bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sodium‐induced allosteric changes in D2 dopamine receptor local dynamics modulate ligand selectivity
Authors: Schetz John A. , Ericksen Spencer S. , Cummings David F. , Weinstein Harel 
Published: June 2021

The basis of allostery in GPCRs and its implications for ligand recognition remain a mystery. While determining the source of large differences in measured ligand affinity reported for a mutant D2 dopamine receptor, we uncovered a unique and significant allosteric response to the physiological modulator sodium. This response is characterized by a sodium‐dependent enhanced affinity for ligands of a specific structural class having either agonist or antagonist functional properties. To explore possible mechanisms for our empirically‐derived results, the influence of sodium on D2 receptor dynamics was examined by computational analysis of the molecular normal modes of motion. This result revealed divergence in the component motions of the D2 receptor with and without sodium bound to the putative sodium binding regions. One particularly sensitive mode involved the concerted motions of the extracellular portions of transmembrane‐spanning domains, which when computed in the presence of sodium appeared to disrupt a favorable pi‐stacking interaction between TM2 and TM3 freeing an aromatic residue in the receptor model for favorable interactions with aromatic portions of the ligands increasing their affinity. This demonstrates how a sodium‐dependent change in dynamic properties can yield the experimentally observed allosteric phenomenon.Supported R01 MH063162 (JAS), P01 DA012923 and K05 DA00060 (HW).
AP‐1 is activated by relaxin family peptides in cells expressing the relaxin family peptide receptor 3 (RXFP3)
Authors: van der Westhuizen Emma T , Sexton Patrick M , Summers Roger J 
Published: June 2021

Relaxin‐3 is a neuropeptide involved in appetite regulation and stress behaviour in rats. RXFP3 is the cognate receptor for relaxin‐3 that is coupled to cAMP inhibition and ERK1/2 activation in CHO‐K1 and HEK293 cell lines recombinantly expressing the receptor. Competition for [125I]‐INSL5/H3 relaxin chimera binding is observed with H3 relaxin and the B‐chain of H3 relaxin, but not with any other relaxin family peptides. We identified that H3 relaxin but also H2 relaxin and porcine relaxin activate transcription from AP‐1 elements in CHO and HEK cells transiently expressing human RXFP3 receptors, measured using a reporter gene. H2 relaxin was more potent at activating transcription than either H3 relaxin or porcine relaxin. Experiments with inhibitors of p38 MAPK (RWJ67657, 10 μM), MEK1/2 (PD98059, 20μM) and JNK (SP600125, 10μ M) showed that AP‐1 activation involved p38 MAPK in CHO‐K1 cells stimulated with H3 relaxin, H2 relaxin or porcine relaxin. In HEK293 cells, AP‐1 activation in response to H3 relaxin or porcine relaxin involved p38 MAPK, MEK1/2 and JNK, but, when stimulated with H2 relaxin, it involved only a MEK1/2 pathway. We propose that different relaxin family peptides interact at different sites on RXFP3, to activate distinct signalling pathways.This research was supported by National Health and Medical Research Council Project Grants 436713 and 454375
Ischemia‐induced Stimulation of the BBB Na‐K‐Cl Cotransporter: Evidence for a Role of p38 MAP Kinase
Authors: Wallace Breanna K , Jelks Karen A , Foroutan Shahin , O’Donnell Martha E 
Published: June 2021

Increased blood‐brain barrier (BBB) Na‐K‐Cl cotransporter activity appears to contribute to cerebral edema formation during ischemic stroke. The cotransporter is stimulated by hypoxia and aglycemia, although the mechanisms responsible are unknown. Inhibition of p38MAP kinase (p38MAPK), which is activated by ischemia, has been found to reduce brain infarct in ischemic stroke. In the present study we examined the possibility that p38MAPK participates in ischemia‐induced stimulation of the BBB Na‐K‐Cl cotransporter. Cerebral microvascular endothelial cells (CMEC) were exposed to hypoxia (7.5% O2) or to aglycemia, then subjected to Western blot analysis, using antibodies that recognize phosphorylated (activated) p38MAPK (p‐p38MAPK) or both phosphorylated and non‐phosphorylated (total) p38MAPK. CMEC were also evaluated for cotransporter activity as bumetanide‐sensitive K influx. Hypoxia (5 – 120 min) and aglycemia (30 min) caused 1.9‐ and 2.8‐fold increases in p‐p38MAPK levels without changing total p38MAPK. Exposing CMEC to the p38 MAPK inhibitor SB239063 (20 μM) abolished hypoxia‐ and aglycemia‐induced increases in Na‐K‐Cl cotransporter activity. Confocal immunofluorescence of perfusion‐fixed rat brain slices also revealed the presence of p38MAPK in BBB in situ. These findings suggest that p38 MAPK participates in ischemia stimulation of BBB Na‐K‐Cl cotransporter activity.Supported by NINDS
Integrative mechanisms of blood pressure regulation in humans and rats: cross‐species similarities
Authors: Charkoudian Nisha , Gusman Elle , Joyner Michael J. , Wallin Gunnar , Osborn John 
Published: June 2021

