Effects of Cold Adaptation on the Modulatory Action of TRH Upon Temperature Sensitive and Insensitive Hypothalamic Neurons of Rats

1994 ◽  
pp. 67-72 ◽  
Author(s):  
B. Tzschentke ◽  
J. Schenda ◽  
Fr.-K. Pierau
Keyword(s):  
Cold Adaptation ◽  
Temperature Sensitive ◽  
Hypothalamic Neurons

scholarly journals Evolution of nonspectral rhodopsin function at high altitudes

2017 ◽  
Vol 114 (28) ◽  
pp. 7385-7390 ◽  
Author(s):  
Gianni M. Castiglione ◽  
Frances E. Hauser ◽  
Brian S. Liao ◽  
Nathan K. Lujan ◽  
Alexander Van Nynatten ◽  
...  
Keyword(s):  
High Altitude ◽  
Cold Adaptation ◽  
Natural Variation ◽  
Thermal Adaptation ◽  
Intramolecular Hydrogen Bonding ◽  
Site Directed Mutagenesis ◽  
Temperature Sensitive ◽  
Cold Temperatures ◽  
Trade Offs ◽  
Intramolecular Hydrogen

High-altitude environments present a range of biochemical and physiological challenges for organisms through decreases in oxygen, pressure, and temperature relative to lowland habitats. Protein-level adaptations to hypoxic high-altitude conditions have been identified in multiple terrestrial endotherms; however, comparable adaptations in aquatic ectotherms, such as fishes, have not been as extensively characterized. In enzyme proteins, cold adaptation is attained through functional trade-offs between stability and activity, often mediated by substitutions outside the active site. Little is known whether signaling proteins [e.g., G protein-coupled receptors (GPCRs)] exhibit natural variation in response to cold temperatures. Rhodopsin (RH1), the temperature-sensitive visual pigment mediating dim-light vision, offers an opportunity to enhance our understanding of thermal adaptation in a model GPCR. Here, we investigate the evolution of rhodopsin function in an Andean mountain catfish system spanning a range of elevations. Using molecular evolutionary analyses and site-directed mutagenesis experiments, we provide evidence for cold adaptation in RH1. We find that unique amino acid substitutions occur at sites under positive selection in high-altitude catfishes, located at opposite ends of the RH1 intramolecular hydrogen-bonding network. Natural high-altitude variants introduced into these sites via mutagenesis have limited effects on spectral tuning, yet decrease the stability of dark-state and light-activated rhodopsin, accelerating the decay of ligand-bound forms. As found in cold-adapted enzymes, this phenotype likely compensates for a cold-induced decrease in kinetic rates—properties of rhodopsin that mediate rod sensitivity and visual performance. Our results support a role for natural variation in enhancing the performance of GPCRs in response to cold temperatures.

Cyclic GMP alters the firing rate and thermosensitivity of hypothalamic neurons

2008 ◽  
Vol 294 (5) ◽  
pp. R1704-R1715 ◽  
Author(s):  
Chadwick L. Wright ◽  
Penny W. Burgoon ◽  
Georgia A. Bishop ◽  
Jack A. Boulant
Keyword(s):  
Firing Rate ◽  
Cyclic Nucleotide ◽  
Temperature Sensitive ◽  
Tissue Slices ◽  
Hypothalamic Neurons ◽  
Ambient Temperatures ◽  
Thermoregulatory Responses ◽  
Gated Channel ◽  
Cgmp Analog ◽  
Rostral Hypothalamus

The rostral hypothalamus, especially the preoptic-anterior hypothalamus (POAH), contains temperature-sensitive and -insensitive neurons that form synaptic networks to control thermoregulatory responses. Previous studies suggest that the cyclic nucleotide cGMP is an important mediator in this neuronal network, since hypothalamic microinjections of cGMP analogs produce hypothermia in several species. In the present study, immunohistochemisty showed that rostral hypothalamic neurons contain cGMP, guanylate cyclase (necessary for cGMP synthesis), and CNG A2 (an important cyclic nucleotide-gated channel). Extracellular electrophysiological activity was recorded from different types of neurons in rat hypothalamic tissue slices. Each recorded neuron was classified according to its thermosensitivity as well as its firing rate response to 2–100 μM 8-bromo-cGMP (a membrane-permeable cGMP analog). cGMP has specific effects on different neurons in the rostral hypothalamus. In the POAH, the cGMP analog decreased the spontaneous firing rate in 45% of temperature-sensitive and -insensitive neurons, an effect that is likely due to cGMP-enhanced hyperpolarizing K+ currents. This decreased POAH activity could attenuate thermoregulatory responses and produce hypothermia during exposures to cool or neutral ambient temperatures. Although 8-bromo-cGMP did not affect the thermosensitivity of most POAH neurons, it did increase the warm sensitivity of neurons in other hypothalamic regions located dorsal, lateral, and posterior to the POAH. This increased thermosensitivity may be due to pacemaker currents that are facilitated by cyclic nucleotides. If some of these non-POAH thermosensitive neurons promote heat loss or inhibit heat production, then their increased thermosensitivity could contribute to cGMP-induced decreases in body temperature.

