injected PVN-cannulated rats with either UCN (200 pmol) or artificial cerebrospinal fluid (aCSF) at 0800, 2000, and again at 0800. An aCSF-injected group with food intake restricted to the level of UCN-treated animals was included to control for decreased feeding in the UCN-treated rats. Two hours after the final set of injections, rats were killed, and white adipose tissue, brown adipose tissue, and biceps femoris and acromiotrapezius muscle tissues were taken for analysis of UCP-1, -2, and -3. Trunk blood was collected for measurement of plasma leptin. Relative to food-restricted control animals, UCN in the PVN significantly increased plasma leptin and UCP-1 mRNA in brown adipose tissue and decreased UCP-3 mRNA in acromiotrapezius muscle, suggesting a role for PVN UCN in the regulation of energy balance.
Mechanisms regulating the marked seasonal variation in melatonin synthesis in the European hamster pineal gland
Authors: Garidou Marie-Laure , Vivien-Roels Berthe , Pévet Paul , Miguez Jesus , Simonneaux Valérie
Published: March 2015

Like many wild species, the European hamster ( Cricetus cricetus) adapts to the marked seasonal changes in its environment, namely by hibernation and inhibition of sexual activity in winter. These annual functions are driven by the variation in the environmental factors (light, temperature) that are transmitted to the body through large variations in the duration and amplitude of the nocturnal melatonin rhythm. Here we report that the seasonal variation in melatonin synthesis is mainly driven by arylalkylamine N-acetyltransferase gene transcription and enzyme activation. This, however, does not exclude participation of hydroxyindole- O-methyltransferase, which may relay environmental temperature information. The in vivo experiments show that norepinephrine stimulates melatonin synthesis, this effect being gated at night. The possibility that the variation in pineal metabolism depends on a seasonal change in the suprachiasmatic nuclei clock circadian activity that is transmitted by norepinephrine is discussed.
Direct interstitial infusion of NK1-targeted neurotoxin into the spinal cord: a computational model
Authors: Sarntinoranont Malisa , Iadarola Michael J. , Lonser Russell R. , Morrison Paul F.
Published: March 2015

Convection-enhanced delivery of substance P (SP) nocitoxins to the spinal cord interstitium is under consideration for the treatment of chronic pain. To characterize treatment protocols, a three-dimensional finite-element model of infusion into the human dorsal column was developed to predict the distribution of SP-diphtheria toxin fusion protein (SP-DT′) within normal and target tissue. The model incorporated anisotropic convective and diffusive transport through the interstitial space, hydrolysis by peptidases, and intracellular trafficking. For constant SP-DT′ infusion (0.1 μl/min), the distribution of cytotoxicity in NK1receptor-expressing neurons was predicted to reach an asymptotic limit at 6–8 h in the transverse direction at the level of the infusion cannula tip (∼60% ablation of target neurons in lamina I/II). Computations revealed that SP-DT′ treatment was favored by a stable SP analog (half-life ∼60 min), high infusate concentration (385 nM), and careful catheter placement (adjacent to target lamina I/II). Sensitivity of cytotoxic regions to NK1receptor density and white matter protease activity was also established. These data suggest that intraparenchymal infusions can be useful for treatment of localized chronic pain.
Circadian phase-delaying effects of bright light alone and combined with exercise in humans
Authors: Youngstedt Shawn D. , Kripke Daniel F. , Elliott Jeffrey A.
Published: March 2015

In a within-subjects ( n= 18), counterbalanced design, the circadian phase-shifting effects of 3 h of 1) bright light (3,000 lx) alone 2) and bright light combined with vigorous exercise were compared. For each treatment, volunteers spent 3 nights and 2 days in the laboratory, typically receiving the treatment from ∼2300 to 0200 on night 2. Bedtimes and waketimes were fixed to the volunteers' habits. Illumination was 50 lx during other wake hours and 0 lx during sleep. Bright Light Alone elicited a significant phase delay in rectal temperature minimum (70 min), but not in urinary 6-sulphatoxymelatonin (6-SMT) acrophase (20 min). Bright Light + Exercise elicited a significant phase delay in 6-SMT (68 min), but did not result in a significant difference in shift compared with Bright Light Alone. The study had adequate statistical power (80%) to detect phase-shift differences between treatments of ∼2–2.5 h. Thus any antagonism of light shifts with exercise could not have been revealed. Within the limited exercise and light parameters of this study, the results suggest that exercise does not reliably modulate phase-shifting effects of late night bright light in humans.
Mechanisms for maintaining extracellular glutamate levels in the anoxic turtle striatum
Authors: Milton Sarah L. , Thompson John W. , Lutz Peter L.
Published: March 2015