Inter‐individual variability in hemodynamic variables appears to be important in human blood pressure regulation. It is not known whether the rat, often used for studies of cardiovascular regulation, exhibits similar inter‐individual variability. In the present study, we evaluated whether inter‐individual variability in cardiac output (CO) and total peripheral resistance (TPR) is similar in humans and in rats, and whether a balance between these variables is similar in the two species. We assessed the relationship between CO and TPR during control conditions in humans (N = 40) and in Sprague‐Dawley rats (N = 16). We further assessed whether the relationship between CO and TPR was altered during acute increases in blood pressure, which were accomplished in humans with acute systemic L‐NMMA (N = 17), and in rats with a DOCA‐salt model (N = 16). Both humans and rats showed marked inter‐individual variability in CO and TPR but low variability in blood pressure. In both species, CO and TPR showed strong inverse correlations during normotension (r2 = 0.88 (humans) and 0.89 (rats)) and during blood pressure increases (r2 = 0.91 (humans) and 0.58 (rats)). We conclude that inter‐individual variability CO and TPR, and the balance between these variables, are important aspects of blood pressure regulation in both humans and rats.Supported by NIH HL32352, HL83947, HL64176, UL1‐RR24150 and Swedish Research Council 12170.
Central but not peripheral G‐alpha i/o protein inhibition potentiates hypertension in hypertensive Dahl salt‐sensitive rats: a protective role for central G‐alpha i/o proteins
Authors: Wainford Richard David , Kapusta Daniel R 
Published: June 2021

We have shown that intracerebroventricular (i.c.v.) pre‐treatment of rats with pertussis toxin (PTX) prevents the hypotensive and bradycardic responses to the Gαi/o‐protein coupled receptor ligands, nociceptin/orphanin FQ and clonidine. These studies examined whether central Gαi/o protein inhibition alters blood pressure in hypertensive Dahl salt sensitive (DSS) rats.Methods DSS rats were implanted with radio‐telemetry probes and MAP and HR were continuously monitored. After 1‐week, rats were maintained on 8% NaCl chow for 3 weeks then administered either i.c.v. iso‐saline vehicle (N=6), i.c.v. PTX (1 μg) (N=6), or intraperitoneal (i.p.) PTX (15 μg/kg) (N=6).Results DSS rats on 8% NaCl chow showed a significant increase in MAP (normal chow MAP, 130 ± 2 mmHg; 8% NaCl chow, 164 ± 8 mmHg, P<0.05). In hypertensive DSS rats, central PTX significantly increased MAP (day 4 post i.c.v. PTX; MAP Δ +25 ± 2 mmHg, P<0.05). In contrast, peripheral PTX administration produced a significant hypotension (day 4 post i.p. PTX; MAP Δ −58 ± 9 mmHg, P<0.05).Conclusion In hypertensive DSS rats, endogenous central Gαi/o protein pathways participate in reducing the severity of high NaCl‐induced hypertension. This is in contrast to the role of peripheral Gαi/o proteins, which in these (DSS) and previous studies (spontaneously hypertensive rats) play a pathological role in the maintenance of hypertension. Thus, endogenous central vs. peripheral Gαi/o proteins have differential affects on blood pressure control and potentially in the etiology of hypertension. DK43337, HL 071212, P20 RR018766
Human muscle sympathetic action potential patterns during graded lower body negative pressure
Authors: Liu Yinchun , Shoemaker J. Kevin 
Published: June 2021