Ethanol effects on temperature-sensitive hypothalamic neurons in rat brain slices

2004 ◽  
Vol 29 (7-8) ◽  
pp. 345-350 ◽  
Author(s):  
Bastian T. Wollweber ◽  
Horst Schneider ◽  
Karlheinz Voigt ◽  
Hans A. Braun
Keyword(s):  
Rat Brain ◽  
Brain Slices ◽  
Temperature Sensitive ◽  
Hypothalamic Neurons

Effects of cold adaptation and noradrenaline on thermosensitivity of rat hypothalamic neurons studiedin vitro

1995 ◽  
Vol 26 (3) ◽  
pp. 142-146 ◽  
Author(s):  
T. V. Kozyreva ◽  
F. K. Pierau
Keyword(s):  
Cold Adaptation ◽  
Hypothalamic Neurons

Carbon dioxide and pH effects on temperature-sensitive and -insensitive hypothalamic neurons

2007 ◽  
Vol 102 (4) ◽  
pp. 1357-1366 ◽  
Author(s):  
Chadwick L. Wright ◽  
Jack A. Boulant
Keyword(s):  
Heat Stroke ◽  
Ph Effects ◽  
Temperature Sensitive ◽  
Sprague Dawley ◽  
Tissue Slices ◽  
Hypothalamic Neurons ◽  
Electrophysiological Recordings ◽  
Sprague Dawley Rats ◽  
Hypothalamic Tissue ◽  
Solution Bathing

The preoptic-anterior hypothalamus (POAH) controls body temperature, and thermoregulatory responses are impaired during hypercapnia. If increased CO2 or its accompanying acidosis inhibits warm-sensitive POAH neurons, this could provide an explanation for thermoregulatory impairment during hypercapnia. To test this possibility, extracellular electrophysiological recordings determined the effects of CO2 and pH on the firing rates of both temperature-sensitive and -insensitive neurons in hypothalamic tissue slices from 89 male Sprague-Dawley rats. Firing rate activity was recorded in 121 hypothalamic neurons before, during, and after changing the CO2 concentration aerating the tissue slice chamber or changing the pH of the solution bathing the tissue slices. Increasing the aeration CO2 concentration from 5% (control) to 10% (hypercapnic) had no effect on most (i.e., 69%) POAH temperature-insensitive neurons; however, this hypercapnia inhibited the majority (i.e., 59%) of warm-sensitive neurons. CO2 affected similar proportions of (non-POAH) neurons in other hypothalamic regions. These CO2 effects appear to be due to changes in pH since the CO2-affected neurons responded similarly to isocapnic acidosis (i.e., normal CO2 and decreased pH) but were not responsive to isohydric hypercapnia (i.e., increased CO2 and normal pH). These findings may offer a neural explanation for some heat-related illnesses (e.g., exertional heat stroke) where impaired heat loss is associated with acidosis.

Attenuated temperature-sensitive respiratory syncytial virus mutants generated by cold adaptation

1994 ◽  
Vol 33 (3) ◽  
pp. 241-259 ◽  
Author(s):  
V.B. Randolph ◽  
M. Kandis ◽  
P. Stemler-Higgins ◽  
M.S. Kennelly ◽  
Y.M. McMullen ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Cold Adaptation ◽  
Temperature Sensitive ◽  
Syncytial Virus

scholarly journals Identification of Mutations Contributing to the Temperature-Sensitive, Cold-Adapted, and Attenuation Phenotypes of the Live-Attenuated Cold-Passage 45 (cp45) Human Parainfluenza Virus 3 Candidate Vaccine