The turtle Trachemys scriptais one of a limited group of vertebrates that can withstand hours to days without oxygen. One facet of anoxic survival is the turtle's ability to maintain basal extracellular glutamate levels, whereas in most vertebrates, anoxia triggers massive excitotoxic glutamate release. We investigated glutamate release and reuptake in the anoxic turtle and the effects of adenosine and ATP-sensitive potassium (KATP) channels on glutamate homeostasis. Striatal extracellular glutamate was measured in anesthetized T. scripta by microdialysis in normoxia and over 2-h anoxia. Glutamate release is decreased by 44% in the early anoxic turtle; this anoxia-induced decrease in glutamate release was prevented when KATPchannels and adenosine receptors were blocked simultaneously but not when either mechanism was blocked individually. We hypothesize that the continued release and reuptake of glutamate during anoxia help maintain neuronal tone and aid in the recovery of a functional neuronal network after long periods of anoxia, whereas activation of adenosine and/or KATPconserves energy by reducing glutamate release and lowering transport costs.
Effects of peripheral CCK receptor blockade on gastric emptying in rats
Authors: Reidelberger Roger D. , Kelsey Linda , Heimann Dean , Hulce Martin
Published: March 2015

Type A CCK receptor (CCKAR) antagonists differing in blood-brain barrier permeability [devazepide penetrates; the dicyclohexylammonium salt of Nα-3-quinolinoyl-d-Glu- N,N-dipentylamide (A-70104) does not] were used to test the hypothesis that duodenal nutrient-induced inhibition of gastric emptying is mediated by CCKARs located peripheral to the blood-brain barrier. Rats received A-70104 (700 or 3,000 nmol · kg−1· h−1iv) or devazepide (2.5 μmol/kg iv) and either a 15-min intravenous infusion of CCK-8 (3 nmol · kg−1· h−1) or duodenal infusion of casein, peptone, Intralipid, or maltose. Gastric emptying of saline was measured during the last 5 min of each infusion. A-70104 and devazepide abolished the gastric emptying response to a maximal inhibitory dose of CCK-8. Each of the macronutrients inhibited gastric emptying. A-70104 and devazepide attenuated inhibitory responses to each macronutrient. Intravenous injection of a CCK antibody to immunoneutralize circulating CCK had no effect on peptone or Intralipid-induced responses. Thus endogenous CCK appears to act in part by a paracrine or neurocrine mechanism at CCKARs peripheral to the blood-brain barrier to inhibit gastric emptying.
Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance
Authors: Liu Huang-Ku , Guild Sarah-Jane , Ringwood John V. , Barrett Carolyn J. , Leonard Bridget L. , Nguang Sing-Kiong , Navakatikyan Michael A. , Malpas Simon C.
Published: March 2015

The aim in the present experiments was to assess the dynamic baroreflex control of blood pressure, to develop an accurate mathematical model that represented this relationship, and to assess the role of dynamic changes in heart rate and stroke volume in giving rise to components of this response. Patterned electrical stimulation [pseudo-random binary sequence (PRBS)] was applied to the aortic depressor nerve (ADN) to produce changes in blood pressure under open-loop conditions in anesthetized rabbits. The stimulus provided constant power over the frequency range 0–0.5 Hz and revealed that the composite systems represented by the central nervous system, sympathetic activity, and vascular resistance responded as a second-order low-pass filter (corner frequency ≈0.047 Hz) with a time delay (1.01 s). The gain between ADN and mean arterial pressure was reasonably constant before the corner frequency and then decreased with increasing frequency of stimulus. Although the heart rate was altered in response to the PRBS stimuli, we found that removal of the heart's ability to contribute to blood pressure variability by vagotomy and β1-receptor blockade did not significantly alter the frequency response. We conclude that the contribution of the heart to the dynamic regulation of blood pressure is negligible in the rabbit. The consequences of this finding are examined with respect to low-frequency oscillations in blood pressure.
Postexercise α-adrenergic receptor hyporesponsiveness in hypertensive rats is due to nitric oxide
Authors: Rao Sumangala P. , Collins Heidi L. , DiCarlo Stephen E.
Published: March 2015