This study assessed baroreflex modulation of within‐burst neural action potential (spike) discharge in muscle sympathetic nerve activity (MSNA). Spike rate and inter‐spike interval were exposed from raw MSNA recorded from 6 healthy individuals during graded lower body negative pressure (LBNP) (baseline, −10, −40, −60 mmHg). The first 30s raw MSNA of the 4th min for each LBNP level was analyzed after applying a spike detection method (Autonomic neuroscience: Basic & Clinical 143(2007) 92–105). Spikes/30 sec increased progressively with LBNP beginning at −10 mmHg (P<0.05), with a doubling of spike rate (range = 40 – 290%) at −60 mmHg. Mean inter‐spike interval decreased progressively from 0.175±0.045 s at Baseline to 0.087±0.028 s at −60 LBNP (P<0.05) reflecting increases in average discharge frequencies from 5 to 10 Hz. In probability distributions, progressive increases in the proportion of spikes occurred only within the shortest inter‐spike interval bin (ranging 0.04 (25 Hz) – 0.1 (10 Hz) s across participants). Thus, the increment in MSNA with baroreceptor unloading is focused at high‐frequency discharge patterns and reflects progressive increments in action potential content with evidence for a doubling of neurons recruited between baseline and high levels of orthostatic stress.Supported by NSERC‐CHRP
Glucosamine Inhibits TNF‐α‐Induced Expression of Inflammatory Mediators In Rat Aortic Smooth Muscle Cells through Inhibition of NFκB Activation
Authors: XING DONGQI , Feng Wenguang , Chen Yiu‐Fai , Chatham John C , Oparil Suzanne 
Published: June 2021

Objective:This study tested whether glucosamine (GlcN), an amino suger that increases O‐GlcNAc modification of proteins by increasing flux through the hexosamine biosynthesis pathway, can protect vascular smooth muscle cells (SMCs) against inflammatory stress.Methods and Results:Quiescent cultured rat aortic SMCs (RASMCs) were pretreated with GlcN (5 mM) or vehicle for 1 hr and then stimulated with tumor necrosis factor (TNF)‐α (10 ng/ml) for another 15 min or 6 hrs. Total and phosphorylated IκBα were measured by western blot analysis. NFκB DNA binding activity were determined by ELISA. RNA was extracted for real‐time RT‐PCR analysis of chemokine and adhesion molecule expression. Nucleocytoplasmic protein subjected to western blot analysis of global O‐GlcNAcylated protein using the selective CTD110.6 antibody. GlcN treatment enhanced overall O‐GlcNAcylated protein levels and inhibited chemokine and adhesion molecule expression, IκBα phosphorylation, prevented the degradation of IκBα and inhibited NFκB activation in TNF‐α‐stimulated RASMCs.Conclusions:O‐GlcNAc modification may protect the vasculature from inflammatory stresses.This work was supported, in part, by American Heart Association Greater Southeast Affiliate grant 0425455B, 0765398B.
Mechanism of vasodilatation with N‐acetylcysteine and NaHS: Contribution of ATP‐sensitive potassium channels
Authors: Yamamoto Michiko , Adachi Takeshi , Ishiwata Kyoko , Ikeda Satsuki , Hirayama Yoshiaki , Soga Tomoyoshi , Suematsu Makoto 
Published: June 2021

Objective: Hydrogen sulfide (H2S) is known as a toxic gas, however, recent studies reveal H2S as the third gaseous vasodilator, following nitric oxide and carbon monoxide. N‐acetylcysteine (NAC) is often used as an anti‐oxidant and it can increase intracellular cysteine (Cys) levels to produce H2S. In this study we tested the contribution of ATP‐sensitive potassium channels (IKATP) to NAC‐ and NaHS‐induced relaxation and the metabolic changes induced by H2S.Methods: Vascular function was assessed with isometric tension measurement of aortic rings equipped in the organ bath. After aortic constriction with phenyrephrin, a dose‐dependent relaxations to NAC/NaHS (0.3–10 mM) were measured. Some rings were pre‐treated with L‐NAME (100 μM), ODQ (10 μM), or glybenclamide (GLB: 10 μM), an IKATP blocker. Aortic homogenates were prepared and vascular metabolome analysis was performed with capillary electrophoresis/mass spectrometry. Results: Neither L‐NAME nor ODQ affected the aortic relaxations to NAC/NaHS. GLB decreased the maximum relaxation to NaHS. Notably, GLB decreased the speed of relaxation to NAC/NaHS in the early phase. NaHS increased the vascular AMP levels about five folds (31.4±5.8 vs 158.5±31.6 nM).Conclusion: Aortic relaxations to NAC/NaHS are involved with hyperpolarization via the activation of IKATP. An increase in intracellular AMP levels by H2S, activates IKATP to modulate vascular tone.
Changes in GDNF protein content of skeletal muscle following involuntary exercise are long lived
Authors: Kinnell Kyle R. , Czarnopys Monica J. , Spitsbergen John M. 
Published: June 2021