1999 ◽  
Vol 73 (2) ◽  
pp. 1374-1381 ◽  
Author(s):  
Mario H. Skiadopoulos ◽  
Sonja Surman ◽  
Joanne M. Tatem ◽  
Maribel Paschalis ◽  
Shin-Lu Wu ◽  
...  
Keyword(s):  
Cold Adaptation ◽  
Vaccine Candidate ◽  
Candidate Vaccine ◽  
Parainfluenza Virus ◽  
N Gene ◽  
Temperature Sensitive ◽  
Recombinant Viruses ◽  
L Protein ◽  
Human Parainfluenza Virus ◽  
Promising Vaccine Candidate

ABSTRACT The live-attenuated human parainfluenza virus 3 (PIV3) cold-passage 45 (cp45) candidate vaccine was shown previously to be safe, immunogenic, and phenotypically stable in seronegative human infants. Previous findings indicated that each of the three amino acid substitutions in the L polymerase protein of cp45 independently confers the temperature-sensitive (ts) and attenuation (att) phenotypes but not the cold-adaptation (ca) phenotype (29).cp45 contains 12 additional potentially important point mutations in other proteins (N, C, M, F, and hemagglutinin-neuraminidase [HN]) or in cis-acting sequences (the leader region and the transcription gene start [GS] signal of the N gene), and their contribution to these phenotypes was undefined. To further characterize the genetic basis for thets, ca, and att phenotypes of this promising vaccine candidate, we constructed, using a reverse genetics system, a recombinant cp45 virus that contained all 15 cp45-specific mutations mentioned above, and found that it was essentially indistinguishable from the biologically derived cp45 on the basis of plaque size, level of temperature sensitivity, cold adaptation, level of replication in the upper and lower respiratory tract of hamsters, and ability to protect hamsters from subsequent wild-type PIV3 challenge. We then constructed recombinant viruses containing the cp45 mutations in individual proteins as well as several combinations of mutations. Analysis of these recombinant viruses revealed that multiple cp45 mutations distributed throughout the genome contribute to the ts, ca, andatt phenotypes. In addition to the mutations in the L gene, at least one other mutation in the 3′ N region (i.e., including the leader, N GS, and N coding changes) contributes to thets phenotype. A recombinant virus containing all thecp45 mutations except those in L was more tsthan cp45, illustrating the complex nature of this phenotype. The ca phenotype of cp45 also is a complex composite phenotype, reflecting contributions of at least three separate genetic elements, namely, mutations within the 3′ N region, the L protein, and the C-M-F-HN region. The att phenotype is a composite of both ts and non-ts mutations. Attenuating ts mutations are located in the L protein, and non-ts attenuating mutations are located in the C and F proteins. The presence of multiple ts and non-ts attenuating mutations in cp45 likely contributes to the high level of attenuation and phenotypic stability of this promising vaccine candidate.

Oncogenesis and the Lucké Virus

1968 ◽  
Vol 26 ◽  
pp. 200-201
Author(s):  
A. E. Vatter ◽  
J. Zambernard
Keyword(s):  
Rna Viruses ◽  
Vegetative State ◽  
Temperature Sensitive ◽  
Structural Level ◽  
Oncogenic Viruses ◽  
Dna Viruses ◽  
Leopard Frogs ◽  
Renal Adenocarcinoma ◽  
Induced Tumors ◽  
Northern Leopard Frogs

Oncogenic viruses, like viruses in general, can be divided into two classes, those that contain deoxyribonucleic acid (DNA) and those that contain ribonucleic acid (RNA). The RNA viruses have been recovered readily from the tumors which they cause whereas, the DNA-virus induced tumors have not yielded the virus. Since DNA viruses cannot be recovered, the bulk of present day investigations have been concerned with RNA viruses.The Lucké renal adenocarcinoma is a spontaneous tumor which occurs in northern leopard frogs (Rana pipiens) and has received increased attention in recent years because of its probable viral etiology. This hypothesis was first advanced by Lucké after he observed intranuclear inclusions in some of the tumor cells. Tumors with inclusions were examined at the fine structural level by Fawcett who showed that they contained immature and mature virus˗like particles.The use of this system in the study of oncogenic tumors offers several unique features, the virus has been shown to contain DNA and it can be recovered from the tumor, also, it is temperature sensitive. This latter feature is of importance because the virus can be transformed from a latent to a vegetative state by lowering or elevating the environmental temperature.

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