We tested the hypothesis that a single bout of dynamic exercise produces a postexercise hypotension (PEH) and α1-adrenergic receptor hyporesponsiveness in spontaneously hypertensive rats (SHR). The postexercise α1-adrenergic receptor hyporesponsiveness is due to an enhanced buffering of vasoconstriction by nitric oxide. Male ( n = 8) and female ( n = 5) SHR were instrumented with a Doppler ultrasonic flow probe around the femoral artery. Distal to the flow probe, a microrenathane catheter was inserted into a branch of the femoral artery for the infusion of the α1-adrenergic receptor agonist phenylephrine (PE). A microrenathane catheter was inserted into the descending aorta via the left common carotid artery for measurements of arterial pressure (AP) and heart rate. Dose-response curves to PE (3.8 × 10−3− 1.98 × 10−2μg/kHz) were generated before and after a single bout of dynamic exercise. Postexercise AP was reduced in male (13 ± 3 mmHg) and female SHR (18 ± 7 mmHg). Postexercise vasoconstrictor responses to PE were reduced in males due to an enhanced influence of nitric oxide. However, in females, postexercise vasoconstrictor responses to PE were not altered. Results suggest that nitric oxide- mediated α1-adrenergic receptor hyporesponsiveness contributes to PEH in male but not female SHR.
Age-related changes in urethrovesical coordination in male rats: relationship with bladder instability?
Authors: Lluel P. , Deplanne V. , Heudes D. , Bruneval P. , Palea S.
Published: March 2015

The micturition profile in conscious animals and the urethrovesical coordination in anesthetized conditions were investigated in 6- and 24-mo-old male Sprague-Dawley rats. The in vitro pharmacological responses to KCl, electrical field stimulation (EFS), carbachol, phenylephrine, and isoprenaline were determined in the isolated bladder body, the bladder neck, and urethra. A morphometric and immunohistological study has been included. During conscious cystomanometry, 63% of the aging rats but only 25% of the adult rats showed spontaneous contractions during the bladder-filling phase. In conscious aging rats, basal pressure, threshold pressure, and micturition pressure were also significantly increased. In anesthetized aging rats, a decrease in resting urethral pressure at micturition threshold and the occurrence of a significant delay in urethral relaxation during micturition were associated with an increased residual volume. In all isolated tissues, contractile response to KCl was not modified with aging, whereas age-related decreases in maximal responses to carbachol in the bladder body and to phenylephrine and carbachol in the urethra were observed. In the bladder neck only, we found a significant decrease in the amplitude of neurogenic contractions associated with fibrosis but without decrease in nerve density. These experiments show significant modifications in the voiding pattern of aging rats associated with urethral dysfunction and with regionally specific pharmacological and structural changes of the urinary tract. We propose that aging in rats is characterized by an impairment of the urethrovesical coordination, leading to bladder dysfunctions similar to those induced by bladder outlet obstruction.
Cholecystokinin selectively affects presympathetic vasomotor neurons and sympathetic vasomotor outflow
Authors: Sartor Daniela M. , Verberne Anthony J. M.
Published: March 2015

Cholecystokinin (CCK) is a potential mediator of gastrointestinal vasodilatation during digestion. To determine whether CCK influences sympathetic vasomotor function, we examined the effect of systemic CCK administration on mean arterial blood pressure (MAP), heart rate (HR), lumbar sympathetic nerve discharge (LSND), splanchnic sympathetic nerve discharge (SSND), and the discharge of presympathetic neurons of the rostral ventrolateral medulla (RVLM) in α-chloralose-anesthetized rats. CCK (1–8 μg/kg iv) reduced MAP, HR, and SSND and transiently increased LSND. Vagotomy abolished the effects of CCK on MAP and SSND as did the CCK-A receptor antagonist devazepide (0.5 mg/kg iv). The bradycardic effect of CCK was unaltered by vagotomy but abolished by devazepide. CCK increased superior mesenteric arterial conductance but did not alter iliac conductance. CCK inhibited a subpopulation (∼49%) of RVLM presympathetic neurons whereas ∼28% of neurons tested were activated by CCK. The effects of CCK on RVLM neuronal discharge were blocked by devazepide. RVLM neurons inhibited by exogenous CCK acting via CCK-A receptors on vagal afferents may control sympathetic vasomotor outflow to the gastrointestinal tract vasculature.
Angiotensin potentiates excitatory sensory synaptic transmission to medial solitary tract nucleus neurons
Authors: Barnes Karen L. , DeWeese Dannette M. , Andresen Michael C.
Published: March 2015