Glial‐cell line derived neurotrophic factor (GDNF) is a neurotrophic factor produced by skeletal muscle. GDNF has been shown to be potent survival factor for motor neurons. We have previously shown that GDNF content in skeletal muscle is altered following exercise and GDNF levels 24 hours after the last bout of exercise are significantly different than those measured immediately after exercise. We sought to determine how long after exercise do GDNF protein levels remain altered. We removed extensor digitorum longus (EDL) and Soleus (SOL), 24 hr, 72 hr and 1 week following the last bout of involuntary exercise. Muscles were processed for GDNF protein content using enzyme linked immunosorbant assay. Contralateral EDL and SOL were removed at the same time points for immunohistochemical analysis. The results showed that 72 hr following exercise there was a significant increase of GDNF protein content in SOL and a significant decrease in EDL. The results suggest exercise causes a relatively long‐lived effect on GDNF protein content and that expression of GDNF protein in type I skeletal muscle maybe regulated differently that that in type II skeletal muscle.This work was supported by NIH Grant 1R15AG022908‐01A2, MSU‐KCMS, and Western Michigan University.
Contribution of intracellular structures into static and relaxation properties of papillary muscles
Authors: Smoluk Leonid , Kobelev Alexandr , Lookin Oleg , Balakin Alexandr , Protsenko Yuri 
Published: June 2021

Differentiating the role of extracellular matrix and intracellular structures of myocardium in the total mechanical response of passive muscles now takes attention of researchers due to recently investigated nonlinear features of giant intracellular protein titin. We assume here that the variety of spatial structures on a fascicule level can be represented by 2D‐model consisting of inclined, longitudinal and transversal elastic springs and damping elements. The titin block (consisting of N=10 times repeated rhombic structure) is inserted in the bulk of parallelogram‐shaped fascicule block. Now we can calculate steady state stress‐strain curve, hysteresis loop, and stress relaxation under step‐wise stretching in the model with or without titin block.It was found that intracellular structures are the main sources of non‐linearity of stress‐strain relation. We have superimposed stress‐strain relations obtained for papillary muscle in normal conditions and after application of NaOH which disrupted intracellular structures of the muscle (Fig. 1A). The experimental protocol we used is shown on Fig. 1B (normal conditions) and after treatment of NaOH solution (Fig. 1C).Studying the difference in normal case and after treating with NaOH, we can evaluate the partial contribution of intracellular structures into passive mechanics of papillary muscles.This work is supported by RFBR URALS Grant #04‐04‐961091.
The effect of progesteron on brain malondialdehyde and gluthatione levels in the experimental epilepsy in mice
Authors: Pence Sadrettin , Erkutlu Ibrahim , Alptekin Mehmet , Kurtul Naciye , Pence Halime Haným 
Published: June 2021

Objective:The aim of the present investigation was to determine the effects of progesterone on malondialdehyde and gluthatione levels in the different brain regions after PTZ‐induced epilepsy in the mice.Material and Methods:Total 80 mice have been separated into 8 groups consisting of 10 mice. The groups were the sham, control, PTZ, PTZ plus progesterone, five dose progesterone, single dose progesterone, kindling, and kindling plus progesterone groups. In all groups brains were divided into 5 parts as right hemisphere, left hemisphere, right brain stem, left brain stem and cerebellum under microscopy. Malondialdehyde and gluthatione levels were measured spectrophotometrically.Results:MDA levels of 3rd and 7th groups in all brain regions were significantly higher than those of the other groups (P<0.05). While highest values were found in brain stems, lowest values were in the cerebral hemispheres. Moderate elevation was seen in the cerebellum compared to the sham group. MDA levels of in all brain regions decreased markedly in the groups who were given progesterone treatment compared to the control group (P<0.05), but no statistically significant increase was found in all other groups. Gluthatione levels of the groups with progesterone were significantly higher than those of the other groups (P<0.05). In addition, Gluthatione levels ere significantly lower in both 3rd and 7th groups in all brain regions.Conclusion:We demonstrated that progesterone improves experimental epilepsy by decreasing MDA and increasing gluthatione levels in both the brain hemispheres and brainstem structures.
The effect of intentional cranial deformation on frontal sinus development and morphology
Authors: Tessema Belachew , Lawson William , Schaefer Steven D , Marquez Samuel 
Published: June 2021

