Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SHIVERING”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1985

Myelin deficient (shimld) mutant allele: morphological comparison with shiverer (shi) allele on a B6C3 mouse stock.

A new B6C3 stock of shimld mutant mice is compared in terms of behavior and CNS morphology with both a B6C3 shi stock and reports on other shimld animals. Defects of B6C3 shimld myelination seen at postnatal day 21 (P-21) are comparable to those in B6C3 shi with respect to % axons myelinated, sheath thickness, errors in the wrapping and targeting of myelin and abnormal oligodendrocyte shape. The two mutations are similarly expressed in cerebellar organotypic cultures. However, the major dense line (MDL) is present in a few shimld myelin sheaths at P-21 and a few sheaths show myelin basic protein by immunocytochemistry, while neither phenomenon is seen in shi at this age in the same CNS regions. Shimld mice survive their disease significantly better than shi. The shimld stock currently under study elsewhere differs from this B6C3 stock in that MDL was reported only in older animals, and behavior and survival were severely compromised.

Alleles↗
PubMed1987

Hyperthermia induced by pre-pontine knife-cut: evidence for a tonic inhibition of non-shivering thermogenesis in anaesthetized rat.

Temperature of colon, interscapular brown adipose tissue (IBAT) and paw skin (index of vasomotor activity) were monitored before and after microwire knife lesions at the pre-pontine or/and the post-mammillary levels in the urethane-anaesthetized rats at room temperature of 23-24 degrees C. Following the pre-pontine, but not the post-mammillary cut, colonic and IBAT temperatures increased by 3-4 degrees C within 90-240 min. IBAT temperature rose faster with a shorter latency and attained a higher steady-state value than colonic temperature; skin temperature, however rose by only 0.8 degrees C. A procaine microinjection into the pre-pontine area transiently increased by more than 1 degree C both colonic and IBAT temperatures, with similar kinetics as for the knife cut. Cardiac output distribution was measured using radiolabelled microspheres. Brown adipose tissue (BAT) was found to be the only organ to which the fractional blood flow increased dramatically (12 times over baseline value) during the development of hyperthermia. Propanolol, injected after the hyperthermia had fully developed, decreased IBAT and then colonic temperatures. Hexamethonium decreased both colonic and IBAT temperatures with a concomitant rise in skin temperature while tubocurarine was without effect. It is concluded that the hyperthermia observed after the pre-pontine lesion results from an increased sympathetic stimulation of BAT thermogenesis triggered by the release of a tonic inhibitory control on its heat production. Such an inhibitory system would be located somewhere between the lower midbrain and the upper pons.

Adipose Tissue, Brown↗
PubMed1988

Shiverer jimpy double mutant mice. IV. Five combinations of allelic mutations produce three morphological phenotypes.

Mice which simultaneously express mutant genes at both the shi and jp loci (double mutant mice) have phenotypes much more complex than simple addition of individual mutant characteristics. Morphological study of shi jpmsd, shimld jp, and shi/shimld jp, and comparison with previously studied shi jp and shimld jpmsd, shows that 3 classes of central nervous system (CNS) white matter morphology are produced. (1) shi jp shows suppression of most jp characteristics: it is like shi except for more major dense line, and possibly more myelin, than shi alone. No other combination has as much myelin or any major dense line at all. (2) shi jpmsd has qualitative and quantitative characteristics intermediate between the two single mutants. (3) All combinations studied involving shimld have much less myelin than either single mutant. Qualitatively they express most jp locus features but suppress all shi locus features except abnormalities of myelin compaction. The difference between shi and shimld has more influence on the double mutant morphology than the difference between jp and jpmsd. In the 3-mutant combination, shi/shimld jp, the influence of shimld completely overrides that of shi. These morphological phenotypes resist assignment to any hierarchy of normalcy, and their specific features have no simple explanation in presently known molecular biology of the shi and jp locus mutations. They suggest the possibility of multiple copies and multiple primary functions of the messages at these loci.

Animals↗
PubMed1990

Inhibition by vasodilators of noradrenaline and vasoconstrictor-mediated, but not skeletal muscle contraction-induced oxygen uptake in the perfused rat hindlimb; implications for non-shivering thermogenesis in muscle tissue.

1. The effect of noradrenaline as well as of vasopressin and angiotensin II to increase oxygen uptake and perfusion pressure by the isolated perfused rat hindlimb were completely inhibited by the vasodilators, nitroprusside (0.5 mM), nifedipine (2.5 microM) and isoprenaline (50 nM). 2. Oxygen uptake due to sciatic nerve stimulation of skeletal muscle contraction was not inhibited by 0.5 mM nitroprusside but was found to increase further that produced by a maximum dose of either noradrenaline or angiotensin II. 3. Analysis of high energy phosphates in samples of freeze-clamped hindlimb muscle showed no difference before and after vasoconstrictor addition or with muscle sampled in vivo. 4. It is concluded that norepinephrine mediated increase in oxygen uptake by the perfused rat hindlimb results from its vasoconstrictor action.

Adenosine Diphosphate↗
PubMed2002

Chemical stimulation of the dorsomedial hypothalamus evokes non-shivering thermogenesis in anesthetized rats.