Femtomole doses of angiotensin (ANG) II microinjected into nucleus tractus solitarii (nTS) decrease blood pressure and heart rate, mimicking activation of the baroreflex, whereas higher doses depress this reflex. ANG II might generate cardioinhibitory responses by augmenting cardiovascular afferent synaptic transmission onto nTS neurons. Intracellular recordings were obtained from 99 dorsal medial nTS region neurons in rat medulla horizontal slices to investigate whether ANG II modulated short-latency excitatory postsynaptic potentials (EPSPs) evoked by solitary tract (TS) stimulation. ANG II (200 fmol) increased TS-evoked EPSP amplitudes 20–200% with minimal membrane depolarization in 12 neurons excited by ANG II and glutamate, but not substance P ( group A). Blockade of non- N-methyl-d-aspartate receptors eliminated TS-evoked EPSPs and responses to ANG II. ANG II did not alter TS-evoked EPSPs in 14 other neurons depolarized substantially by ANG II and substance P ( group B). ANG II appeared to selectively augment presynaptic sensory transmission in one class of nTS neurons but had only postsynaptic effects on another group of cells. Thus ANG II is likely to modulate cardiovascular function by more than one nTS neuronal pathway.
C/EBP DNA-binding activity is upregulated by a glucocorticoid-dependent mechanism in septic muscle
Authors: Penner Gail , Gang Gyu , Sun Xiaoyan , Wray Curtis , Hasselgren Per-Olof
Published: March 2015

Sepsis-induced muscle cachexia is associated with increased expression of several genes in the ubiquitin-proteasome proteolytic pathway, but little is known about the activation of transcription factors in skeletal muscle during sepsis. We tested the hypothesis that sepsis upregulates the expression and activity of the transcription factors CCAAT/enhancer binding protein (C/EBP)-β and -δ in skeletal muscle. Sepsis was induced in rats by cecal ligation and puncture, and control rats were sham operated. C/EBP-β and -δ DNA-binding activity was determined by electrophoretic mobility shift assay and supershift analysis. In addition, C/EBP-β and -δ nuclear protein levels were determined by Western blot analysis. Sepsis resulted in increased DNA-binding activity of C/EBP, and supershift analysis suggested that this reflected activation of the β- and δ-isoforms of C/EBP. Concomitantly, C/EBP-β and -δ protein levels were increased in the nuclear fraction of skeletal muscle. In additional experiments, we tested the role of glucocorticoids in sepsis-induced activation of C/EBP-β and -δ by treating rats with the glucocorticoid receptor antagonist RU-38486. This treatment inhibited the sepsis-induced activation of C/EBP-β and -δ, suggesting that glucocorticoids participate in the upregulation of C/EBP in skeletal muscle during sepsis. The present results suggest that C/EBP-β and -δ are activated in skeletal muscle during sepsis and that this response is, at least in part, regulated by glucocorticoids.
Molecular cloning and characterization of ryanodine receptor from unfertilized sea urchin eggs
Authors: Shiwa Mieko , Murayama Takashi , Ogawa Yasuo
Published: March 2015

Unfertilized eggs of sea urchins ( Hemicentrotus pulcherrimus) demonstrated cyclic ADP-ribose (cADPR)-induced Ca2+release and caffeine-induced Ca2+release, both of which were considered to be mediated through the ryanodine receptor (RyR). We cloned cDNAs for sea urchin egg RyR (suRyR), which encode a 597-kDa protein of 5,317 amino acids. suRyR shares common structural features with known RyRs: the well-conserved COOH-terminal domain, which forms a functional Ca2+channel, and a large hydrophilic NH2-terminal domain. suRyR shows amino acid sequence identity (43–45%) similar to the three mammalian RyR isoforms. Phylogenetic analysis indicates that suRyR branched from three isoforms of vertebrates before they diverged, suggesting that suRyR may be the only RyR isoform in the sea urchin. Four in-frame insertions were found in suRyR cDNAs, one of which was novel and unique, in that it had a cluster of serine residues. The transcripts with and without these insertions were found in the egg RNA. These results suggest that suRyR may be expressed as a functional Ca2+-induced Ca2+release channel, which might also be involved in cADPR-induced Ca2+release.
Cytokine-mediated downregulation of vasopressin V1Areceptors during acute endotoxemia in rats
Authors: Bucher Michael , Hobbhahn Jonny , Taeger Kai , Kurtz Armin
Published: March 2015