Introduction: Intentional cranial deformation (ICD) has been documented to be a world‐wide phenomenon whose practice elicits considerable shape changes to the neurocranium during the early stages of postnatal development. Since the development of the frontal sinuses begins after early childhood, the application of ICD procedures should affect morphological growth trajectories in its anatomy. This qualitative and quantitative study examines the effects of ICD on the frontal sinus development and morphology.Methods: Twenty intentionally deformed (ID) and twenty non‐deformed (ND) dry crania from distinct Bolivian and Peruvian indigenous populations were selected from the Division of Anthropology at the American Museum of Natural History. The crania were scanned using a hispeed helical CT scanner. Craniofacial linear measures, along with endocranial (EC) and frontal sinus volumetric determinations were obtained using a three dimensional (3‐D) volume rendering program.Results: 3‐D reconstructed volumetric studies showed no statistical differences between the EC volume of ID and ND crania. Analysis of frontal angle showed statistically significant difference between ID and ND crania (p<0.001). Volumetric measurements of frontal sinus showed no statistically significant differences between ID and ND crania.Conclusion: ICD procedures affect more readily the extrasplanchnocranial moiety as detected by external linear measurements of adult crania. However, the development of the frontal sinus seems not to be affected by these external changes. This study emphasizes the developmental potential of the paranasal sinuses which is not affected by structural changes within the neurocranium.
Carpal bones and Tarsal bones in Korean Chinese water deer (Hydropotes inermis argyropus, Heude 1884)
Authors: Ahn Dongchoon 
Published: June 2021

Hydropotes inermis argyropus, Chinese water deer living in Korea, belongs to Order of Artiodactyla and Family of Cervidae. However, it was regarded as a primitive deer in its large laniary canine teeth and the absence of antlers. Carpal bone and tarsal bone are different in their number among animals even in Cervidae caused by absent or fusion between them. So, the shape and number of carpal bones and tarsal bones were used for the morphological feature in determining Cervidae affinities. We investigated the carpal bone and tarsal bones in skeletons in 11 H. inermis arygyropus. Their body weights were above 10 kg. 10 H. inermis arygyropus had 7 carpal bones that were consisted of radial carpal, intermediate carpal, ulnar carpal, and accessory carpal bone in proximal row, firs carpal bone, fused second and third carpal bones, and fourth carpal bone in distal row. This arrangement and articulation with antebrachium, metacarpal and each other was similar with other telemetacarpal type deer. 5 tarsal bones were shown in 10 animals. Calcaneus and talus consist of proximal row, the first tarsal, fused second and third tarsal bones, and fused centroquartal bone in distal row. The arrangement and number of tarsal bone are similar with other Cervidae except Pudu, Muntiacus, and Elaphodus. There is no sesamoid bone which was observed occasionally in small ruminants. One female had one more carpal bone and tarsal bone that might be considered as the fifth carpal bone and the fifth tarsal bone with regarding the location and references. These bones were so tiny with size of 2.0×1.5×1.0mm.These results suggest that H. inermis arygyropus could be a good deer to study on the limb skeleton in phylogenetic research.This study was supported by Korea Research Foundation
Grading system for osteophytic changes in zygapophysial (Z) joints following induced segmental hypomobility in the rat
Authors: Cramer Gregory D. , Henderson Charles N.R. , Pocius Judy D. , Little Joshua W. , Grieve Thomas J. , Daley Clover J. 
Published: June 2021

Osteophytic changes (OCs) have been identified on the cephalad articular processes (CAPs) of hypomobile zygapophysial (Z) joints of rats. Our objective was to refine the method of grading OCs for use in a large scale study. Thirty‐eight Z joint CAPs (left and right L4, L5, L6, and S1) of control and experimental rats were assessed. The experimental animals had undergone 8 weeks of fixation, using an established, IACUC approved, rat model, in which 3 contiguous segments (L4, L5, L6) were fixed with a specially engineered, surgically implanted, vertebral fixation device. The spines of all animals had been prepared for dissection microscopy. The CAPs were graded by 2 observers using specific OC criteria developed for this study. The lateral, cephalad, and dorsal surfaces of each CAP were systematically evaluated. Each observer graded the spines on 2 separate occasions, separated by 30 days. Intra‐ and inter‐observer reliability of grading was assessed using kappa coefficients. Results: Intra‐examiner reliability was 0.62. Inter‐examiner reliability was 0.64. We conclude that good reliability was achieved using these methods. Future studies will use a consensus procedure for segments scored differently by the two observers.Support: NIH/NCCAM (Grant #s 1R21 AT00784 and U19 AT002006).