Disinhibition of neurons in the dorsomedial hypothalamus (DMH) by microinjection of the GABA(A) receptor antagonist bicuculline methiodide (BMI) elicits a range of autonomic and endocrine changes resembling those seen in experimental paradigms for emotional stress. Stress in rats is also known to provoke increases in body temperature resulting in part from sympathetically mediated activation of brown fat. The purpose of the present study was to examine the effect of microinjection of BMI into the DMH on core body temperature and temperature of brown fat in rats. In anesthetized preparations, microinjection of BMI 10 pmol/50 nl into the DMH and adjoining posterior hypothalamus elicited marked and rapid increases in temperature in interscapular brown adipose tissue (IBAT) and lesser delayed elevations in rectal temperature. Similar injections into the paraventricular nucleus or ventromedial hypothalamus had no effect on either parameter. Peak increases in IBAT were significantly correlated with both peak increases in core temperature and maximal increases in heart rate that accompanied these changes, and all of these effects were abolished by systemic treatment with propranolol 1 mg/kg. In conscious rats instrumented for telemetry, microinjection of BMI 10 pmol/100 nl into the DMH evoked marked increases in core temperature as well as heart rate, locomotor activity, and plasma ACTH. The increase in core temperature occurred with a delayed time course similar to that seen in anesthetized preparations. These results indicate that activation of neurons in the DMH provokes increases in body temperature resulting in large part from sympathoadrenally-mediated activation of brown fat.

Adipose Tissue, Brown↗
PubMed1997

Potential for non-shivering thermogenesis in perfused chicken (Gallus domesticus) muscle.

The humoral modulation of resting muscle heat production of chickens (Gallus domesticus) was investigated in vitro. The resting distal lower limb was perfused via the popliteal artery at 25 degrees C without erythrocytes at constant flow. The preparation was stable for at least 3 hr, showing a constant oxygen uptake (MO2) and perfusion pressure as well as adequately maintaining muscle energy charge and creatine phosphate: creatine ratio. Noradrenaline (NOR), adrenaline (ADR) and serotonin (5-HT) each caused a dose-dependent rise in perfusion pressure. NOR and ADR evoked increased MO2 at low doses eventually followed by decreased MO2 at higher agonist concentrations. 5-HT gave smaller but qualitatively similar MO2 effects. The actions of 50 nM NOR were blocked by prazosin (10 microM) and nitroprusside (0.5 mM), but not altered by propranolol (10 microM). NOR-induced stimulatory MO2 changes in the presence of pharmacological concentrations (1 microM) of glucagon were more pronounced and the thermogenic concentration range of NOR was increased. Taken together, these in vitro findings demonstrate a potential for vasoconstrictor-controlled muscle nonshivering thermogenesis in birds as in marsupials and mammals, suggesting that vascular control of muscle MO2 may be a widespread biological mechanism. The possible implications of these findings for avian nonshivering thermogenesis are discussed.

Animals↗
PubMed1990

Rapid preimplantation detection of mutant (shiverer) and normal alleles of the mouse myelin basic protein gene allowing selective implantation and birth of live young.

As a model for the detection of human genetic disease in preimplantation embryos, we describe a method in which trophectoderm biopsy samples from viable mouse blastocysts are simultaneously analyzed for the presence of a normal or mutant allele of the myelin basic protein gene by the polymerase chain reaction. The biopsied embryos are kept in culture during analysis of biopsied material and later reintroduced to a foster mother. Prenatal diagnosis can be completed in less than 7 hr. The identity of either amplification product was proved conclusively by direct sequence analysis of amplified products. Ninety-six percent of recovered blastocysts survived biopsy, as judged by re-formation of a blastocyst cavity in culture. Fifty-nine percent of the biopsied embryos established pregnancy by day 6.5, compared to 88% of unmanipulated controls. This approach can be applied to preimplantation diagnosis of human genetic diseases by using extraembryonic cells from blastocysts obtained after in vitro fertilization or uterine lavage. It will make possible the elimination of a mutant allele from a family in a single generation.

Alleles↗
PubMed1979

Effect of dietary composition and cold exposure on non-shivering thermogenesis in young pigs and its alteration by the beta-blocker propranolol.

1. Young pigs were fed on three diets consecutively, each diet being given for 1 week. The diets were given in random order as (g pig feed/kg body-weight): (a) 20, (b) 60, (c) 20 plus a supplement with the energy equivalent of 40 g pig feed/kg. The supplements included desiccated coconut, fish meal and glucose. 2. At the end of each week resting metabolic rate, beginning 12--14 h after feeding, was measured overnight using an open-circuit respiration chamber at thermoneutrality. 3. The oxygen consumption of pigs on the 60 g/kg diet was always higher than on the 20 g/kg diet. The addition of desiccated coconut, or fish meal also increased metabolic rate; whereas with added glucose, O2 consumption tended to be even lower than on 20 g/kg alone. 4. The administration of the beta-blocker propranolol to pigs on ad lib, food intake reduced the rate of overnight resting O2 consumption, measured from 10 until 20 h after feeding, by 12%, but it had no effect on O2 consumption when the intake was 20 g feed/kg. Exposure to mild cold (15 degrees) caused an increase in O2 consumption and this was reduced by 14% after injection of propranolol.

Animals↗