The reduced pressure response to vasopressin during acute sepsis has directed our interest to the regulation of vasopressin V1Areceptors. Rats were injected with lipopolysaccharide for induction of experimental gram-negative sepsis. V1Areceptor gene expression was downregulated in the liver, lung, kidney, and heart during endotoxemia. Inasmuch as the concentrations of proinflammatory cytokines such as interleukin-1β, tumor necrosis factor-α, and interferon-γ were highly increased during sepsis, the influence of these cytokines on V1Areceptor expression was investigated in primary cultures of hepatocytes and in the aortic vascular smooth muscle cell line A7r5. V1Areceptor expression was downregulated by the cytokines in a nitric oxide-independent manner. Blood pressure dose-response studies after injection of endotoxin showed a diminished responsiveness to the selective V1receptor agonist Phe2,Ile3,Orn8-vasopressin. Our data show that sepsis causes a downregulation of V1Areceptors and suggest that this effect is likely mediated by proinflammatory cytokines. We propose that this downregulation of V1Areceptors contributes to the attenuated responsiveness of blood pressure in response to vasopressin and, therefore, contributes to the circulatory failure in septic shock.
Brown fat and nonshivering thermogenesis in the gray mouse lemur (Microcebus murinus)
Authors: Génin F. , Nibbelink M. , Galand M. , Perret M. , Ambid L.
Published: March 2015

The gray mouse lemur Microcebus murinus is a rare example of a primate exhibiting daily torpor. In captive animals, we examined the metabolic rate during arousal from torpor and showed that this process involved nonshivering thermogenesis (NST). Under thermoneutrality (28°C), warming-up from daily torpor (body temperature <33°C) involved a rapid (<5 min) increase of O2consumption that was proportional to the depth of torpor ( n = 8). The injection of a β-adrenergic agonist (isoproterenol) known to elicit NST induced a dose-dependent increase in metabolic rate ( n = 8). Moreover, maximum thermogenesis was increased by cold exposure. For the first time in this species, anatomic and histological examination using an antibody against uncoupling protein (UCP) specifically demonstrated the presence of brown fat. With the use of Western blotting with the same antibody, we showed a likely increase in UCP expression after cold exposure, suggesting that NST is also used to survive low ambient temperatures in this tropical species.
Baroreflex stabilization of the double (pressure-rate) product at 0.05 Hz in conscious rabbits
Authors: Van Vliet Bruce N. , Belforti Francesca , Montani Jean-Pierre
Published: March 2015

The product of heart rate (HR) and systolic blood pressure (SBP), the double product (DP), is an indirect index of cardiac oxygen consumption. We used spectral analysis to test the hypothesis that baroreflex adjustments of HR stabilize the DP during spontaneous variations in SBP. SBP and HR were recorded by telemetry in five male conscious rabbits. HR and SBP power spectra each exhibited a low frequency peak at ∼0.05 Hz that was associated with high (>0.5) spectral coherence and a positive phase relationship between SBP and HR (SBP leading). A prominent peak was absent in the spectra of their product, suggesting that SBP and HR interacted to reduce DP variability in this frequency region. In contrast, a prominent 0.05-Hz peak was present in the power spectrum of calculated surrogates of the DP in which reflex interactions between HR and SBP had been removed. Our results suggest that baroreflex adjustments of HR stabilize the DP during spontaneous low-frequency variations in SBP in conscious rabbits.
The embryo makes red blood cell progenitors in every tissue simultaneously with blood vessel morphogenesis
Authors: Sequeira Lopez Maria Luisa S. , Cherñavvsky Daniel R. , Nomasa Takayo , Wall Lee , Yanagisawa Masashi , Gomez R. Ariel
Published: March 2015

During embryonic life, hematopoiesis occurs first in the yolk sac, followed by the aorto-gonado-mesonephric region, the fetal liver, and the bone marrow. The possibility of hematopoiesis in other embryonic sites has been suspected for a long time. With the use of different methodologies (transgenic mice, electron microscopy, laser capture microdissection, organ culture, and cross-transplant experiments), we show that multiple regions within the embryo are capable of forming blood before and during organogenesis. This widespread phenomenon occurs by hemo-vasculogenesis, the formation of blood vessels accompanied by the simultaneous generation of red blood cells. Erythroblasts develop within aggregates of endothelial cell precursors. When the lumen forms, the erythroblasts “bud” from endothelial cells into the forming vessel. The extensive hematopoietic capacity found in the embryo helps explain why, under pathological circumstances such as severe anemia, extramedullary hematopoiesis can occur in any adult tissue. Understanding the intrinsic ability of tissues to manufacture their own blood cells and vessels has the potential to advance the fields of organogenesis, regeneration, and tissue engineering.
Id2 expression during apoptosis and satellite cell activation in unloaded and loaded quail skeletal muscles
Authors: Alway Stephen E. , Martyn Julie K. , Ouyang Jun , Chaudhrai Archana , Murlasits Zsolt S.
Published: March 2015

Inhibitor of differentiation-2 (Id2) is a basic helix-loop-helix protein that acts as a negative regulator of the myogenic regulatory transcription factor family, but Id2 has also been implicated in apoptosis in several cell lines. In this study, we tested the hypothesis that Id2 has a role in both apoptosis-associated muscle atrophy and muscle hypertrophy. A weight corresponding to 12% of the body weight was attached to one wing of Japanese quail to induce hypertrophy in the patagialis (PAT) muscle. Birds in group 1 were killed after 5 ( n = 8), 7 ( n = 10), or 14 days ( n = 10) of loading. The left wing was loaded for 14 days in group 2 birds, and then the weight was removed and the PAT was examined after 7 ( n = 10), 14 ( n = 10), or 21 ( n = 5) days of unloading. A time-released bromodeoxyuridine (BrdU) pellet was implanted subcutaneously with wing weighting to identify activated satellite cells during loading. The left wing was loaded for 14 days, unloaded for 14 days, and then the weight was reattached for a subsequent 7 ( n = 10) or 14 days ( n = 10) in group 3 birds. BrdU was implanted on the second loading phase in this group. Id2 mRNA as measured by kinetic PCR increased by 3.9-, 2.7-, and 1.6-fold, relative to control levels after 7, 14, and 21 days of unloading ( group 2). Id2 protein as estimated by Western blots increased by 1.5-, 1.4-, and 0.75-fold after 7, 14, and 21 days of unloading ( group 2). Muscle unloading induced apoptosis, because poly(ADP-ribose) polymerase-(PARP)-positive nuclei increased and caspase 8 levels increased by 2.6- and 1.7-fold after 7 or 14 days of unloading, respectively ( group 2). Although BrdU-positive nuclei increased during loading ( groups 1 and 3), 50% failed to survive during unloading ( group 2). Id2 mRNA increased by 2.2- and 1.8-fold after 5 and 7 days of loading, respectively, but decreased to control levels by 14 days of loading in group 1. Id2 protein levels increased 2.1-fold after 5 days of loading ( group 1). In contrast, Id2 did not increase in reloaded muscles of group 3 birds. These data suggest that Id2 may have a role in apoptosis-associated atrophy of skeletal muscles, but its role in muscle hypertrophy is less clear.
Effect of peptide histidine isoleucine on consummatory behavior in rats
Authors: Olszewski Pawel K. , Wirth Michelle M. , Shaw Timothy J. , Grace Martha K. , Levine Allen S.
Published: March 2015

Peptide histidine isoleucine (PHI) and VIP are derived from the same precursor. While central VIP decreases food intake, potential effects of PHI on feeding have not been studied. In the current study, we found that PHI administered intracerebroventricularly (ICV) or into the hypothalamic paraventricular nucleus (PVN) or central nucleus of the amygdala (CeA) decreased food consumption in overnight-deprived rats. The magnitude of an anorexigenic response to PHI differed depending on the injection route: ICV-infused peptide evoked the most potent effect. We determined that that only PVN- and CeA-injected PHI did not have aversive consequences. In addition, we infused anorexigenic doses of PHI via the same routes and assessed Fos immunoreactivity of PVN oxytocin (OT) and vasopressin (VP) neurons using double immunohistochemistry. OT and VP are thought to promote feeding termination. PHI increased the percentage of Fos-positive OT neurons regardless of the injection route. PVN- and ICV-infused PHI induced activation of VP cells. We conclude that central PHI has an inhibitory influence on food intake in rats. The PVN, with OT and VP neurons, and CeA may be involved in the mediation of anorexigenic effects of PHI.
Pharyngeal branch of the glossopharyngeal nerve plays a major role in reflex swallowing from the pharynx
Authors: Kitagawa Jun-Ichi , Shingai Tomio , Takahashi Yoshihiro , Yamada Yoshiaki
Published: March 2015

Mechanical stimulation of the pharyngeal areas readily elicits reflex swallowing. However, it is much more difficult for electrical stimulation of the glossopharyngeal nerve (GPN) to evoke reflex swallowing than it is for stimulation of the superior laryngeal nerve (SLN) to do so. These paradoxical findings remain unexplained; hence, the main purpose of this study was to explain this contradiction by using a urethane-anesthetized rat. Mechanical stimulation easily elicited reflex swallowing from the pharynx. The posterior pillars, posterior pharyngeal wall, and the soft palate of the rat were extremely reflexogenic areas for swallowing. Sectioning the pharyngeal branch of the GPN (GPN-ph), however, eliminated the swallowing reflex from these areas. In contrast, sectioning the lingual branch of the GPN had no effect on the elicitation of swallowing. Electrical stimulation of the GPN-ph and SLN elicited sequentially occurring swallows. The relationship between stimulus frequency and the latency of swallowing for the GPN-ph was approximately the same as that for the SLN. These results indicate that the GPN-ph plays a major role in the initiation of reflex swallowing from the pharynx in rats.
Ascorbate inhibits iNOS expression and preserves vasoconstrictor responsiveness in skeletal muscle of septic mice
Authors: Wu Feng , Wilson John X. , Tyml Karel
Published: March 2015

Inducible nitric oxide synthase (iNOS) expression in blood vessels contributes to the vascular hyporeactivity characteristic of sepsis. Our previous work demonstrated in vitro that ascorbate inhibits iNOS expression in lipopolysaccharide- and interferon-γ-stimulated skeletal muscle endothelial cells (ECs) through an antioxidant mechanism. The present study evaluated in vivo the hypothesis that administration of ascorbate decreases oxidative stress, prevents endothelial iNOS expression, and improves vascular reactivity in septic skeletal muscle. Sepsis was induced in C57BL/6 mice by cecal ligation and puncture (CLP). Plasma nitrite and nitrate (NOx) levels were elevated by 6 h after CLP. Prior ascorbate bolus injection (200 mg/kg body wt iv) blocked the elevation of plasma NOx and abolished the expression of iNOS protein and activity in the septic skeletal muscle. We also demonstrated that iNOS mRNA determined by RT-PCR was induced in the microvascular ECs of the muscle at 3 h after CLP. This induction was attenuated by prior ascorbate administration. Ascorbate inhibition of iNOS expression was associated with decreased oxidant levels in the septic muscle. Moreover, ascorbate administration restored partially the baseline arterial pressure and preserved completely the microvascular constriction and arterial pressure responses to norepinephrine in CLP mice. These results suggest that early administration of ascorbate may be a valuable adjunct treatment of sepsis.
Genomics and homeostasis
Authors: Cowley Allen W.
Published: March 2015

The Cannon lecture this year illustrates how knowledge of DNA sequences of complex living organisms is beginning to shape the landscape of physiology in the 21st century. Enormous challenges and opportunities now exist for physiologists to relate the galaxy of genes to normal and pathological functions. The first extensive genomic systems biology map for cardiovascular and renal function was completed last year as well as a new hypothesis-generating tool (“physiological profiling”) that enables us to hypothesize relationships between specific genes responsible for the regulation of regulatory pathways. Techniques of chromosomal substitution (consomic and congenic rats) are beginning to confirm statistical results from linkage analysis studies, narrow the regions of genetic interest for positional cloning, and provide genetically well-defined control strains for physiological studies. Patterns of gene expression identified by microarray and mapping of expressed genes to chromosomal sites are adding to the understanding of systems physiology. The previously unimaginable goal of connecting ∼36,000 genes to the complex functions of mammalian systems is indeed well underway.
Influence of vestibular activation on respiration in humans
Authors: Monahan Kevin D. , Sharpe Melissa K. , Drury Daniel , Ertl Andrew C. , Ray Chester A.
Published: March 2015

The purpose of this study was to determine the effects of the semicircular canals and otolith organs on respiration in humans. On the basis of animal studies, we hypothesized that vestibular activation would elicit a vestibulorespiratory reflex. To test this hypothesis, respiratory measures, arterial blood pressure, and heart rate were measured during engagement of semicircular canals and/or otolith organs. Dynamic upright pitch and roll (15 cycles/min), which activate the otolith organs and semicircular canals, increased respiratory rate (Δ2 ± 1 and Δ3 ± 1 breaths/min, respectively; P < 0.05). Dynamic yaw and lateral pitch (15 cycles/min), which activate the semicircular canals, increased respiration similarly (Δ3 ± 1 and Δ2 ± 1, respectively; P < 0.05). Dynamic chair rotation (15 cycles/min), which mimics dynamic yaw but eliminates neck muscle afferent, increased respiration (Δ3 ± 1; P < 0.05) comparable to dynamic yaw (15 cycles/min). Increases in respiratory rate were graded as greater responses occurred during upright (Δ5 ± 2 breaths/min) and lateral pitch (Δ4 ± 1) and roll (Δ5 ± 1) performed at 30 cycles/min. Increases in breathing frequency resulted in increases in minute ventilation during most interventions. Static head-down rotation, which activates otolith organs, did not alter respiratory rate (Δ1 ± 1 breaths/min). Collectively, these data indicate that semicircular canals, but not otolith organs or neck muscle afferents, mediate increased ventilation in humans and support the concept that vestibular activation alters respiration in humans.
Hypotensive effect of ANG II and ANG-(1–7) at the caudal ventrolateral medulla involves different mechanisms
Authors: Alzamora A. C. , Santos R. A. S. , Campagnole-Santos M. J.
Published: March 2015

The objective of the present study was to determine the contribution of the autonomic nervous system and nitric oxide to the depressor effect produced by unilateral microinjection of ANG-(1–7) and ANG II into the caudal ventrolateral medulla (CVLM). Unilateral microinjection of ANG-(1–7), ANG II (40 pmol), or saline (100 nl) was made into the CVLM of male Wistar rats anesthetized with urethane before and after intravenous injection of 1) methyl-atropine, 2.5 mg/kg; 2) prazosin, 25 μg/kg; 3) the nitric oxide synthase (NOS) inhibitor, N G-nitro-l-arginine methyl ester (l-NAME), 5 mg/kg; or 4) the specific inhibitor of neuronal NOS, 7-nitroindazole (7-NI), 45 mg/kg. Arterial pressure and heart rate (HR) were continuously monitored. Microinjection of ANG-(1–7) or ANG II into the CVLM produced a significant decrease in mean arterial pressure (MAP; −11 ± 1 mmHg, n = 12 and −10 ± 1 mmHg, n= 10, respectively) that was not accompanied by consistent changes in HR or in cardiac output. The effect of ANG-(1–7) was abolished after treatment with methyl-atropine (−3 ± 0.6 mmHg, n = 9) or l-NAME (−2.3 ± 0.5 mmHg, n = 8) or 7-NI (−2.8 ± 0.6 mmHg, n = 5). In contrast, these treatments did not significantly interfere with the ANG II effect (−10 ± 2.6 mmHg, n = 8; −8 ± 1.5 mmHg, n = 8; and −12 ± 3.6 mmHg, n = 6; respectively). Peripheral treatment with prazosin abolished the hypotensive effect of ANG-(1–7) and ANG II. Microinjection of saline did not produce any significant change in MAP or in HR. These results suggest that the hypotensive effect produced by ANG II at the CVLM depends on changes in adrenergic vascular tonus and, more importantly, the hypotensive effect produced by ANG-(1–7) also involves a nitric oxide-related mechanism.
Two nitridergic peptides are encoded by the genecapabilityinDrosophila melanogaster
Authors: Kean Laura , Cazenave William , Costes Laurence , Broderick Kate E. , Graham Shirley , Pollock Valerie P. , Davies Shireen A. , Veenstra Jan A. , Dow Julian A. T.
Published: March 2015

A Drosophila gene ( capability, capa) at 99D on chromosome 3R potentially encodes three neuropeptides: GANMGLYAFPRV-amide (capa-1), ASGLVAFPRV-amide (capa-2), and TGPSASSGLWGPRL-amide (capa-3). Capa-1 and capa-2 are related to the lepidopteran hormone cardioacceleratory peptide 2b, while capa-3 is a novel member of the pheromone biosynthesis-activating neuropeptide/diapause hormone/pyrokinin family. By immunocytochemistry, we identified four pairs of neuroendocrine cells likely to release the capa peptides into the hemolymph: one pair in the subesophageal ganglion and the other three in the abdominal neuromeres. In the Malpighian (renal) tubule, capa-1 and capa-2 increase fluid secretion rates, stimulate nitric oxide production, and elevate intracellular Ca2+and cGMP in principal cells. Capa-stimulated fluid secretion, but not intracellular Ca2+concentration rise, is inhibited by the guanylate cyclase inhibitor methylene blue. The actions of capa-1 and capa-2 are not synergistic, implying that both act on the same pathways in tubules. The capa gene is thus the first to be shown to encode neuropeptides that act on renal fluid production through nitric oxide.
The zebrafish: a new model organism for integrative physiology
Authors: Briggs Josephine P.
Published: March 2015

This brief review summarizes features of the zebrafish, Danio rerio, that make it a suitable model organism for studies of regulatory physiology. The review presents the argument that random mutagenesis screens are a valuable gene-finding strategy to identify genes of functional importance and that their utility, although well established for developmental issues, will extend to a variety of topics of interest to the regulatory physiologist. Particular attention is drawn to the range of functional responses amenable to mutagenesis screens in larval zebrafish. Other virtues of the organism, the range of genomic tools, the potential for innovative optical methods, and the tractability for genetic and other experimental manipulations, are also described. Finally, the review provides examples of functional studies in zebrafish, including studies in sensory neurons, cardiac rhythm disturbances, gastrointestinal function, and studies of the developing kidney, that illustrate potential applications. Because of the relative ease with which combinatorial studies can be performed, the zebrafish may eventually be particularly valuable in understanding the functional interaction between subtle gene defects that cause polygenic disorders.